![Andrea Arcangeli](/assets/img/avatar_default.png)
This will provide fully accuracy to the mapcount calculation in the
write protect faults, so page pinning will not get broken by false
positive copy-on-writes.
total_mapcount() isn't the right calculation needed in
reuse_swap_page(), so this introduces a page_trans_huge_mapcount()
that is effectively the full accurate return value for page_mapcount()
if dealing with Transparent Hugepages, however we only use the
page_trans_huge_mapcount() during COW faults where it strictly needed,
due to its higher runtime cost.
This also provide at practical zero cost the total_mapcount
information which is needed to know if we can still relocate the page
anon_vma to the local vma. If page_trans_huge_mapcount() returns 1 we
can reuse the page no matter if it's a pte or a pmd_trans_huge
triggering the fault, but we can only relocate the page anon_vma to
the local vma->anon_vma if we're sure it's only this "vma" mapping the
whole THP physical range.
Kirill A. Shutemov discovered the problem with moving the page
anon_vma to the local vma->anon_vma in a previous version of this
patch and another problem in the way page_move_anon_rmap() was called.
Andrew Morton discovered that CONFIG_SWAP=n wouldn't build in a
previous version, because reuse_swap_page must be a macro to call
page_trans_huge_mapcount from swap.h, so this uses a macro again
instead of an inline function. With this change at least it's a less
dangerous usage than it was before, because "page" is used only once
now, while with the previous code reuse_swap_page(page++) would have
called page_mapcount on page+1 and it would have increased page twice
instead of just once.
Dean Luick noticed an uninitialized variable that could result in a
rmap inefficiency for the non-THP case in a previous version.
Mike Marciniszyn said:
: Our RDMA tests are seeing an issue with memory locking that bisects to
: commit 61f5d698cc
("mm: re-enable THP")
:
: The test program registers two rather large MRs (512M) and RDMA
: writes data to a passive peer using the first and RDMA reads it back
: into the second MR and compares that data. The sizes are chosen randomly
: between 0 and 1024 bytes.
:
: The test will get through a few (<= 4 iterations) and then gets a
: compare error.
:
: Tracing indicates the kernel logical addresses associated with the individual
: pages at registration ARE correct , the data in the "RDMA read response only"
: packets ARE correct.
:
: The "corruption" occurs when the packet crosse two pages that are not physically
: contiguous. The second page reads back as zero in the program.
:
: It looks like the user VA at the point of the compare error no longer points to
: the same physical address as was registered.
:
: This patch totally resolves the issue!
Link: http://lkml.kernel.org/r/1462547040-1737-2-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Reviewed-by: Dean Luick <dean.luick@intel.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Tested-by: Josh Collier <josh.d.collier@intel.com>
Cc: Marc Haber <mh+linux-kernel@zugschlus.de>
Cc: <stable@vger.kernel.org> [4.5]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
3527 lines
92 KiB
C
3527 lines
92 KiB
C
/*
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* Copyright (C) 2009 Red Hat, Inc.
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/highmem.h>
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#include <linux/hugetlb.h>
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#include <linux/mmu_notifier.h>
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#include <linux/rmap.h>
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#include <linux/swap.h>
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#include <linux/shrinker.h>
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#include <linux/mm_inline.h>
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#include <linux/swapops.h>
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#include <linux/dax.h>
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#include <linux/kthread.h>
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#include <linux/khugepaged.h>
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#include <linux/freezer.h>
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#include <linux/pfn_t.h>
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#include <linux/mman.h>
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#include <linux/memremap.h>
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#include <linux/pagemap.h>
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#include <linux/debugfs.h>
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#include <linux/migrate.h>
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#include <linux/hashtable.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/page_idle.h>
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#include <asm/tlb.h>
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#include <asm/pgalloc.h>
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#include "internal.h"
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enum scan_result {
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SCAN_FAIL,
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SCAN_SUCCEED,
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SCAN_PMD_NULL,
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SCAN_EXCEED_NONE_PTE,
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SCAN_PTE_NON_PRESENT,
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SCAN_PAGE_RO,
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SCAN_NO_REFERENCED_PAGE,
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SCAN_PAGE_NULL,
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SCAN_SCAN_ABORT,
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SCAN_PAGE_COUNT,
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SCAN_PAGE_LRU,
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SCAN_PAGE_LOCK,
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SCAN_PAGE_ANON,
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SCAN_PAGE_COMPOUND,
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SCAN_ANY_PROCESS,
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SCAN_VMA_NULL,
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SCAN_VMA_CHECK,
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SCAN_ADDRESS_RANGE,
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SCAN_SWAP_CACHE_PAGE,
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SCAN_DEL_PAGE_LRU,
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SCAN_ALLOC_HUGE_PAGE_FAIL,
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SCAN_CGROUP_CHARGE_FAIL
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};
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#define CREATE_TRACE_POINTS
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#include <trace/events/huge_memory.h>
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/*
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* By default transparent hugepage support is disabled in order that avoid
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* to risk increase the memory footprint of applications without a guaranteed
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* benefit. When transparent hugepage support is enabled, is for all mappings,
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* and khugepaged scans all mappings.
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* Defrag is invoked by khugepaged hugepage allocations and by page faults
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* for all hugepage allocations.
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*/
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unsigned long transparent_hugepage_flags __read_mostly =
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
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(1<<TRANSPARENT_HUGEPAGE_FLAG)|
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#endif
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
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(1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
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#endif
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(1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
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(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
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(1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
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/* default scan 8*512 pte (or vmas) every 30 second */
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static unsigned int khugepaged_pages_to_scan __read_mostly;
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static unsigned int khugepaged_pages_collapsed;
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static unsigned int khugepaged_full_scans;
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static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
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/* during fragmentation poll the hugepage allocator once every minute */
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static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
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static struct task_struct *khugepaged_thread __read_mostly;
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static DEFINE_MUTEX(khugepaged_mutex);
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static DEFINE_SPINLOCK(khugepaged_mm_lock);
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static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
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/*
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* default collapse hugepages if there is at least one pte mapped like
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* it would have happened if the vma was large enough during page
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* fault.
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*/
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static unsigned int khugepaged_max_ptes_none __read_mostly;
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static int khugepaged(void *none);
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static int khugepaged_slab_init(void);
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static void khugepaged_slab_exit(void);
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#define MM_SLOTS_HASH_BITS 10
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static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
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static struct kmem_cache *mm_slot_cache __read_mostly;
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/**
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* struct mm_slot - hash lookup from mm to mm_slot
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* @hash: hash collision list
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* @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
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* @mm: the mm that this information is valid for
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*/
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struct mm_slot {
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struct hlist_node hash;
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struct list_head mm_node;
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struct mm_struct *mm;
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};
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/**
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* struct khugepaged_scan - cursor for scanning
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* @mm_head: the head of the mm list to scan
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* @mm_slot: the current mm_slot we are scanning
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* @address: the next address inside that to be scanned
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*
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* There is only the one khugepaged_scan instance of this cursor structure.
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*/
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struct khugepaged_scan {
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struct list_head mm_head;
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struct mm_slot *mm_slot;
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unsigned long address;
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};
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static struct khugepaged_scan khugepaged_scan = {
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.mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
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};
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static struct shrinker deferred_split_shrinker;
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static void set_recommended_min_free_kbytes(void)
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{
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struct zone *zone;
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int nr_zones = 0;
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unsigned long recommended_min;
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for_each_populated_zone(zone)
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nr_zones++;
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/* Ensure 2 pageblocks are free to assist fragmentation avoidance */
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recommended_min = pageblock_nr_pages * nr_zones * 2;
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/*
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* Make sure that on average at least two pageblocks are almost free
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* of another type, one for a migratetype to fall back to and a
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* second to avoid subsequent fallbacks of other types There are 3
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* MIGRATE_TYPES we care about.
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*/
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recommended_min += pageblock_nr_pages * nr_zones *
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MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
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/* don't ever allow to reserve more than 5% of the lowmem */
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recommended_min = min(recommended_min,
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(unsigned long) nr_free_buffer_pages() / 20);
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recommended_min <<= (PAGE_SHIFT-10);
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if (recommended_min > min_free_kbytes) {
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if (user_min_free_kbytes >= 0)
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pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n",
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min_free_kbytes, recommended_min);
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min_free_kbytes = recommended_min;
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}
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setup_per_zone_wmarks();
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}
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static int start_stop_khugepaged(void)
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{
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int err = 0;
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if (khugepaged_enabled()) {
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if (!khugepaged_thread)
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khugepaged_thread = kthread_run(khugepaged, NULL,
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"khugepaged");
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if (IS_ERR(khugepaged_thread)) {
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pr_err("khugepaged: kthread_run(khugepaged) failed\n");
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err = PTR_ERR(khugepaged_thread);
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khugepaged_thread = NULL;
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goto fail;
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}
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if (!list_empty(&khugepaged_scan.mm_head))
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wake_up_interruptible(&khugepaged_wait);
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set_recommended_min_free_kbytes();
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} else if (khugepaged_thread) {
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kthread_stop(khugepaged_thread);
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khugepaged_thread = NULL;
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}
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fail:
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return err;
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}
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static atomic_t huge_zero_refcount;
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struct page *huge_zero_page __read_mostly;
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struct page *get_huge_zero_page(void)
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{
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struct page *zero_page;
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retry:
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if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
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return READ_ONCE(huge_zero_page);
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zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
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HPAGE_PMD_ORDER);
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if (!zero_page) {
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count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
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return NULL;
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}
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count_vm_event(THP_ZERO_PAGE_ALLOC);
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preempt_disable();
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if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
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preempt_enable();
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__free_pages(zero_page, compound_order(zero_page));
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goto retry;
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}
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/* We take additional reference here. It will be put back by shrinker */
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atomic_set(&huge_zero_refcount, 2);
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preempt_enable();
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return READ_ONCE(huge_zero_page);
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}
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void put_huge_zero_page(void)
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{
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/*
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* Counter should never go to zero here. Only shrinker can put
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* last reference.
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*/
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BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
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}
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static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
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struct shrink_control *sc)
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{
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/* we can free zero page only if last reference remains */
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return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
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}
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static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
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struct shrink_control *sc)
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{
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if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
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struct page *zero_page = xchg(&huge_zero_page, NULL);
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BUG_ON(zero_page == NULL);
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__free_pages(zero_page, compound_order(zero_page));
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return HPAGE_PMD_NR;
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}
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return 0;
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}
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static struct shrinker huge_zero_page_shrinker = {
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.count_objects = shrink_huge_zero_page_count,
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.scan_objects = shrink_huge_zero_page_scan,
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.seeks = DEFAULT_SEEKS,
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};
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#ifdef CONFIG_SYSFS
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static ssize_t triple_flag_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count,
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enum transparent_hugepage_flag enabled,
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enum transparent_hugepage_flag deferred,
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enum transparent_hugepage_flag req_madv)
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{
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if (!memcmp("defer", buf,
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min(sizeof("defer")-1, count))) {
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if (enabled == deferred)
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return -EINVAL;
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clear_bit(enabled, &transparent_hugepage_flags);
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clear_bit(req_madv, &transparent_hugepage_flags);
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set_bit(deferred, &transparent_hugepage_flags);
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} else if (!memcmp("always", buf,
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min(sizeof("always")-1, count))) {
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clear_bit(deferred, &transparent_hugepage_flags);
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clear_bit(req_madv, &transparent_hugepage_flags);
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set_bit(enabled, &transparent_hugepage_flags);
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} else if (!memcmp("madvise", buf,
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min(sizeof("madvise")-1, count))) {
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clear_bit(enabled, &transparent_hugepage_flags);
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clear_bit(deferred, &transparent_hugepage_flags);
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set_bit(req_madv, &transparent_hugepage_flags);
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} else if (!memcmp("never", buf,
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min(sizeof("never")-1, count))) {
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clear_bit(enabled, &transparent_hugepage_flags);
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clear_bit(req_madv, &transparent_hugepage_flags);
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clear_bit(deferred, &transparent_hugepage_flags);
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} else
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return -EINVAL;
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return count;
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}
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static ssize_t enabled_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
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return sprintf(buf, "[always] madvise never\n");
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else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
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return sprintf(buf, "always [madvise] never\n");
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else
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return sprintf(buf, "always madvise [never]\n");
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}
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static ssize_t enabled_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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ssize_t ret;
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ret = triple_flag_store(kobj, attr, buf, count,
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TRANSPARENT_HUGEPAGE_FLAG,
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TRANSPARENT_HUGEPAGE_FLAG,
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TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
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|
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if (ret > 0) {
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int err;
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|
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mutex_lock(&khugepaged_mutex);
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err = start_stop_khugepaged();
|
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mutex_unlock(&khugepaged_mutex);
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|
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if (err)
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ret = err;
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}
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return ret;
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}
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static struct kobj_attribute enabled_attr =
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__ATTR(enabled, 0644, enabled_show, enabled_store);
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|
|
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static ssize_t single_flag_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf,
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enum transparent_hugepage_flag flag)
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{
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return sprintf(buf, "%d\n",
|
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!!test_bit(flag, &transparent_hugepage_flags));
|
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}
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|
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static ssize_t single_flag_store(struct kobject *kobj,
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struct kobj_attribute *attr,
|
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const char *buf, size_t count,
|
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enum transparent_hugepage_flag flag)
|
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{
|
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unsigned long value;
|
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int ret;
|
|
|
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ret = kstrtoul(buf, 10, &value);
|
|
if (ret < 0)
|
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return ret;
|
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if (value > 1)
|
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return -EINVAL;
|
|
|
|
if (value)
|
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set_bit(flag, &transparent_hugepage_flags);
|
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else
|
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clear_bit(flag, &transparent_hugepage_flags);
|
|
|
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return count;
|
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}
|
|
|
|
/*
|
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* Currently defrag only disables __GFP_NOWAIT for allocation. A blind
|
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* __GFP_REPEAT is too aggressive, it's never worth swapping tons of
|
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* memory just to allocate one more hugepage.
|
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*/
|
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static ssize_t defrag_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
|
|
{
|
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if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
|
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return sprintf(buf, "[always] defer madvise never\n");
|
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if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
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return sprintf(buf, "always [defer] madvise never\n");
|
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else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
|
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return sprintf(buf, "always defer [madvise] never\n");
|
|
else
|
|
return sprintf(buf, "always defer madvise [never]\n");
|
|
|
|
}
|
|
static ssize_t defrag_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
return triple_flag_store(kobj, attr, buf, count,
|
|
TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
|
|
TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
|
|
TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
|
|
}
|
|
static struct kobj_attribute defrag_attr =
|
|
__ATTR(defrag, 0644, defrag_show, defrag_store);
|
|
|
|
static ssize_t use_zero_page_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr, char *buf)
|
|
{
|
|
return single_flag_show(kobj, attr, buf,
|
|
TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
|
|
}
|
|
static ssize_t use_zero_page_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr, const char *buf, size_t count)
|
|
{
|
|
return single_flag_store(kobj, attr, buf, count,
|
|
TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
|
|
}
|
|
static struct kobj_attribute use_zero_page_attr =
|
|
__ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
|
|
#ifdef CONFIG_DEBUG_VM
|
|
static ssize_t debug_cow_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr, char *buf)
|
|
{
|
|
return single_flag_show(kobj, attr, buf,
|
|
TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
|
|
}
|
|
static ssize_t debug_cow_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
return single_flag_store(kobj, attr, buf, count,
|
|
TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
|
|
}
|
|
static struct kobj_attribute debug_cow_attr =
|
|
__ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
|
|
#endif /* CONFIG_DEBUG_VM */
|
|
|
|
static struct attribute *hugepage_attr[] = {
|
|
&enabled_attr.attr,
|
|
&defrag_attr.attr,
|
|
&use_zero_page_attr.attr,
|
|
#ifdef CONFIG_DEBUG_VM
|
|
&debug_cow_attr.attr,
|
|
#endif
|
|
NULL,
|
|
};
|
|
|
|
static struct attribute_group hugepage_attr_group = {
|
|
.attrs = hugepage_attr,
|
|
};
|
|
|
|
static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
char *buf)
|
|
{
|
|
return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
|
|
}
|
|
|
|
static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
unsigned long msecs;
|
|
int err;
|
|
|
|
err = kstrtoul(buf, 10, &msecs);
|
|
if (err || msecs > UINT_MAX)
|
|
return -EINVAL;
|
|
|
|
khugepaged_scan_sleep_millisecs = msecs;
|
|
wake_up_interruptible(&khugepaged_wait);
|
|
|
|
return count;
|
|
}
|
|
static struct kobj_attribute scan_sleep_millisecs_attr =
|
|
__ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
|
|
scan_sleep_millisecs_store);
|
|
|
|
static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
char *buf)
|
|
{
|
|
return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
|
|
}
|
|
|
|
static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
unsigned long msecs;
|
|
int err;
|
|
|
|
err = kstrtoul(buf, 10, &msecs);
|
|
if (err || msecs > UINT_MAX)
|
|
return -EINVAL;
|
|
|
|
khugepaged_alloc_sleep_millisecs = msecs;
|
|
wake_up_interruptible(&khugepaged_wait);
|
|
|
|
return count;
|
|
}
|
|
static struct kobj_attribute alloc_sleep_millisecs_attr =
|
|
__ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
|
|
alloc_sleep_millisecs_store);
|
|
|
|
static ssize_t pages_to_scan_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
char *buf)
|
|
{
|
|
return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
|
|
}
|
|
static ssize_t pages_to_scan_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
int err;
|
|
unsigned long pages;
|
|
|
|
err = kstrtoul(buf, 10, &pages);
|
|
if (err || !pages || pages > UINT_MAX)
|
|
return -EINVAL;
|
|
|
|
khugepaged_pages_to_scan = pages;
|
|
|
|
return count;
|
|
}
|
|
static struct kobj_attribute pages_to_scan_attr =
|
|
__ATTR(pages_to_scan, 0644, pages_to_scan_show,
|
|
pages_to_scan_store);
|
|
|
|
static ssize_t pages_collapsed_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
char *buf)
|
|
{
|
|
return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
|
|
}
|
|
static struct kobj_attribute pages_collapsed_attr =
|
|
__ATTR_RO(pages_collapsed);
|
|
|
|
static ssize_t full_scans_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
char *buf)
|
|
{
|
|
return sprintf(buf, "%u\n", khugepaged_full_scans);
|
|
}
|
|
static struct kobj_attribute full_scans_attr =
|
|
__ATTR_RO(full_scans);
|
|
|
|
static ssize_t khugepaged_defrag_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr, char *buf)
|
|
{
|
|
return single_flag_show(kobj, attr, buf,
|
|
TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
|
|
}
|
|
static ssize_t khugepaged_defrag_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
return single_flag_store(kobj, attr, buf, count,
|
|
TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
|
|
}
|
|
static struct kobj_attribute khugepaged_defrag_attr =
|
|
__ATTR(defrag, 0644, khugepaged_defrag_show,
|
|
khugepaged_defrag_store);
|
|
|
|
/*
|
|
* max_ptes_none controls if khugepaged should collapse hugepages over
|
|
* any unmapped ptes in turn potentially increasing the memory
|
|
* footprint of the vmas. When max_ptes_none is 0 khugepaged will not
|
|
* reduce the available free memory in the system as it
|
|
* runs. Increasing max_ptes_none will instead potentially reduce the
|
|
* free memory in the system during the khugepaged scan.
|
|
*/
|
|
static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
char *buf)
|
|
{
|
|
return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
|
|
}
|
|
static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
int err;
|
|
unsigned long max_ptes_none;
|
|
|
|
err = kstrtoul(buf, 10, &max_ptes_none);
|
|
if (err || max_ptes_none > HPAGE_PMD_NR-1)
|
|
return -EINVAL;
|
|
|
|
khugepaged_max_ptes_none = max_ptes_none;
|
|
|
|
return count;
|
|
}
|
|
static struct kobj_attribute khugepaged_max_ptes_none_attr =
|
|
__ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
|
|
khugepaged_max_ptes_none_store);
|
|
|
|
static struct attribute *khugepaged_attr[] = {
|
|
&khugepaged_defrag_attr.attr,
|
|
&khugepaged_max_ptes_none_attr.attr,
|
|
&pages_to_scan_attr.attr,
|
|
&pages_collapsed_attr.attr,
|
|
&full_scans_attr.attr,
|
|
&scan_sleep_millisecs_attr.attr,
|
|
&alloc_sleep_millisecs_attr.attr,
|
|
NULL,
|
|
};
|
|
|
|
static struct attribute_group khugepaged_attr_group = {
|
|
.attrs = khugepaged_attr,
|
|
.name = "khugepaged",
|
|
};
|
|
|
|
static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
|
|
{
|
|
int err;
|
|
|
|
*hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
|
|
if (unlikely(!*hugepage_kobj)) {
|
|
pr_err("failed to create transparent hugepage kobject\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
|
|
if (err) {
|
|
pr_err("failed to register transparent hugepage group\n");
|
|
goto delete_obj;
|
|
}
|
|
|
|
err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
|
|
if (err) {
|
|
pr_err("failed to register transparent hugepage group\n");
|
|
goto remove_hp_group;
|
|
}
|
|
|
|
return 0;
|
|
|
|
remove_hp_group:
|
|
sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
|
|
delete_obj:
|
|
kobject_put(*hugepage_kobj);
|
|
return err;
|
|
}
|
|
|
|
static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
|
|
{
|
|
sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
|
|
sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
|
|
kobject_put(hugepage_kobj);
|
|
}
|
|
#else
|
|
static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
|
|
{
|
|
}
|
|
#endif /* CONFIG_SYSFS */
|
|
|
|
static int __init hugepage_init(void)
|
|
{
|
|
int err;
|
|
struct kobject *hugepage_kobj;
|
|
|
|
if (!has_transparent_hugepage()) {
|
|
transparent_hugepage_flags = 0;
|
|
return -EINVAL;
|
|
}
|
|
|
|
khugepaged_pages_to_scan = HPAGE_PMD_NR * 8;
|
|
khugepaged_max_ptes_none = HPAGE_PMD_NR - 1;
|
|
/*
|
|
* hugepages can't be allocated by the buddy allocator
|
|
*/
|
|
MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
|
|
/*
|
|
* we use page->mapping and page->index in second tail page
|
|
* as list_head: assuming THP order >= 2
|
|
*/
|
|
MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
|
|
|
|
err = hugepage_init_sysfs(&hugepage_kobj);
|
|
if (err)
|
|
goto err_sysfs;
|
|
|
|
err = khugepaged_slab_init();
|
|
if (err)
|
|
goto err_slab;
|
|
|
|
err = register_shrinker(&huge_zero_page_shrinker);
|
|
if (err)
|
|
goto err_hzp_shrinker;
|
|
err = register_shrinker(&deferred_split_shrinker);
|
|
if (err)
|
|
goto err_split_shrinker;
|
|
|
|
/*
|
|
* By default disable transparent hugepages on smaller systems,
|
|
* where the extra memory used could hurt more than TLB overhead
|
|
* is likely to save. The admin can still enable it through /sys.
|
|
*/
|
|
if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
|
|
transparent_hugepage_flags = 0;
|
|
return 0;
|
|
}
|
|
|
|
err = start_stop_khugepaged();
|
|
if (err)
|
|
goto err_khugepaged;
|
|
|
|
return 0;
|
|
err_khugepaged:
|
|
unregister_shrinker(&deferred_split_shrinker);
|
|
err_split_shrinker:
|
|
unregister_shrinker(&huge_zero_page_shrinker);
|
|
err_hzp_shrinker:
|
|
khugepaged_slab_exit();
|
|
err_slab:
|
|
hugepage_exit_sysfs(hugepage_kobj);
|
|
err_sysfs:
|
|
return err;
|
|
}
|
|
subsys_initcall(hugepage_init);
|
|
|
|
static int __init setup_transparent_hugepage(char *str)
|
|
{
|
|
int ret = 0;
|
|
if (!str)
|
|
goto out;
|
|
if (!strcmp(str, "always")) {
|
|
set_bit(TRANSPARENT_HUGEPAGE_FLAG,
|
|
&transparent_hugepage_flags);
|
|
clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
|
|
&transparent_hugepage_flags);
|
|
ret = 1;
|
|
} else if (!strcmp(str, "madvise")) {
|
|
clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
|
|
&transparent_hugepage_flags);
|
|
set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
|
|
&transparent_hugepage_flags);
|
|
ret = 1;
|
|
} else if (!strcmp(str, "never")) {
|
|
clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
|
|
&transparent_hugepage_flags);
|
|
clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
|
|
&transparent_hugepage_flags);
|
|
ret = 1;
|
|
}
|
|
out:
|
|
if (!ret)
|
|
pr_warn("transparent_hugepage= cannot parse, ignored\n");
|
|
return ret;
|
|
}
|
|
__setup("transparent_hugepage=", setup_transparent_hugepage);
|
|
|
|
pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
|
|
{
|
|
if (likely(vma->vm_flags & VM_WRITE))
|
|
pmd = pmd_mkwrite(pmd);
|
|
return pmd;
|
|
}
|
|
|
|
static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
|
|
{
|
|
pmd_t entry;
|
|
entry = mk_pmd(page, prot);
|
|
entry = pmd_mkhuge(entry);
|
|
return entry;
|
|
}
|
|
|
|
static inline struct list_head *page_deferred_list(struct page *page)
|
|
{
|
|
/*
|
|
* ->lru in the tail pages is occupied by compound_head.
|
|
* Let's use ->mapping + ->index in the second tail page as list_head.
|
|
*/
|
|
return (struct list_head *)&page[2].mapping;
|
|
}
|
|
|
|
void prep_transhuge_page(struct page *page)
|
|
{
|
|
/*
|
|
* we use page->mapping and page->indexlru in second tail page
|
|
* as list_head: assuming THP order >= 2
|
|
*/
|
|
|
|
INIT_LIST_HEAD(page_deferred_list(page));
|
|
set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
|
|
}
|
|
|
|
static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
|
|
struct vm_area_struct *vma,
|
|
unsigned long address, pmd_t *pmd,
|
|
struct page *page, gfp_t gfp,
|
|
unsigned int flags)
|
|
{
|
|
struct mem_cgroup *memcg;
|
|
pgtable_t pgtable;
|
|
spinlock_t *ptl;
|
|
unsigned long haddr = address & HPAGE_PMD_MASK;
|
|
|
|
VM_BUG_ON_PAGE(!PageCompound(page), page);
|
|
|
|
if (mem_cgroup_try_charge(page, mm, gfp, &memcg, true)) {
|
|
put_page(page);
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
pgtable = pte_alloc_one(mm, haddr);
|
|
if (unlikely(!pgtable)) {
|
|
mem_cgroup_cancel_charge(page, memcg, true);
|
|
put_page(page);
|
|
return VM_FAULT_OOM;
|
|
}
|
|
|
|
clear_huge_page(page, haddr, HPAGE_PMD_NR);
|
|
/*
|
|
* The memory barrier inside __SetPageUptodate makes sure that
|
|
* clear_huge_page writes become visible before the set_pmd_at()
|
|
* write.
|
|
*/
|
|
__SetPageUptodate(page);
|
|
|
|
ptl = pmd_lock(mm, pmd);
|
|
if (unlikely(!pmd_none(*pmd))) {
|
|
spin_unlock(ptl);
|
|
mem_cgroup_cancel_charge(page, memcg, true);
|
|
put_page(page);
|
|
pte_free(mm, pgtable);
|
|
} else {
|
|
pmd_t entry;
|
|
|
|
/* Deliver the page fault to userland */
|
|
if (userfaultfd_missing(vma)) {
|
|
int ret;
|
|
|
|
spin_unlock(ptl);
|
|
mem_cgroup_cancel_charge(page, memcg, true);
|
|
put_page(page);
|
|
pte_free(mm, pgtable);
|
|
ret = handle_userfault(vma, address, flags,
|
|
VM_UFFD_MISSING);
|
|
VM_BUG_ON(ret & VM_FAULT_FALLBACK);
|
|
return ret;
|
|
}
|
|
|
|
entry = mk_huge_pmd(page, vma->vm_page_prot);
|
|
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
|
|
page_add_new_anon_rmap(page, vma, haddr, true);
|
|
mem_cgroup_commit_charge(page, memcg, false, true);
|
|
lru_cache_add_active_or_unevictable(page, vma);
|
|
pgtable_trans_huge_deposit(mm, pmd, pgtable);
|
|
set_pmd_at(mm, haddr, pmd, entry);
|
|
add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
|
|
atomic_long_inc(&mm->nr_ptes);
|
|
spin_unlock(ptl);
|
|
count_vm_event(THP_FAULT_ALLOC);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* If THP is set to always then directly reclaim/compact as necessary
|
|
* If set to defer then do no reclaim and defer to khugepaged
|
|
* If set to madvise and the VMA is flagged then directly reclaim/compact
|
|
*/
|
|
static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
|
|
{
|
|
gfp_t reclaim_flags = 0;
|
|
|
|
if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags) &&
|
|
(vma->vm_flags & VM_HUGEPAGE))
|
|
reclaim_flags = __GFP_DIRECT_RECLAIM;
|
|
else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
|
|
reclaim_flags = __GFP_KSWAPD_RECLAIM;
|
|
else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
|
|
reclaim_flags = __GFP_DIRECT_RECLAIM;
|
|
|
|
return GFP_TRANSHUGE | reclaim_flags;
|
|
}
|
|
|
|
/* Defrag for khugepaged will enter direct reclaim/compaction if necessary */
|
|
static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void)
|
|
{
|
|
return GFP_TRANSHUGE | (khugepaged_defrag() ? __GFP_DIRECT_RECLAIM : 0);
|
|
}
|
|
|
|
/* Caller must hold page table lock. */
|
|
static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
|
|
struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
|
|
struct page *zero_page)
|
|
{
|
|
pmd_t entry;
|
|
if (!pmd_none(*pmd))
|
|
return false;
|
|
entry = mk_pmd(zero_page, vma->vm_page_prot);
|
|
entry = pmd_mkhuge(entry);
|
|
if (pgtable)
|
|
pgtable_trans_huge_deposit(mm, pmd, pgtable);
|
|
set_pmd_at(mm, haddr, pmd, entry);
|
|
atomic_long_inc(&mm->nr_ptes);
|
|
return true;
|
|
}
|
|
|
|
int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long address, pmd_t *pmd,
|
|
unsigned int flags)
|
|
{
|
|
gfp_t gfp;
|
|
struct page *page;
|
|
unsigned long haddr = address & HPAGE_PMD_MASK;
|
|
|
|
if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
|
|
return VM_FAULT_FALLBACK;
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return VM_FAULT_OOM;
|
|
if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
|
|
return VM_FAULT_OOM;
|
|
if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) &&
|
|
transparent_hugepage_use_zero_page()) {
|
|
spinlock_t *ptl;
|
|
pgtable_t pgtable;
|
|
struct page *zero_page;
|
|
bool set;
|
|
int ret;
|
|
pgtable = pte_alloc_one(mm, haddr);
|
|
if (unlikely(!pgtable))
|
|
return VM_FAULT_OOM;
|
|
zero_page = get_huge_zero_page();
|
|
if (unlikely(!zero_page)) {
|
|
pte_free(mm, pgtable);
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
ptl = pmd_lock(mm, pmd);
|
|
ret = 0;
|
|
set = false;
|
|
if (pmd_none(*pmd)) {
|
|
if (userfaultfd_missing(vma)) {
|
|
spin_unlock(ptl);
|
|
ret = handle_userfault(vma, address, flags,
|
|
VM_UFFD_MISSING);
|
|
VM_BUG_ON(ret & VM_FAULT_FALLBACK);
|
|
} else {
|
|
set_huge_zero_page(pgtable, mm, vma,
|
|
haddr, pmd,
|
|
zero_page);
|
|
spin_unlock(ptl);
|
|
set = true;
|
|
}
|
|
} else
|
|
spin_unlock(ptl);
|
|
if (!set) {
|
|
pte_free(mm, pgtable);
|
|
put_huge_zero_page();
|
|
}
|
|
return ret;
|
|
}
|
|
gfp = alloc_hugepage_direct_gfpmask(vma);
|
|
page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
|
|
if (unlikely(!page)) {
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
prep_transhuge_page(page);
|
|
return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp,
|
|
flags);
|
|
}
|
|
|
|
static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
|
|
pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pmd_t entry;
|
|
spinlock_t *ptl;
|
|
|
|
ptl = pmd_lock(mm, pmd);
|
|
entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
|
|
if (pfn_t_devmap(pfn))
|
|
entry = pmd_mkdevmap(entry);
|
|
if (write) {
|
|
entry = pmd_mkyoung(pmd_mkdirty(entry));
|
|
entry = maybe_pmd_mkwrite(entry, vma);
|
|
}
|
|
set_pmd_at(mm, addr, pmd, entry);
|
|
update_mmu_cache_pmd(vma, addr, pmd);
|
|
spin_unlock(ptl);
|
|
}
|
|
|
|
int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
|
|
pmd_t *pmd, pfn_t pfn, bool write)
|
|
{
|
|
pgprot_t pgprot = vma->vm_page_prot;
|
|
/*
|
|
* If we had pmd_special, we could avoid all these restrictions,
|
|
* but we need to be consistent with PTEs and architectures that
|
|
* can't support a 'special' bit.
|
|
*/
|
|
BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
|
|
BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
|
|
(VM_PFNMAP|VM_MIXEDMAP));
|
|
BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
|
|
BUG_ON(!pfn_t_devmap(pfn));
|
|
|
|
if (addr < vma->vm_start || addr >= vma->vm_end)
|
|
return VM_FAULT_SIGBUS;
|
|
if (track_pfn_insert(vma, &pgprot, pfn))
|
|
return VM_FAULT_SIGBUS;
|
|
insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
|
|
return VM_FAULT_NOPAGE;
|
|
}
|
|
|
|
static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
|
|
pmd_t *pmd)
|
|
{
|
|
pmd_t _pmd;
|
|
|
|
/*
|
|
* We should set the dirty bit only for FOLL_WRITE but for now
|
|
* the dirty bit in the pmd is meaningless. And if the dirty
|
|
* bit will become meaningful and we'll only set it with
|
|
* FOLL_WRITE, an atomic set_bit will be required on the pmd to
|
|
* set the young bit, instead of the current set_pmd_at.
|
|
*/
|
|
_pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
|
|
if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
|
|
pmd, _pmd, 1))
|
|
update_mmu_cache_pmd(vma, addr, pmd);
|
|
}
|
|
|
|
struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
|
|
pmd_t *pmd, int flags)
|
|
{
|
|
unsigned long pfn = pmd_pfn(*pmd);
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct dev_pagemap *pgmap;
|
|
struct page *page;
|
|
|
|
assert_spin_locked(pmd_lockptr(mm, pmd));
|
|
|
|
if (flags & FOLL_WRITE && !pmd_write(*pmd))
|
|
return NULL;
|
|
|
|
if (pmd_present(*pmd) && pmd_devmap(*pmd))
|
|
/* pass */;
|
|
else
|
|
return NULL;
|
|
|
|
if (flags & FOLL_TOUCH)
|
|
touch_pmd(vma, addr, pmd);
|
|
|
|
/*
|
|
* device mapped pages can only be returned if the
|
|
* caller will manage the page reference count.
|
|
*/
|
|
if (!(flags & FOLL_GET))
|
|
return ERR_PTR(-EEXIST);
|
|
|
|
pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
|
|
pgmap = get_dev_pagemap(pfn, NULL);
|
|
if (!pgmap)
|
|
return ERR_PTR(-EFAULT);
|
|
page = pfn_to_page(pfn);
|
|
get_page(page);
|
|
put_dev_pagemap(pgmap);
|
|
|
|
return page;
|
|
}
|
|
|
|
int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
|
|
pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
spinlock_t *dst_ptl, *src_ptl;
|
|
struct page *src_page;
|
|
pmd_t pmd;
|
|
pgtable_t pgtable = NULL;
|
|
int ret;
|
|
|
|
if (!vma_is_dax(vma)) {
|
|
ret = -ENOMEM;
|
|
pgtable = pte_alloc_one(dst_mm, addr);
|
|
if (unlikely(!pgtable))
|
|
goto out;
|
|
}
|
|
|
|
dst_ptl = pmd_lock(dst_mm, dst_pmd);
|
|
src_ptl = pmd_lockptr(src_mm, src_pmd);
|
|
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
|
|
|
|
ret = -EAGAIN;
|
|
pmd = *src_pmd;
|
|
if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) {
|
|
pte_free(dst_mm, pgtable);
|
|
goto out_unlock;
|
|
}
|
|
/*
|
|
* When page table lock is held, the huge zero pmd should not be
|
|
* under splitting since we don't split the page itself, only pmd to
|
|
* a page table.
|
|
*/
|
|
if (is_huge_zero_pmd(pmd)) {
|
|
struct page *zero_page;
|
|
/*
|
|
* get_huge_zero_page() will never allocate a new page here,
|
|
* since we already have a zero page to copy. It just takes a
|
|
* reference.
|
|
*/
|
|
zero_page = get_huge_zero_page();
|
|
set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
|
|
zero_page);
|
|
ret = 0;
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (!vma_is_dax(vma)) {
|
|
/* thp accounting separate from pmd_devmap accounting */
|
|
src_page = pmd_page(pmd);
|
|
VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
|
|
get_page(src_page);
|
|
page_dup_rmap(src_page, true);
|
|
add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
|
|
atomic_long_inc(&dst_mm->nr_ptes);
|
|
pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
|
|
}
|
|
|
|
pmdp_set_wrprotect(src_mm, addr, src_pmd);
|
|
pmd = pmd_mkold(pmd_wrprotect(pmd));
|
|
set_pmd_at(dst_mm, addr, dst_pmd, pmd);
|
|
|
|
ret = 0;
|
|
out_unlock:
|
|
spin_unlock(src_ptl);
|
|
spin_unlock(dst_ptl);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
void huge_pmd_set_accessed(struct mm_struct *mm,
|
|
struct vm_area_struct *vma,
|
|
unsigned long address,
|
|
pmd_t *pmd, pmd_t orig_pmd,
|
|
int dirty)
|
|
{
|
|
spinlock_t *ptl;
|
|
pmd_t entry;
|
|
unsigned long haddr;
|
|
|
|
ptl = pmd_lock(mm, pmd);
|
|
if (unlikely(!pmd_same(*pmd, orig_pmd)))
|
|
goto unlock;
|
|
|
|
entry = pmd_mkyoung(orig_pmd);
|
|
haddr = address & HPAGE_PMD_MASK;
|
|
if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
|
|
update_mmu_cache_pmd(vma, address, pmd);
|
|
|
|
unlock:
|
|
spin_unlock(ptl);
|
|
}
|
|
|
|
static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
|
|
struct vm_area_struct *vma,
|
|
unsigned long address,
|
|
pmd_t *pmd, pmd_t orig_pmd,
|
|
struct page *page,
|
|
unsigned long haddr)
|
|
{
|
|
struct mem_cgroup *memcg;
|
|
spinlock_t *ptl;
|
|
pgtable_t pgtable;
|
|
pmd_t _pmd;
|
|
int ret = 0, i;
|
|
struct page **pages;
|
|
unsigned long mmun_start; /* For mmu_notifiers */
|
|
unsigned long mmun_end; /* For mmu_notifiers */
|
|
|
|
pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
|
|
GFP_KERNEL);
|
|
if (unlikely(!pages)) {
|
|
ret |= VM_FAULT_OOM;
|
|
goto out;
|
|
}
|
|
|
|
for (i = 0; i < HPAGE_PMD_NR; i++) {
|
|
pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
|
|
__GFP_OTHER_NODE,
|
|
vma, address, page_to_nid(page));
|
|
if (unlikely(!pages[i] ||
|
|
mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
|
|
&memcg, false))) {
|
|
if (pages[i])
|
|
put_page(pages[i]);
|
|
while (--i >= 0) {
|
|
memcg = (void *)page_private(pages[i]);
|
|
set_page_private(pages[i], 0);
|
|
mem_cgroup_cancel_charge(pages[i], memcg,
|
|
false);
|
|
put_page(pages[i]);
|
|
}
|
|
kfree(pages);
|
|
ret |= VM_FAULT_OOM;
|
|
goto out;
|
|
}
|
|
set_page_private(pages[i], (unsigned long)memcg);
|
|
}
|
|
|
|
for (i = 0; i < HPAGE_PMD_NR; i++) {
|
|
copy_user_highpage(pages[i], page + i,
|
|
haddr + PAGE_SIZE * i, vma);
|
|
__SetPageUptodate(pages[i]);
|
|
cond_resched();
|
|
}
|
|
|
|
mmun_start = haddr;
|
|
mmun_end = haddr + HPAGE_PMD_SIZE;
|
|
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
|
|
|
|
ptl = pmd_lock(mm, pmd);
|
|
if (unlikely(!pmd_same(*pmd, orig_pmd)))
|
|
goto out_free_pages;
|
|
VM_BUG_ON_PAGE(!PageHead(page), page);
|
|
|
|
pmdp_huge_clear_flush_notify(vma, haddr, pmd);
|
|
/* leave pmd empty until pte is filled */
|
|
|
|
pgtable = pgtable_trans_huge_withdraw(mm, pmd);
|
|
pmd_populate(mm, &_pmd, pgtable);
|
|
|
|
for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
|
|
pte_t *pte, entry;
|
|
entry = mk_pte(pages[i], vma->vm_page_prot);
|
|
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
|
|
memcg = (void *)page_private(pages[i]);
|
|
set_page_private(pages[i], 0);
|
|
page_add_new_anon_rmap(pages[i], vma, haddr, false);
|
|
mem_cgroup_commit_charge(pages[i], memcg, false, false);
|
|
lru_cache_add_active_or_unevictable(pages[i], vma);
|
|
pte = pte_offset_map(&_pmd, haddr);
|
|
VM_BUG_ON(!pte_none(*pte));
|
|
set_pte_at(mm, haddr, pte, entry);
|
|
pte_unmap(pte);
|
|
}
|
|
kfree(pages);
|
|
|
|
smp_wmb(); /* make pte visible before pmd */
|
|
pmd_populate(mm, pmd, pgtable);
|
|
page_remove_rmap(page, true);
|
|
spin_unlock(ptl);
|
|
|
|
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
|
|
|
|
ret |= VM_FAULT_WRITE;
|
|
put_page(page);
|
|
|
|
out:
|
|
return ret;
|
|
|
|
out_free_pages:
|
|
spin_unlock(ptl);
|
|
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
|
|
for (i = 0; i < HPAGE_PMD_NR; i++) {
|
|
memcg = (void *)page_private(pages[i]);
|
|
set_page_private(pages[i], 0);
|
|
mem_cgroup_cancel_charge(pages[i], memcg, false);
|
|
put_page(pages[i]);
|
|
}
|
|
kfree(pages);
|
|
goto out;
|
|
}
|
|
|
|
int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
|
|
{
|
|
spinlock_t *ptl;
|
|
int ret = 0;
|
|
struct page *page = NULL, *new_page;
|
|
struct mem_cgroup *memcg;
|
|
unsigned long haddr;
|
|
unsigned long mmun_start; /* For mmu_notifiers */
|
|
unsigned long mmun_end; /* For mmu_notifiers */
|
|
gfp_t huge_gfp; /* for allocation and charge */
|
|
|
|
ptl = pmd_lockptr(mm, pmd);
|
|
VM_BUG_ON_VMA(!vma->anon_vma, vma);
|
|
haddr = address & HPAGE_PMD_MASK;
|
|
if (is_huge_zero_pmd(orig_pmd))
|
|
goto alloc;
|
|
spin_lock(ptl);
|
|
if (unlikely(!pmd_same(*pmd, orig_pmd)))
|
|
goto out_unlock;
|
|
|
|
page = pmd_page(orig_pmd);
|
|
VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
|
|
/*
|
|
* We can only reuse the page if nobody else maps the huge page or it's
|
|
* part.
|
|
*/
|
|
if (page_trans_huge_mapcount(page, NULL) == 1) {
|
|
pmd_t entry;
|
|
entry = pmd_mkyoung(orig_pmd);
|
|
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
|
|
if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
|
|
update_mmu_cache_pmd(vma, address, pmd);
|
|
ret |= VM_FAULT_WRITE;
|
|
goto out_unlock;
|
|
}
|
|
get_page(page);
|
|
spin_unlock(ptl);
|
|
alloc:
|
|
if (transparent_hugepage_enabled(vma) &&
|
|
!transparent_hugepage_debug_cow()) {
|
|
huge_gfp = alloc_hugepage_direct_gfpmask(vma);
|
|
new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
|
|
} else
|
|
new_page = NULL;
|
|
|
|
if (likely(new_page)) {
|
|
prep_transhuge_page(new_page);
|
|
} else {
|
|
if (!page) {
|
|
split_huge_pmd(vma, pmd, address);
|
|
ret |= VM_FAULT_FALLBACK;
|
|
} else {
|
|
ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
|
|
pmd, orig_pmd, page, haddr);
|
|
if (ret & VM_FAULT_OOM) {
|
|
split_huge_pmd(vma, pmd, address);
|
|
ret |= VM_FAULT_FALLBACK;
|
|
}
|
|
put_page(page);
|
|
}
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
goto out;
|
|
}
|
|
|
|
if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg,
|
|
true))) {
|
|
put_page(new_page);
|
|
if (page) {
|
|
split_huge_pmd(vma, pmd, address);
|
|
put_page(page);
|
|
} else
|
|
split_huge_pmd(vma, pmd, address);
|
|
ret |= VM_FAULT_FALLBACK;
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
goto out;
|
|
}
|
|
|
|
count_vm_event(THP_FAULT_ALLOC);
|
|
|
|
if (!page)
|
|
clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
|
|
else
|
|
copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
|
|
__SetPageUptodate(new_page);
|
|
|
|
mmun_start = haddr;
|
|
mmun_end = haddr + HPAGE_PMD_SIZE;
|
|
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
|
|
|
|
spin_lock(ptl);
|
|
if (page)
|
|
put_page(page);
|
|
if (unlikely(!pmd_same(*pmd, orig_pmd))) {
|
|
spin_unlock(ptl);
|
|
mem_cgroup_cancel_charge(new_page, memcg, true);
|
|
put_page(new_page);
|
|
goto out_mn;
|
|
} else {
|
|
pmd_t entry;
|
|
entry = mk_huge_pmd(new_page, vma->vm_page_prot);
|
|
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
|
|
pmdp_huge_clear_flush_notify(vma, haddr, pmd);
|
|
page_add_new_anon_rmap(new_page, vma, haddr, true);
|
|
mem_cgroup_commit_charge(new_page, memcg, false, true);
|
|
lru_cache_add_active_or_unevictable(new_page, vma);
|
|
set_pmd_at(mm, haddr, pmd, entry);
|
|
update_mmu_cache_pmd(vma, address, pmd);
|
|
if (!page) {
|
|
add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
|
|
put_huge_zero_page();
|
|
} else {
|
|
VM_BUG_ON_PAGE(!PageHead(page), page);
|
|
page_remove_rmap(page, true);
|
|
put_page(page);
|
|
}
|
|
ret |= VM_FAULT_WRITE;
|
|
}
|
|
spin_unlock(ptl);
|
|
out_mn:
|
|
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
|
|
out:
|
|
return ret;
|
|
out_unlock:
|
|
spin_unlock(ptl);
|
|
return ret;
|
|
}
|
|
|
|
struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
|
|
unsigned long addr,
|
|
pmd_t *pmd,
|
|
unsigned int flags)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page *page = NULL;
|
|
|
|
assert_spin_locked(pmd_lockptr(mm, pmd));
|
|
|
|
if (flags & FOLL_WRITE && !pmd_write(*pmd))
|
|
goto out;
|
|
|
|
/* Avoid dumping huge zero page */
|
|
if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
|
|
return ERR_PTR(-EFAULT);
|
|
|
|
/* Full NUMA hinting faults to serialise migration in fault paths */
|
|
if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
|
|
goto out;
|
|
|
|
page = pmd_page(*pmd);
|
|
VM_BUG_ON_PAGE(!PageHead(page), page);
|
|
if (flags & FOLL_TOUCH)
|
|
touch_pmd(vma, addr, pmd);
|
|
if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
|
|
/*
|
|
* We don't mlock() pte-mapped THPs. This way we can avoid
|
|
* leaking mlocked pages into non-VM_LOCKED VMAs.
|
|
*
|
|
* In most cases the pmd is the only mapping of the page as we
|
|
* break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
|
|
* writable private mappings in populate_vma_page_range().
|
|
*
|
|
* The only scenario when we have the page shared here is if we
|
|
* mlocking read-only mapping shared over fork(). We skip
|
|
* mlocking such pages.
|
|
*/
|
|
if (compound_mapcount(page) == 1 && !PageDoubleMap(page) &&
|
|
page->mapping && trylock_page(page)) {
|
|
lru_add_drain();
|
|
if (page->mapping)
|
|
mlock_vma_page(page);
|
|
unlock_page(page);
|
|
}
|
|
}
|
|
page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
|
|
VM_BUG_ON_PAGE(!PageCompound(page), page);
|
|
if (flags & FOLL_GET)
|
|
get_page(page);
|
|
|
|
out:
|
|
return page;
|
|
}
|
|
|
|
/* NUMA hinting page fault entry point for trans huge pmds */
|
|
int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long addr, pmd_t pmd, pmd_t *pmdp)
|
|
{
|
|
spinlock_t *ptl;
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct page *page;
|
|
unsigned long haddr = addr & HPAGE_PMD_MASK;
|
|
int page_nid = -1, this_nid = numa_node_id();
|
|
int target_nid, last_cpupid = -1;
|
|
bool page_locked;
|
|
bool migrated = false;
|
|
bool was_writable;
|
|
int flags = 0;
|
|
|
|
/* A PROT_NONE fault should not end up here */
|
|
BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
|
|
|
|
ptl = pmd_lock(mm, pmdp);
|
|
if (unlikely(!pmd_same(pmd, *pmdp)))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* If there are potential migrations, wait for completion and retry
|
|
* without disrupting NUMA hinting information. Do not relock and
|
|
* check_same as the page may no longer be mapped.
|
|
*/
|
|
if (unlikely(pmd_trans_migrating(*pmdp))) {
|
|
page = pmd_page(*pmdp);
|
|
spin_unlock(ptl);
|
|
wait_on_page_locked(page);
|
|
goto out;
|
|
}
|
|
|
|
page = pmd_page(pmd);
|
|
BUG_ON(is_huge_zero_page(page));
|
|
page_nid = page_to_nid(page);
|
|
last_cpupid = page_cpupid_last(page);
|
|
count_vm_numa_event(NUMA_HINT_FAULTS);
|
|
if (page_nid == this_nid) {
|
|
count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
|
|
flags |= TNF_FAULT_LOCAL;
|
|
}
|
|
|
|
/* See similar comment in do_numa_page for explanation */
|
|
if (!(vma->vm_flags & VM_WRITE))
|
|
flags |= TNF_NO_GROUP;
|
|
|
|
/*
|
|
* Acquire the page lock to serialise THP migrations but avoid dropping
|
|
* page_table_lock if at all possible
|
|
*/
|
|
page_locked = trylock_page(page);
|
|
target_nid = mpol_misplaced(page, vma, haddr);
|
|
if (target_nid == -1) {
|
|
/* If the page was locked, there are no parallel migrations */
|
|
if (page_locked)
|
|
goto clear_pmdnuma;
|
|
}
|
|
|
|
/* Migration could have started since the pmd_trans_migrating check */
|
|
if (!page_locked) {
|
|
spin_unlock(ptl);
|
|
wait_on_page_locked(page);
|
|
page_nid = -1;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Page is misplaced. Page lock serialises migrations. Acquire anon_vma
|
|
* to serialises splits
|
|
*/
|
|
get_page(page);
|
|
spin_unlock(ptl);
|
|
anon_vma = page_lock_anon_vma_read(page);
|
|
|
|
/* Confirm the PMD did not change while page_table_lock was released */
|
|
spin_lock(ptl);
|
|
if (unlikely(!pmd_same(pmd, *pmdp))) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
page_nid = -1;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* Bail if we fail to protect against THP splits for any reason */
|
|
if (unlikely(!anon_vma)) {
|
|
put_page(page);
|
|
page_nid = -1;
|
|
goto clear_pmdnuma;
|
|
}
|
|
|
|
/*
|
|
* Migrate the THP to the requested node, returns with page unlocked
|
|
* and access rights restored.
|
|
*/
|
|
spin_unlock(ptl);
|
|
migrated = migrate_misplaced_transhuge_page(mm, vma,
|
|
pmdp, pmd, addr, page, target_nid);
|
|
if (migrated) {
|
|
flags |= TNF_MIGRATED;
|
|
page_nid = target_nid;
|
|
} else
|
|
flags |= TNF_MIGRATE_FAIL;
|
|
|
|
goto out;
|
|
clear_pmdnuma:
|
|
BUG_ON(!PageLocked(page));
|
|
was_writable = pmd_write(pmd);
|
|
pmd = pmd_modify(pmd, vma->vm_page_prot);
|
|
pmd = pmd_mkyoung(pmd);
|
|
if (was_writable)
|
|
pmd = pmd_mkwrite(pmd);
|
|
set_pmd_at(mm, haddr, pmdp, pmd);
|
|
update_mmu_cache_pmd(vma, addr, pmdp);
|
|
unlock_page(page);
|
|
out_unlock:
|
|
spin_unlock(ptl);
|
|
|
|
out:
|
|
if (anon_vma)
|
|
page_unlock_anon_vma_read(anon_vma);
|
|
|
|
if (page_nid != -1)
|
|
task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
|
|
pmd_t *pmd, unsigned long addr, unsigned long next)
|
|
|
|
{
|
|
spinlock_t *ptl;
|
|
pmd_t orig_pmd;
|
|
struct page *page;
|
|
struct mm_struct *mm = tlb->mm;
|
|
int ret = 0;
|
|
|
|
ptl = pmd_trans_huge_lock(pmd, vma);
|
|
if (!ptl)
|
|
goto out_unlocked;
|
|
|
|
orig_pmd = *pmd;
|
|
if (is_huge_zero_pmd(orig_pmd)) {
|
|
ret = 1;
|
|
goto out;
|
|
}
|
|
|
|
page = pmd_page(orig_pmd);
|
|
/*
|
|
* If other processes are mapping this page, we couldn't discard
|
|
* the page unless they all do MADV_FREE so let's skip the page.
|
|
*/
|
|
if (page_mapcount(page) != 1)
|
|
goto out;
|
|
|
|
if (!trylock_page(page))
|
|
goto out;
|
|
|
|
/*
|
|
* If user want to discard part-pages of THP, split it so MADV_FREE
|
|
* will deactivate only them.
|
|
*/
|
|
if (next - addr != HPAGE_PMD_SIZE) {
|
|
get_page(page);
|
|
spin_unlock(ptl);
|
|
if (split_huge_page(page)) {
|
|
put_page(page);
|
|
unlock_page(page);
|
|
goto out_unlocked;
|
|
}
|
|
put_page(page);
|
|
unlock_page(page);
|
|
ret = 1;
|
|
goto out_unlocked;
|
|
}
|
|
|
|
if (PageDirty(page))
|
|
ClearPageDirty(page);
|
|
unlock_page(page);
|
|
|
|
if (PageActive(page))
|
|
deactivate_page(page);
|
|
|
|
if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
|
|
orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
|
|
tlb->fullmm);
|
|
orig_pmd = pmd_mkold(orig_pmd);
|
|
orig_pmd = pmd_mkclean(orig_pmd);
|
|
|
|
set_pmd_at(mm, addr, pmd, orig_pmd);
|
|
tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
|
|
}
|
|
ret = 1;
|
|
out:
|
|
spin_unlock(ptl);
|
|
out_unlocked:
|
|
return ret;
|
|
}
|
|
|
|
int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
|
|
pmd_t *pmd, unsigned long addr)
|
|
{
|
|
pmd_t orig_pmd;
|
|
spinlock_t *ptl;
|
|
|
|
ptl = __pmd_trans_huge_lock(pmd, vma);
|
|
if (!ptl)
|
|
return 0;
|
|
/*
|
|
* For architectures like ppc64 we look at deposited pgtable
|
|
* when calling pmdp_huge_get_and_clear. So do the
|
|
* pgtable_trans_huge_withdraw after finishing pmdp related
|
|
* operations.
|
|
*/
|
|
orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
|
|
tlb->fullmm);
|
|
tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
|
|
if (vma_is_dax(vma)) {
|
|
spin_unlock(ptl);
|
|
if (is_huge_zero_pmd(orig_pmd))
|
|
tlb_remove_page(tlb, pmd_page(orig_pmd));
|
|
} else if (is_huge_zero_pmd(orig_pmd)) {
|
|
pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
|
|
atomic_long_dec(&tlb->mm->nr_ptes);
|
|
spin_unlock(ptl);
|
|
tlb_remove_page(tlb, pmd_page(orig_pmd));
|
|
} else {
|
|
struct page *page = pmd_page(orig_pmd);
|
|
page_remove_rmap(page, true);
|
|
VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
|
|
add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
|
|
VM_BUG_ON_PAGE(!PageHead(page), page);
|
|
pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
|
|
atomic_long_dec(&tlb->mm->nr_ptes);
|
|
spin_unlock(ptl);
|
|
tlb_remove_page(tlb, page);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
bool move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
|
|
unsigned long old_addr,
|
|
unsigned long new_addr, unsigned long old_end,
|
|
pmd_t *old_pmd, pmd_t *new_pmd)
|
|
{
|
|
spinlock_t *old_ptl, *new_ptl;
|
|
pmd_t pmd;
|
|
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
|
|
if ((old_addr & ~HPAGE_PMD_MASK) ||
|
|
(new_addr & ~HPAGE_PMD_MASK) ||
|
|
old_end - old_addr < HPAGE_PMD_SIZE ||
|
|
(new_vma->vm_flags & VM_NOHUGEPAGE))
|
|
return false;
|
|
|
|
/*
|
|
* The destination pmd shouldn't be established, free_pgtables()
|
|
* should have release it.
|
|
*/
|
|
if (WARN_ON(!pmd_none(*new_pmd))) {
|
|
VM_BUG_ON(pmd_trans_huge(*new_pmd));
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* We don't have to worry about the ordering of src and dst
|
|
* ptlocks because exclusive mmap_sem prevents deadlock.
|
|
*/
|
|
old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
|
|
if (old_ptl) {
|
|
new_ptl = pmd_lockptr(mm, new_pmd);
|
|
if (new_ptl != old_ptl)
|
|
spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
|
|
pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
|
|
VM_BUG_ON(!pmd_none(*new_pmd));
|
|
|
|
if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
|
|
vma_is_anonymous(vma)) {
|
|
pgtable_t pgtable;
|
|
pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
|
|
pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
|
|
}
|
|
set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
|
|
if (new_ptl != old_ptl)
|
|
spin_unlock(new_ptl);
|
|
spin_unlock(old_ptl);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Returns
|
|
* - 0 if PMD could not be locked
|
|
* - 1 if PMD was locked but protections unchange and TLB flush unnecessary
|
|
* - HPAGE_PMD_NR is protections changed and TLB flush necessary
|
|
*/
|
|
int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long addr, pgprot_t newprot, int prot_numa)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
spinlock_t *ptl;
|
|
int ret = 0;
|
|
|
|
ptl = __pmd_trans_huge_lock(pmd, vma);
|
|
if (ptl) {
|
|
pmd_t entry;
|
|
bool preserve_write = prot_numa && pmd_write(*pmd);
|
|
ret = 1;
|
|
|
|
/*
|
|
* Avoid trapping faults against the zero page. The read-only
|
|
* data is likely to be read-cached on the local CPU and
|
|
* local/remote hits to the zero page are not interesting.
|
|
*/
|
|
if (prot_numa && is_huge_zero_pmd(*pmd)) {
|
|
spin_unlock(ptl);
|
|
return ret;
|
|
}
|
|
|
|
if (!prot_numa || !pmd_protnone(*pmd)) {
|
|
entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd);
|
|
entry = pmd_modify(entry, newprot);
|
|
if (preserve_write)
|
|
entry = pmd_mkwrite(entry);
|
|
ret = HPAGE_PMD_NR;
|
|
set_pmd_at(mm, addr, pmd, entry);
|
|
BUG_ON(!preserve_write && pmd_write(entry));
|
|
}
|
|
spin_unlock(ptl);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Returns true if a given pmd maps a thp, false otherwise.
|
|
*
|
|
* Note that if it returns true, this routine returns without unlocking page
|
|
* table lock. So callers must unlock it.
|
|
*/
|
|
spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
|
|
{
|
|
spinlock_t *ptl;
|
|
ptl = pmd_lock(vma->vm_mm, pmd);
|
|
if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd)))
|
|
return ptl;
|
|
spin_unlock(ptl);
|
|
return NULL;
|
|
}
|
|
|
|
#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
|
|
|
|
int hugepage_madvise(struct vm_area_struct *vma,
|
|
unsigned long *vm_flags, int advice)
|
|
{
|
|
switch (advice) {
|
|
case MADV_HUGEPAGE:
|
|
#ifdef CONFIG_S390
|
|
/*
|
|
* qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
|
|
* can't handle this properly after s390_enable_sie, so we simply
|
|
* ignore the madvise to prevent qemu from causing a SIGSEGV.
|
|
*/
|
|
if (mm_has_pgste(vma->vm_mm))
|
|
return 0;
|
|
#endif
|
|
/*
|
|
* Be somewhat over-protective like KSM for now!
|
|
*/
|
|
if (*vm_flags & VM_NO_THP)
|
|
return -EINVAL;
|
|
*vm_flags &= ~VM_NOHUGEPAGE;
|
|
*vm_flags |= VM_HUGEPAGE;
|
|
/*
|
|
* If the vma become good for khugepaged to scan,
|
|
* register it here without waiting a page fault that
|
|
* may not happen any time soon.
|
|
*/
|
|
if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
|
|
return -ENOMEM;
|
|
break;
|
|
case MADV_NOHUGEPAGE:
|
|
/*
|
|
* Be somewhat over-protective like KSM for now!
|
|
*/
|
|
if (*vm_flags & VM_NO_THP)
|
|
return -EINVAL;
|
|
*vm_flags &= ~VM_HUGEPAGE;
|
|
*vm_flags |= VM_NOHUGEPAGE;
|
|
/*
|
|
* Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
|
|
* this vma even if we leave the mm registered in khugepaged if
|
|
* it got registered before VM_NOHUGEPAGE was set.
|
|
*/
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __init khugepaged_slab_init(void)
|
|
{
|
|
mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
|
|
sizeof(struct mm_slot),
|
|
__alignof__(struct mm_slot), 0, NULL);
|
|
if (!mm_slot_cache)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __init khugepaged_slab_exit(void)
|
|
{
|
|
kmem_cache_destroy(mm_slot_cache);
|
|
}
|
|
|
|
static inline struct mm_slot *alloc_mm_slot(void)
|
|
{
|
|
if (!mm_slot_cache) /* initialization failed */
|
|
return NULL;
|
|
return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
|
|
}
|
|
|
|
static inline void free_mm_slot(struct mm_slot *mm_slot)
|
|
{
|
|
kmem_cache_free(mm_slot_cache, mm_slot);
|
|
}
|
|
|
|
static struct mm_slot *get_mm_slot(struct mm_struct *mm)
|
|
{
|
|
struct mm_slot *mm_slot;
|
|
|
|
hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
|
|
if (mm == mm_slot->mm)
|
|
return mm_slot;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void insert_to_mm_slots_hash(struct mm_struct *mm,
|
|
struct mm_slot *mm_slot)
|
|
{
|
|
mm_slot->mm = mm;
|
|
hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
|
|
}
|
|
|
|
static inline int khugepaged_test_exit(struct mm_struct *mm)
|
|
{
|
|
return atomic_read(&mm->mm_users) == 0;
|
|
}
|
|
|
|
int __khugepaged_enter(struct mm_struct *mm)
|
|
{
|
|
struct mm_slot *mm_slot;
|
|
int wakeup;
|
|
|
|
mm_slot = alloc_mm_slot();
|
|
if (!mm_slot)
|
|
return -ENOMEM;
|
|
|
|
/* __khugepaged_exit() must not run from under us */
|
|
VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
|
|
if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
|
|
free_mm_slot(mm_slot);
|
|
return 0;
|
|
}
|
|
|
|
spin_lock(&khugepaged_mm_lock);
|
|
insert_to_mm_slots_hash(mm, mm_slot);
|
|
/*
|
|
* Insert just behind the scanning cursor, to let the area settle
|
|
* down a little.
|
|
*/
|
|
wakeup = list_empty(&khugepaged_scan.mm_head);
|
|
list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
|
|
spin_unlock(&khugepaged_mm_lock);
|
|
|
|
atomic_inc(&mm->mm_count);
|
|
if (wakeup)
|
|
wake_up_interruptible(&khugepaged_wait);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
|
|
unsigned long vm_flags)
|
|
{
|
|
unsigned long hstart, hend;
|
|
if (!vma->anon_vma)
|
|
/*
|
|
* Not yet faulted in so we will register later in the
|
|
* page fault if needed.
|
|
*/
|
|
return 0;
|
|
if (vma->vm_ops || (vm_flags & VM_NO_THP))
|
|
/* khugepaged not yet working on file or special mappings */
|
|
return 0;
|
|
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
|
|
hend = vma->vm_end & HPAGE_PMD_MASK;
|
|
if (hstart < hend)
|
|
return khugepaged_enter(vma, vm_flags);
|
|
return 0;
|
|
}
|
|
|
|
void __khugepaged_exit(struct mm_struct *mm)
|
|
{
|
|
struct mm_slot *mm_slot;
|
|
int free = 0;
|
|
|
|
spin_lock(&khugepaged_mm_lock);
|
|
mm_slot = get_mm_slot(mm);
|
|
if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
|
|
hash_del(&mm_slot->hash);
|
|
list_del(&mm_slot->mm_node);
|
|
free = 1;
|
|
}
|
|
spin_unlock(&khugepaged_mm_lock);
|
|
|
|
if (free) {
|
|
clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
|
|
free_mm_slot(mm_slot);
|
|
mmdrop(mm);
|
|
} else if (mm_slot) {
|
|
/*
|
|
* This is required to serialize against
|
|
* khugepaged_test_exit() (which is guaranteed to run
|
|
* under mmap sem read mode). Stop here (after we
|
|
* return all pagetables will be destroyed) until
|
|
* khugepaged has finished working on the pagetables
|
|
* under the mmap_sem.
|
|
*/
|
|
down_write(&mm->mmap_sem);
|
|
up_write(&mm->mmap_sem);
|
|
}
|
|
}
|
|
|
|
static void release_pte_page(struct page *page)
|
|
{
|
|
/* 0 stands for page_is_file_cache(page) == false */
|
|
dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
|
|
unlock_page(page);
|
|
putback_lru_page(page);
|
|
}
|
|
|
|
static void release_pte_pages(pte_t *pte, pte_t *_pte)
|
|
{
|
|
while (--_pte >= pte) {
|
|
pte_t pteval = *_pte;
|
|
if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)))
|
|
release_pte_page(pte_page(pteval));
|
|
}
|
|
}
|
|
|
|
static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
|
|
unsigned long address,
|
|
pte_t *pte)
|
|
{
|
|
struct page *page = NULL;
|
|
pte_t *_pte;
|
|
int none_or_zero = 0, result = 0;
|
|
bool referenced = false, writable = false;
|
|
|
|
for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
|
|
_pte++, address += PAGE_SIZE) {
|
|
pte_t pteval = *_pte;
|
|
if (pte_none(pteval) || (pte_present(pteval) &&
|
|
is_zero_pfn(pte_pfn(pteval)))) {
|
|
if (!userfaultfd_armed(vma) &&
|
|
++none_or_zero <= khugepaged_max_ptes_none) {
|
|
continue;
|
|
} else {
|
|
result = SCAN_EXCEED_NONE_PTE;
|
|
goto out;
|
|
}
|
|
}
|
|
if (!pte_present(pteval)) {
|
|
result = SCAN_PTE_NON_PRESENT;
|
|
goto out;
|
|
}
|
|
page = vm_normal_page(vma, address, pteval);
|
|
if (unlikely(!page)) {
|
|
result = SCAN_PAGE_NULL;
|
|
goto out;
|
|
}
|
|
|
|
VM_BUG_ON_PAGE(PageCompound(page), page);
|
|
VM_BUG_ON_PAGE(!PageAnon(page), page);
|
|
VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
|
|
|
|
/*
|
|
* We can do it before isolate_lru_page because the
|
|
* page can't be freed from under us. NOTE: PG_lock
|
|
* is needed to serialize against split_huge_page
|
|
* when invoked from the VM.
|
|
*/
|
|
if (!trylock_page(page)) {
|
|
result = SCAN_PAGE_LOCK;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* cannot use mapcount: can't collapse if there's a gup pin.
|
|
* The page must only be referenced by the scanned process
|
|
* and page swap cache.
|
|
*/
|
|
if (page_count(page) != 1 + !!PageSwapCache(page)) {
|
|
unlock_page(page);
|
|
result = SCAN_PAGE_COUNT;
|
|
goto out;
|
|
}
|
|
if (pte_write(pteval)) {
|
|
writable = true;
|
|
} else {
|
|
if (PageSwapCache(page) &&
|
|
!reuse_swap_page(page, NULL)) {
|
|
unlock_page(page);
|
|
result = SCAN_SWAP_CACHE_PAGE;
|
|
goto out;
|
|
}
|
|
/*
|
|
* Page is not in the swap cache. It can be collapsed
|
|
* into a THP.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* Isolate the page to avoid collapsing an hugepage
|
|
* currently in use by the VM.
|
|
*/
|
|
if (isolate_lru_page(page)) {
|
|
unlock_page(page);
|
|
result = SCAN_DEL_PAGE_LRU;
|
|
goto out;
|
|
}
|
|
/* 0 stands for page_is_file_cache(page) == false */
|
|
inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
VM_BUG_ON_PAGE(PageLRU(page), page);
|
|
|
|
/* If there is no mapped pte young don't collapse the page */
|
|
if (pte_young(pteval) ||
|
|
page_is_young(page) || PageReferenced(page) ||
|
|
mmu_notifier_test_young(vma->vm_mm, address))
|
|
referenced = true;
|
|
}
|
|
if (likely(writable)) {
|
|
if (likely(referenced)) {
|
|
result = SCAN_SUCCEED;
|
|
trace_mm_collapse_huge_page_isolate(page, none_or_zero,
|
|
referenced, writable, result);
|
|
return 1;
|
|
}
|
|
} else {
|
|
result = SCAN_PAGE_RO;
|
|
}
|
|
|
|
out:
|
|
release_pte_pages(pte, _pte);
|
|
trace_mm_collapse_huge_page_isolate(page, none_or_zero,
|
|
referenced, writable, result);
|
|
return 0;
|
|
}
|
|
|
|
static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
|
|
struct vm_area_struct *vma,
|
|
unsigned long address,
|
|
spinlock_t *ptl)
|
|
{
|
|
pte_t *_pte;
|
|
for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
|
|
pte_t pteval = *_pte;
|
|
struct page *src_page;
|
|
|
|
if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
|
|
clear_user_highpage(page, address);
|
|
add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
|
|
if (is_zero_pfn(pte_pfn(pteval))) {
|
|
/*
|
|
* ptl mostly unnecessary.
|
|
*/
|
|
spin_lock(ptl);
|
|
/*
|
|
* paravirt calls inside pte_clear here are
|
|
* superfluous.
|
|
*/
|
|
pte_clear(vma->vm_mm, address, _pte);
|
|
spin_unlock(ptl);
|
|
}
|
|
} else {
|
|
src_page = pte_page(pteval);
|
|
copy_user_highpage(page, src_page, address, vma);
|
|
VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
|
|
release_pte_page(src_page);
|
|
/*
|
|
* ptl mostly unnecessary, but preempt has to
|
|
* be disabled to update the per-cpu stats
|
|
* inside page_remove_rmap().
|
|
*/
|
|
spin_lock(ptl);
|
|
/*
|
|
* paravirt calls inside pte_clear here are
|
|
* superfluous.
|
|
*/
|
|
pte_clear(vma->vm_mm, address, _pte);
|
|
page_remove_rmap(src_page, false);
|
|
spin_unlock(ptl);
|
|
free_page_and_swap_cache(src_page);
|
|
}
|
|
|
|
address += PAGE_SIZE;
|
|
page++;
|
|
}
|
|
}
|
|
|
|
static void khugepaged_alloc_sleep(void)
|
|
{
|
|
DEFINE_WAIT(wait);
|
|
|
|
add_wait_queue(&khugepaged_wait, &wait);
|
|
freezable_schedule_timeout_interruptible(
|
|
msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
|
|
remove_wait_queue(&khugepaged_wait, &wait);
|
|
}
|
|
|
|
static int khugepaged_node_load[MAX_NUMNODES];
|
|
|
|
static bool khugepaged_scan_abort(int nid)
|
|
{
|
|
int i;
|
|
|
|
/*
|
|
* If zone_reclaim_mode is disabled, then no extra effort is made to
|
|
* allocate memory locally.
|
|
*/
|
|
if (!zone_reclaim_mode)
|
|
return false;
|
|
|
|
/* If there is a count for this node already, it must be acceptable */
|
|
if (khugepaged_node_load[nid])
|
|
return false;
|
|
|
|
for (i = 0; i < MAX_NUMNODES; i++) {
|
|
if (!khugepaged_node_load[i])
|
|
continue;
|
|
if (node_distance(nid, i) > RECLAIM_DISTANCE)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
static int khugepaged_find_target_node(void)
|
|
{
|
|
static int last_khugepaged_target_node = NUMA_NO_NODE;
|
|
int nid, target_node = 0, max_value = 0;
|
|
|
|
/* find first node with max normal pages hit */
|
|
for (nid = 0; nid < MAX_NUMNODES; nid++)
|
|
if (khugepaged_node_load[nid] > max_value) {
|
|
max_value = khugepaged_node_load[nid];
|
|
target_node = nid;
|
|
}
|
|
|
|
/* do some balance if several nodes have the same hit record */
|
|
if (target_node <= last_khugepaged_target_node)
|
|
for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
|
|
nid++)
|
|
if (max_value == khugepaged_node_load[nid]) {
|
|
target_node = nid;
|
|
break;
|
|
}
|
|
|
|
last_khugepaged_target_node = target_node;
|
|
return target_node;
|
|
}
|
|
|
|
static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
|
|
{
|
|
if (IS_ERR(*hpage)) {
|
|
if (!*wait)
|
|
return false;
|
|
|
|
*wait = false;
|
|
*hpage = NULL;
|
|
khugepaged_alloc_sleep();
|
|
} else if (*hpage) {
|
|
put_page(*hpage);
|
|
*hpage = NULL;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static struct page *
|
|
khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
|
|
unsigned long address, int node)
|
|
{
|
|
VM_BUG_ON_PAGE(*hpage, *hpage);
|
|
|
|
/*
|
|
* Before allocating the hugepage, release the mmap_sem read lock.
|
|
* The allocation can take potentially a long time if it involves
|
|
* sync compaction, and we do not need to hold the mmap_sem during
|
|
* that. We will recheck the vma after taking it again in write mode.
|
|
*/
|
|
up_read(&mm->mmap_sem);
|
|
|
|
*hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
|
|
if (unlikely(!*hpage)) {
|
|
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
|
|
*hpage = ERR_PTR(-ENOMEM);
|
|
return NULL;
|
|
}
|
|
|
|
prep_transhuge_page(*hpage);
|
|
count_vm_event(THP_COLLAPSE_ALLOC);
|
|
return *hpage;
|
|
}
|
|
#else
|
|
static int khugepaged_find_target_node(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline struct page *alloc_khugepaged_hugepage(void)
|
|
{
|
|
struct page *page;
|
|
|
|
page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(),
|
|
HPAGE_PMD_ORDER);
|
|
if (page)
|
|
prep_transhuge_page(page);
|
|
return page;
|
|
}
|
|
|
|
static struct page *khugepaged_alloc_hugepage(bool *wait)
|
|
{
|
|
struct page *hpage;
|
|
|
|
do {
|
|
hpage = alloc_khugepaged_hugepage();
|
|
if (!hpage) {
|
|
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
|
|
if (!*wait)
|
|
return NULL;
|
|
|
|
*wait = false;
|
|
khugepaged_alloc_sleep();
|
|
} else
|
|
count_vm_event(THP_COLLAPSE_ALLOC);
|
|
} while (unlikely(!hpage) && likely(khugepaged_enabled()));
|
|
|
|
return hpage;
|
|
}
|
|
|
|
static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
|
|
{
|
|
if (!*hpage)
|
|
*hpage = khugepaged_alloc_hugepage(wait);
|
|
|
|
if (unlikely(!*hpage))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static struct page *
|
|
khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
|
|
unsigned long address, int node)
|
|
{
|
|
up_read(&mm->mmap_sem);
|
|
VM_BUG_ON(!*hpage);
|
|
|
|
return *hpage;
|
|
}
|
|
#endif
|
|
|
|
static bool hugepage_vma_check(struct vm_area_struct *vma)
|
|
{
|
|
if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
|
|
(vma->vm_flags & VM_NOHUGEPAGE))
|
|
return false;
|
|
if (!vma->anon_vma || vma->vm_ops)
|
|
return false;
|
|
if (is_vma_temporary_stack(vma))
|
|
return false;
|
|
return !(vma->vm_flags & VM_NO_THP);
|
|
}
|
|
|
|
static void collapse_huge_page(struct mm_struct *mm,
|
|
unsigned long address,
|
|
struct page **hpage,
|
|
struct vm_area_struct *vma,
|
|
int node)
|
|
{
|
|
pmd_t *pmd, _pmd;
|
|
pte_t *pte;
|
|
pgtable_t pgtable;
|
|
struct page *new_page;
|
|
spinlock_t *pmd_ptl, *pte_ptl;
|
|
int isolated = 0, result = 0;
|
|
unsigned long hstart, hend;
|
|
struct mem_cgroup *memcg;
|
|
unsigned long mmun_start; /* For mmu_notifiers */
|
|
unsigned long mmun_end; /* For mmu_notifiers */
|
|
gfp_t gfp;
|
|
|
|
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
|
|
|
|
/* Only allocate from the target node */
|
|
gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_OTHER_NODE | __GFP_THISNODE;
|
|
|
|
/* release the mmap_sem read lock. */
|
|
new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node);
|
|
if (!new_page) {
|
|
result = SCAN_ALLOC_HUGE_PAGE_FAIL;
|
|
goto out_nolock;
|
|
}
|
|
|
|
if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) {
|
|
result = SCAN_CGROUP_CHARGE_FAIL;
|
|
goto out_nolock;
|
|
}
|
|
|
|
/*
|
|
* Prevent all access to pagetables with the exception of
|
|
* gup_fast later hanlded by the ptep_clear_flush and the VM
|
|
* handled by the anon_vma lock + PG_lock.
|
|
*/
|
|
down_write(&mm->mmap_sem);
|
|
if (unlikely(khugepaged_test_exit(mm))) {
|
|
result = SCAN_ANY_PROCESS;
|
|
goto out;
|
|
}
|
|
|
|
vma = find_vma(mm, address);
|
|
if (!vma) {
|
|
result = SCAN_VMA_NULL;
|
|
goto out;
|
|
}
|
|
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
|
|
hend = vma->vm_end & HPAGE_PMD_MASK;
|
|
if (address < hstart || address + HPAGE_PMD_SIZE > hend) {
|
|
result = SCAN_ADDRESS_RANGE;
|
|
goto out;
|
|
}
|
|
if (!hugepage_vma_check(vma)) {
|
|
result = SCAN_VMA_CHECK;
|
|
goto out;
|
|
}
|
|
pmd = mm_find_pmd(mm, address);
|
|
if (!pmd) {
|
|
result = SCAN_PMD_NULL;
|
|
goto out;
|
|
}
|
|
|
|
anon_vma_lock_write(vma->anon_vma);
|
|
|
|
pte = pte_offset_map(pmd, address);
|
|
pte_ptl = pte_lockptr(mm, pmd);
|
|
|
|
mmun_start = address;
|
|
mmun_end = address + HPAGE_PMD_SIZE;
|
|
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
|
|
pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
|
|
/*
|
|
* After this gup_fast can't run anymore. This also removes
|
|
* any huge TLB entry from the CPU so we won't allow
|
|
* huge and small TLB entries for the same virtual address
|
|
* to avoid the risk of CPU bugs in that area.
|
|
*/
|
|
_pmd = pmdp_collapse_flush(vma, address, pmd);
|
|
spin_unlock(pmd_ptl);
|
|
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
|
|
|
|
spin_lock(pte_ptl);
|
|
isolated = __collapse_huge_page_isolate(vma, address, pte);
|
|
spin_unlock(pte_ptl);
|
|
|
|
if (unlikely(!isolated)) {
|
|
pte_unmap(pte);
|
|
spin_lock(pmd_ptl);
|
|
BUG_ON(!pmd_none(*pmd));
|
|
/*
|
|
* We can only use set_pmd_at when establishing
|
|
* hugepmds and never for establishing regular pmds that
|
|
* points to regular pagetables. Use pmd_populate for that
|
|
*/
|
|
pmd_populate(mm, pmd, pmd_pgtable(_pmd));
|
|
spin_unlock(pmd_ptl);
|
|
anon_vma_unlock_write(vma->anon_vma);
|
|
result = SCAN_FAIL;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* All pages are isolated and locked so anon_vma rmap
|
|
* can't run anymore.
|
|
*/
|
|
anon_vma_unlock_write(vma->anon_vma);
|
|
|
|
__collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
|
|
pte_unmap(pte);
|
|
__SetPageUptodate(new_page);
|
|
pgtable = pmd_pgtable(_pmd);
|
|
|
|
_pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
|
|
_pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
|
|
|
|
/*
|
|
* spin_lock() below is not the equivalent of smp_wmb(), so
|
|
* this is needed to avoid the copy_huge_page writes to become
|
|
* visible after the set_pmd_at() write.
|
|
*/
|
|
smp_wmb();
|
|
|
|
spin_lock(pmd_ptl);
|
|
BUG_ON(!pmd_none(*pmd));
|
|
page_add_new_anon_rmap(new_page, vma, address, true);
|
|
mem_cgroup_commit_charge(new_page, memcg, false, true);
|
|
lru_cache_add_active_or_unevictable(new_page, vma);
|
|
pgtable_trans_huge_deposit(mm, pmd, pgtable);
|
|
set_pmd_at(mm, address, pmd, _pmd);
|
|
update_mmu_cache_pmd(vma, address, pmd);
|
|
spin_unlock(pmd_ptl);
|
|
|
|
*hpage = NULL;
|
|
|
|
khugepaged_pages_collapsed++;
|
|
result = SCAN_SUCCEED;
|
|
out_up_write:
|
|
up_write(&mm->mmap_sem);
|
|
trace_mm_collapse_huge_page(mm, isolated, result);
|
|
return;
|
|
|
|
out_nolock:
|
|
trace_mm_collapse_huge_page(mm, isolated, result);
|
|
return;
|
|
out:
|
|
mem_cgroup_cancel_charge(new_page, memcg, true);
|
|
goto out_up_write;
|
|
}
|
|
|
|
static int khugepaged_scan_pmd(struct mm_struct *mm,
|
|
struct vm_area_struct *vma,
|
|
unsigned long address,
|
|
struct page **hpage)
|
|
{
|
|
pmd_t *pmd;
|
|
pte_t *pte, *_pte;
|
|
int ret = 0, none_or_zero = 0, result = 0;
|
|
struct page *page = NULL;
|
|
unsigned long _address;
|
|
spinlock_t *ptl;
|
|
int node = NUMA_NO_NODE;
|
|
bool writable = false, referenced = false;
|
|
|
|
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
|
|
|
|
pmd = mm_find_pmd(mm, address);
|
|
if (!pmd) {
|
|
result = SCAN_PMD_NULL;
|
|
goto out;
|
|
}
|
|
|
|
memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
|
|
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
|
|
for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
|
|
_pte++, _address += PAGE_SIZE) {
|
|
pte_t pteval = *_pte;
|
|
if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
|
|
if (!userfaultfd_armed(vma) &&
|
|
++none_or_zero <= khugepaged_max_ptes_none) {
|
|
continue;
|
|
} else {
|
|
result = SCAN_EXCEED_NONE_PTE;
|
|
goto out_unmap;
|
|
}
|
|
}
|
|
if (!pte_present(pteval)) {
|
|
result = SCAN_PTE_NON_PRESENT;
|
|
goto out_unmap;
|
|
}
|
|
if (pte_write(pteval))
|
|
writable = true;
|
|
|
|
page = vm_normal_page(vma, _address, pteval);
|
|
if (unlikely(!page)) {
|
|
result = SCAN_PAGE_NULL;
|
|
goto out_unmap;
|
|
}
|
|
|
|
/* TODO: teach khugepaged to collapse THP mapped with pte */
|
|
if (PageCompound(page)) {
|
|
result = SCAN_PAGE_COMPOUND;
|
|
goto out_unmap;
|
|
}
|
|
|
|
/*
|
|
* Record which node the original page is from and save this
|
|
* information to khugepaged_node_load[].
|
|
* Khupaged will allocate hugepage from the node has the max
|
|
* hit record.
|
|
*/
|
|
node = page_to_nid(page);
|
|
if (khugepaged_scan_abort(node)) {
|
|
result = SCAN_SCAN_ABORT;
|
|
goto out_unmap;
|
|
}
|
|
khugepaged_node_load[node]++;
|
|
if (!PageLRU(page)) {
|
|
result = SCAN_PAGE_LRU;
|
|
goto out_unmap;
|
|
}
|
|
if (PageLocked(page)) {
|
|
result = SCAN_PAGE_LOCK;
|
|
goto out_unmap;
|
|
}
|
|
if (!PageAnon(page)) {
|
|
result = SCAN_PAGE_ANON;
|
|
goto out_unmap;
|
|
}
|
|
|
|
/*
|
|
* cannot use mapcount: can't collapse if there's a gup pin.
|
|
* The page must only be referenced by the scanned process
|
|
* and page swap cache.
|
|
*/
|
|
if (page_count(page) != 1 + !!PageSwapCache(page)) {
|
|
result = SCAN_PAGE_COUNT;
|
|
goto out_unmap;
|
|
}
|
|
if (pte_young(pteval) ||
|
|
page_is_young(page) || PageReferenced(page) ||
|
|
mmu_notifier_test_young(vma->vm_mm, address))
|
|
referenced = true;
|
|
}
|
|
if (writable) {
|
|
if (referenced) {
|
|
result = SCAN_SUCCEED;
|
|
ret = 1;
|
|
} else {
|
|
result = SCAN_NO_REFERENCED_PAGE;
|
|
}
|
|
} else {
|
|
result = SCAN_PAGE_RO;
|
|
}
|
|
out_unmap:
|
|
pte_unmap_unlock(pte, ptl);
|
|
if (ret) {
|
|
node = khugepaged_find_target_node();
|
|
/* collapse_huge_page will return with the mmap_sem released */
|
|
collapse_huge_page(mm, address, hpage, vma, node);
|
|
}
|
|
out:
|
|
trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
|
|
none_or_zero, result);
|
|
return ret;
|
|
}
|
|
|
|
static void collect_mm_slot(struct mm_slot *mm_slot)
|
|
{
|
|
struct mm_struct *mm = mm_slot->mm;
|
|
|
|
VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
|
|
|
|
if (khugepaged_test_exit(mm)) {
|
|
/* free mm_slot */
|
|
hash_del(&mm_slot->hash);
|
|
list_del(&mm_slot->mm_node);
|
|
|
|
/*
|
|
* Not strictly needed because the mm exited already.
|
|
*
|
|
* clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
|
|
*/
|
|
|
|
/* khugepaged_mm_lock actually not necessary for the below */
|
|
free_mm_slot(mm_slot);
|
|
mmdrop(mm);
|
|
}
|
|
}
|
|
|
|
static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
|
|
struct page **hpage)
|
|
__releases(&khugepaged_mm_lock)
|
|
__acquires(&khugepaged_mm_lock)
|
|
{
|
|
struct mm_slot *mm_slot;
|
|
struct mm_struct *mm;
|
|
struct vm_area_struct *vma;
|
|
int progress = 0;
|
|
|
|
VM_BUG_ON(!pages);
|
|
VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
|
|
|
|
if (khugepaged_scan.mm_slot)
|
|
mm_slot = khugepaged_scan.mm_slot;
|
|
else {
|
|
mm_slot = list_entry(khugepaged_scan.mm_head.next,
|
|
struct mm_slot, mm_node);
|
|
khugepaged_scan.address = 0;
|
|
khugepaged_scan.mm_slot = mm_slot;
|
|
}
|
|
spin_unlock(&khugepaged_mm_lock);
|
|
|
|
mm = mm_slot->mm;
|
|
down_read(&mm->mmap_sem);
|
|
if (unlikely(khugepaged_test_exit(mm)))
|
|
vma = NULL;
|
|
else
|
|
vma = find_vma(mm, khugepaged_scan.address);
|
|
|
|
progress++;
|
|
for (; vma; vma = vma->vm_next) {
|
|
unsigned long hstart, hend;
|
|
|
|
cond_resched();
|
|
if (unlikely(khugepaged_test_exit(mm))) {
|
|
progress++;
|
|
break;
|
|
}
|
|
if (!hugepage_vma_check(vma)) {
|
|
skip:
|
|
progress++;
|
|
continue;
|
|
}
|
|
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
|
|
hend = vma->vm_end & HPAGE_PMD_MASK;
|
|
if (hstart >= hend)
|
|
goto skip;
|
|
if (khugepaged_scan.address > hend)
|
|
goto skip;
|
|
if (khugepaged_scan.address < hstart)
|
|
khugepaged_scan.address = hstart;
|
|
VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
|
|
|
|
while (khugepaged_scan.address < hend) {
|
|
int ret;
|
|
cond_resched();
|
|
if (unlikely(khugepaged_test_exit(mm)))
|
|
goto breakouterloop;
|
|
|
|
VM_BUG_ON(khugepaged_scan.address < hstart ||
|
|
khugepaged_scan.address + HPAGE_PMD_SIZE >
|
|
hend);
|
|
ret = khugepaged_scan_pmd(mm, vma,
|
|
khugepaged_scan.address,
|
|
hpage);
|
|
/* move to next address */
|
|
khugepaged_scan.address += HPAGE_PMD_SIZE;
|
|
progress += HPAGE_PMD_NR;
|
|
if (ret)
|
|
/* we released mmap_sem so break loop */
|
|
goto breakouterloop_mmap_sem;
|
|
if (progress >= pages)
|
|
goto breakouterloop;
|
|
}
|
|
}
|
|
breakouterloop:
|
|
up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
|
|
breakouterloop_mmap_sem:
|
|
|
|
spin_lock(&khugepaged_mm_lock);
|
|
VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
|
|
/*
|
|
* Release the current mm_slot if this mm is about to die, or
|
|
* if we scanned all vmas of this mm.
|
|
*/
|
|
if (khugepaged_test_exit(mm) || !vma) {
|
|
/*
|
|
* Make sure that if mm_users is reaching zero while
|
|
* khugepaged runs here, khugepaged_exit will find
|
|
* mm_slot not pointing to the exiting mm.
|
|
*/
|
|
if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
|
|
khugepaged_scan.mm_slot = list_entry(
|
|
mm_slot->mm_node.next,
|
|
struct mm_slot, mm_node);
|
|
khugepaged_scan.address = 0;
|
|
} else {
|
|
khugepaged_scan.mm_slot = NULL;
|
|
khugepaged_full_scans++;
|
|
}
|
|
|
|
collect_mm_slot(mm_slot);
|
|
}
|
|
|
|
return progress;
|
|
}
|
|
|
|
static int khugepaged_has_work(void)
|
|
{
|
|
return !list_empty(&khugepaged_scan.mm_head) &&
|
|
khugepaged_enabled();
|
|
}
|
|
|
|
static int khugepaged_wait_event(void)
|
|
{
|
|
return !list_empty(&khugepaged_scan.mm_head) ||
|
|
kthread_should_stop();
|
|
}
|
|
|
|
static void khugepaged_do_scan(void)
|
|
{
|
|
struct page *hpage = NULL;
|
|
unsigned int progress = 0, pass_through_head = 0;
|
|
unsigned int pages = khugepaged_pages_to_scan;
|
|
bool wait = true;
|
|
|
|
barrier(); /* write khugepaged_pages_to_scan to local stack */
|
|
|
|
while (progress < pages) {
|
|
if (!khugepaged_prealloc_page(&hpage, &wait))
|
|
break;
|
|
|
|
cond_resched();
|
|
|
|
if (unlikely(kthread_should_stop() || try_to_freeze()))
|
|
break;
|
|
|
|
spin_lock(&khugepaged_mm_lock);
|
|
if (!khugepaged_scan.mm_slot)
|
|
pass_through_head++;
|
|
if (khugepaged_has_work() &&
|
|
pass_through_head < 2)
|
|
progress += khugepaged_scan_mm_slot(pages - progress,
|
|
&hpage);
|
|
else
|
|
progress = pages;
|
|
spin_unlock(&khugepaged_mm_lock);
|
|
}
|
|
|
|
if (!IS_ERR_OR_NULL(hpage))
|
|
put_page(hpage);
|
|
}
|
|
|
|
static void khugepaged_wait_work(void)
|
|
{
|
|
if (khugepaged_has_work()) {
|
|
if (!khugepaged_scan_sleep_millisecs)
|
|
return;
|
|
|
|
wait_event_freezable_timeout(khugepaged_wait,
|
|
kthread_should_stop(),
|
|
msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
|
|
return;
|
|
}
|
|
|
|
if (khugepaged_enabled())
|
|
wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
|
|
}
|
|
|
|
static int khugepaged(void *none)
|
|
{
|
|
struct mm_slot *mm_slot;
|
|
|
|
set_freezable();
|
|
set_user_nice(current, MAX_NICE);
|
|
|
|
while (!kthread_should_stop()) {
|
|
khugepaged_do_scan();
|
|
khugepaged_wait_work();
|
|
}
|
|
|
|
spin_lock(&khugepaged_mm_lock);
|
|
mm_slot = khugepaged_scan.mm_slot;
|
|
khugepaged_scan.mm_slot = NULL;
|
|
if (mm_slot)
|
|
collect_mm_slot(mm_slot);
|
|
spin_unlock(&khugepaged_mm_lock);
|
|
return 0;
|
|
}
|
|
|
|
static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
|
|
unsigned long haddr, pmd_t *pmd)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pgtable_t pgtable;
|
|
pmd_t _pmd;
|
|
int i;
|
|
|
|
/* leave pmd empty until pte is filled */
|
|
pmdp_huge_clear_flush_notify(vma, haddr, pmd);
|
|
|
|
pgtable = pgtable_trans_huge_withdraw(mm, pmd);
|
|
pmd_populate(mm, &_pmd, pgtable);
|
|
|
|
for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
|
|
pte_t *pte, entry;
|
|
entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
|
|
entry = pte_mkspecial(entry);
|
|
pte = pte_offset_map(&_pmd, haddr);
|
|
VM_BUG_ON(!pte_none(*pte));
|
|
set_pte_at(mm, haddr, pte, entry);
|
|
pte_unmap(pte);
|
|
}
|
|
smp_wmb(); /* make pte visible before pmd */
|
|
pmd_populate(mm, pmd, pgtable);
|
|
put_huge_zero_page();
|
|
}
|
|
|
|
static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long haddr, bool freeze)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page *page;
|
|
pgtable_t pgtable;
|
|
pmd_t _pmd;
|
|
bool young, write, dirty;
|
|
unsigned long addr;
|
|
int i;
|
|
|
|
VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
|
|
VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
|
|
VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
|
|
VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd));
|
|
|
|
count_vm_event(THP_SPLIT_PMD);
|
|
|
|
if (vma_is_dax(vma)) {
|
|
pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
|
|
if (is_huge_zero_pmd(_pmd))
|
|
put_huge_zero_page();
|
|
return;
|
|
} else if (is_huge_zero_pmd(*pmd)) {
|
|
return __split_huge_zero_page_pmd(vma, haddr, pmd);
|
|
}
|
|
|
|
page = pmd_page(*pmd);
|
|
VM_BUG_ON_PAGE(!page_count(page), page);
|
|
page_ref_add(page, HPAGE_PMD_NR - 1);
|
|
write = pmd_write(*pmd);
|
|
young = pmd_young(*pmd);
|
|
dirty = pmd_dirty(*pmd);
|
|
|
|
pmdp_huge_split_prepare(vma, haddr, pmd);
|
|
pgtable = pgtable_trans_huge_withdraw(mm, pmd);
|
|
pmd_populate(mm, &_pmd, pgtable);
|
|
|
|
for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
|
|
pte_t entry, *pte;
|
|
/*
|
|
* Note that NUMA hinting access restrictions are not
|
|
* transferred to avoid any possibility of altering
|
|
* permissions across VMAs.
|
|
*/
|
|
if (freeze) {
|
|
swp_entry_t swp_entry;
|
|
swp_entry = make_migration_entry(page + i, write);
|
|
entry = swp_entry_to_pte(swp_entry);
|
|
} else {
|
|
entry = mk_pte(page + i, vma->vm_page_prot);
|
|
entry = maybe_mkwrite(entry, vma);
|
|
if (!write)
|
|
entry = pte_wrprotect(entry);
|
|
if (!young)
|
|
entry = pte_mkold(entry);
|
|
}
|
|
if (dirty)
|
|
SetPageDirty(page + i);
|
|
pte = pte_offset_map(&_pmd, addr);
|
|
BUG_ON(!pte_none(*pte));
|
|
set_pte_at(mm, addr, pte, entry);
|
|
atomic_inc(&page[i]._mapcount);
|
|
pte_unmap(pte);
|
|
}
|
|
|
|
/*
|
|
* Set PG_double_map before dropping compound_mapcount to avoid
|
|
* false-negative page_mapped().
|
|
*/
|
|
if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
|
|
for (i = 0; i < HPAGE_PMD_NR; i++)
|
|
atomic_inc(&page[i]._mapcount);
|
|
}
|
|
|
|
if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
|
|
/* Last compound_mapcount is gone. */
|
|
__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
|
|
if (TestClearPageDoubleMap(page)) {
|
|
/* No need in mapcount reference anymore */
|
|
for (i = 0; i < HPAGE_PMD_NR; i++)
|
|
atomic_dec(&page[i]._mapcount);
|
|
}
|
|
}
|
|
|
|
smp_wmb(); /* make pte visible before pmd */
|
|
/*
|
|
* Up to this point the pmd is present and huge and userland has the
|
|
* whole access to the hugepage during the split (which happens in
|
|
* place). If we overwrite the pmd with the not-huge version pointing
|
|
* to the pte here (which of course we could if all CPUs were bug
|
|
* free), userland could trigger a small page size TLB miss on the
|
|
* small sized TLB while the hugepage TLB entry is still established in
|
|
* the huge TLB. Some CPU doesn't like that.
|
|
* See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
|
|
* 383 on page 93. Intel should be safe but is also warns that it's
|
|
* only safe if the permission and cache attributes of the two entries
|
|
* loaded in the two TLB is identical (which should be the case here).
|
|
* But it is generally safer to never allow small and huge TLB entries
|
|
* for the same virtual address to be loaded simultaneously. So instead
|
|
* of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
|
|
* current pmd notpresent (atomically because here the pmd_trans_huge
|
|
* and pmd_trans_splitting must remain set at all times on the pmd
|
|
* until the split is complete for this pmd), then we flush the SMP TLB
|
|
* and finally we write the non-huge version of the pmd entry with
|
|
* pmd_populate.
|
|
*/
|
|
pmdp_invalidate(vma, haddr, pmd);
|
|
pmd_populate(mm, pmd, pgtable);
|
|
|
|
if (freeze) {
|
|
for (i = 0; i < HPAGE_PMD_NR; i++) {
|
|
page_remove_rmap(page + i, false);
|
|
put_page(page + i);
|
|
}
|
|
}
|
|
}
|
|
|
|
void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long address, bool freeze)
|
|
{
|
|
spinlock_t *ptl;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long haddr = address & HPAGE_PMD_MASK;
|
|
|
|
mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
|
|
ptl = pmd_lock(mm, pmd);
|
|
if (pmd_trans_huge(*pmd)) {
|
|
struct page *page = pmd_page(*pmd);
|
|
if (PageMlocked(page))
|
|
clear_page_mlock(page);
|
|
} else if (!pmd_devmap(*pmd))
|
|
goto out;
|
|
__split_huge_pmd_locked(vma, pmd, haddr, freeze);
|
|
out:
|
|
spin_unlock(ptl);
|
|
mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
|
|
}
|
|
|
|
void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
|
|
bool freeze, struct page *page)
|
|
{
|
|
pgd_t *pgd;
|
|
pud_t *pud;
|
|
pmd_t *pmd;
|
|
|
|
pgd = pgd_offset(vma->vm_mm, address);
|
|
if (!pgd_present(*pgd))
|
|
return;
|
|
|
|
pud = pud_offset(pgd, address);
|
|
if (!pud_present(*pud))
|
|
return;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
if (!pmd_present(*pmd) || (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)))
|
|
return;
|
|
|
|
/*
|
|
* If caller asks to setup a migration entries, we need a page to check
|
|
* pmd against. Otherwise we can end up replacing wrong page.
|
|
*/
|
|
VM_BUG_ON(freeze && !page);
|
|
if (page && page != pmd_page(*pmd))
|
|
return;
|
|
|
|
/*
|
|
* Caller holds the mmap_sem write mode, so a huge pmd cannot
|
|
* materialize from under us.
|
|
*/
|
|
__split_huge_pmd(vma, pmd, address, freeze);
|
|
}
|
|
|
|
void vma_adjust_trans_huge(struct vm_area_struct *vma,
|
|
unsigned long start,
|
|
unsigned long end,
|
|
long adjust_next)
|
|
{
|
|
/*
|
|
* If the new start address isn't hpage aligned and it could
|
|
* previously contain an hugepage: check if we need to split
|
|
* an huge pmd.
|
|
*/
|
|
if (start & ~HPAGE_PMD_MASK &&
|
|
(start & HPAGE_PMD_MASK) >= vma->vm_start &&
|
|
(start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
|
|
split_huge_pmd_address(vma, start, false, NULL);
|
|
|
|
/*
|
|
* If the new end address isn't hpage aligned and it could
|
|
* previously contain an hugepage: check if we need to split
|
|
* an huge pmd.
|
|
*/
|
|
if (end & ~HPAGE_PMD_MASK &&
|
|
(end & HPAGE_PMD_MASK) >= vma->vm_start &&
|
|
(end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
|
|
split_huge_pmd_address(vma, end, false, NULL);
|
|
|
|
/*
|
|
* If we're also updating the vma->vm_next->vm_start, if the new
|
|
* vm_next->vm_start isn't page aligned and it could previously
|
|
* contain an hugepage: check if we need to split an huge pmd.
|
|
*/
|
|
if (adjust_next > 0) {
|
|
struct vm_area_struct *next = vma->vm_next;
|
|
unsigned long nstart = next->vm_start;
|
|
nstart += adjust_next << PAGE_SHIFT;
|
|
if (nstart & ~HPAGE_PMD_MASK &&
|
|
(nstart & HPAGE_PMD_MASK) >= next->vm_start &&
|
|
(nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
|
|
split_huge_pmd_address(next, nstart, false, NULL);
|
|
}
|
|
}
|
|
|
|
static void freeze_page(struct page *page)
|
|
{
|
|
enum ttu_flags ttu_flags = TTU_MIGRATION | TTU_IGNORE_MLOCK |
|
|
TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED;
|
|
int i, ret;
|
|
|
|
VM_BUG_ON_PAGE(!PageHead(page), page);
|
|
|
|
/* We only need TTU_SPLIT_HUGE_PMD once */
|
|
ret = try_to_unmap(page, ttu_flags | TTU_SPLIT_HUGE_PMD);
|
|
for (i = 1; !ret && i < HPAGE_PMD_NR; i++) {
|
|
/* Cut short if the page is unmapped */
|
|
if (page_count(page) == 1)
|
|
return;
|
|
|
|
ret = try_to_unmap(page + i, ttu_flags);
|
|
}
|
|
VM_BUG_ON(ret);
|
|
}
|
|
|
|
static void unfreeze_page(struct page *page)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < HPAGE_PMD_NR; i++)
|
|
remove_migration_ptes(page + i, page + i, true);
|
|
}
|
|
|
|
static void __split_huge_page_tail(struct page *head, int tail,
|
|
struct lruvec *lruvec, struct list_head *list)
|
|
{
|
|
struct page *page_tail = head + tail;
|
|
|
|
VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
|
|
VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
|
|
|
|
/*
|
|
* tail_page->_count is zero and not changing from under us. But
|
|
* get_page_unless_zero() may be running from under us on the
|
|
* tail_page. If we used atomic_set() below instead of atomic_inc(), we
|
|
* would then run atomic_set() concurrently with
|
|
* get_page_unless_zero(), and atomic_set() is implemented in C not
|
|
* using locked ops. spin_unlock on x86 sometime uses locked ops
|
|
* because of PPro errata 66, 92, so unless somebody can guarantee
|
|
* atomic_set() here would be safe on all archs (and not only on x86),
|
|
* it's safer to use atomic_inc().
|
|
*/
|
|
page_ref_inc(page_tail);
|
|
|
|
page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
|
|
page_tail->flags |= (head->flags &
|
|
((1L << PG_referenced) |
|
|
(1L << PG_swapbacked) |
|
|
(1L << PG_mlocked) |
|
|
(1L << PG_uptodate) |
|
|
(1L << PG_active) |
|
|
(1L << PG_locked) |
|
|
(1L << PG_unevictable) |
|
|
(1L << PG_dirty)));
|
|
|
|
/*
|
|
* After clearing PageTail the gup refcount can be released.
|
|
* Page flags also must be visible before we make the page non-compound.
|
|
*/
|
|
smp_wmb();
|
|
|
|
clear_compound_head(page_tail);
|
|
|
|
if (page_is_young(head))
|
|
set_page_young(page_tail);
|
|
if (page_is_idle(head))
|
|
set_page_idle(page_tail);
|
|
|
|
/* ->mapping in first tail page is compound_mapcount */
|
|
VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
|
|
page_tail);
|
|
page_tail->mapping = head->mapping;
|
|
|
|
page_tail->index = head->index + tail;
|
|
page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
|
|
lru_add_page_tail(head, page_tail, lruvec, list);
|
|
}
|
|
|
|
static void __split_huge_page(struct page *page, struct list_head *list)
|
|
{
|
|
struct page *head = compound_head(page);
|
|
struct zone *zone = page_zone(head);
|
|
struct lruvec *lruvec;
|
|
int i;
|
|
|
|
/* prevent PageLRU to go away from under us, and freeze lru stats */
|
|
spin_lock_irq(&zone->lru_lock);
|
|
lruvec = mem_cgroup_page_lruvec(head, zone);
|
|
|
|
/* complete memcg works before add pages to LRU */
|
|
mem_cgroup_split_huge_fixup(head);
|
|
|
|
for (i = HPAGE_PMD_NR - 1; i >= 1; i--)
|
|
__split_huge_page_tail(head, i, lruvec, list);
|
|
|
|
ClearPageCompound(head);
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
|
|
unfreeze_page(head);
|
|
|
|
for (i = 0; i < HPAGE_PMD_NR; i++) {
|
|
struct page *subpage = head + i;
|
|
if (subpage == page)
|
|
continue;
|
|
unlock_page(subpage);
|
|
|
|
/*
|
|
* Subpages may be freed if there wasn't any mapping
|
|
* like if add_to_swap() is running on a lru page that
|
|
* had its mapping zapped. And freeing these pages
|
|
* requires taking the lru_lock so we do the put_page
|
|
* of the tail pages after the split is complete.
|
|
*/
|
|
put_page(subpage);
|
|
}
|
|
}
|
|
|
|
int total_mapcount(struct page *page)
|
|
{
|
|
int i, ret;
|
|
|
|
VM_BUG_ON_PAGE(PageTail(page), page);
|
|
|
|
if (likely(!PageCompound(page)))
|
|
return atomic_read(&page->_mapcount) + 1;
|
|
|
|
ret = compound_mapcount(page);
|
|
if (PageHuge(page))
|
|
return ret;
|
|
for (i = 0; i < HPAGE_PMD_NR; i++)
|
|
ret += atomic_read(&page[i]._mapcount) + 1;
|
|
if (PageDoubleMap(page))
|
|
ret -= HPAGE_PMD_NR;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This calculates accurately how many mappings a transparent hugepage
|
|
* has (unlike page_mapcount() which isn't fully accurate). This full
|
|
* accuracy is primarily needed to know if copy-on-write faults can
|
|
* reuse the page and change the mapping to read-write instead of
|
|
* copying them. At the same time this returns the total_mapcount too.
|
|
*
|
|
* The function returns the highest mapcount any one of the subpages
|
|
* has. If the return value is one, even if different processes are
|
|
* mapping different subpages of the transparent hugepage, they can
|
|
* all reuse it, because each process is reusing a different subpage.
|
|
*
|
|
* The total_mapcount is instead counting all virtual mappings of the
|
|
* subpages. If the total_mapcount is equal to "one", it tells the
|
|
* caller all mappings belong to the same "mm" and in turn the
|
|
* anon_vma of the transparent hugepage can become the vma->anon_vma
|
|
* local one as no other process may be mapping any of the subpages.
|
|
*
|
|
* It would be more accurate to replace page_mapcount() with
|
|
* page_trans_huge_mapcount(), however we only use
|
|
* page_trans_huge_mapcount() in the copy-on-write faults where we
|
|
* need full accuracy to avoid breaking page pinning, because
|
|
* page_trans_huge_mapcount() is slower than page_mapcount().
|
|
*/
|
|
int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
|
|
{
|
|
int i, ret, _total_mapcount, mapcount;
|
|
|
|
/* hugetlbfs shouldn't call it */
|
|
VM_BUG_ON_PAGE(PageHuge(page), page);
|
|
|
|
if (likely(!PageTransCompound(page))) {
|
|
mapcount = atomic_read(&page->_mapcount) + 1;
|
|
if (total_mapcount)
|
|
*total_mapcount = mapcount;
|
|
return mapcount;
|
|
}
|
|
|
|
page = compound_head(page);
|
|
|
|
_total_mapcount = ret = 0;
|
|
for (i = 0; i < HPAGE_PMD_NR; i++) {
|
|
mapcount = atomic_read(&page[i]._mapcount) + 1;
|
|
ret = max(ret, mapcount);
|
|
_total_mapcount += mapcount;
|
|
}
|
|
if (PageDoubleMap(page)) {
|
|
ret -= 1;
|
|
_total_mapcount -= HPAGE_PMD_NR;
|
|
}
|
|
mapcount = compound_mapcount(page);
|
|
ret += mapcount;
|
|
_total_mapcount += mapcount;
|
|
if (total_mapcount)
|
|
*total_mapcount = _total_mapcount;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This function splits huge page into normal pages. @page can point to any
|
|
* subpage of huge page to split. Split doesn't change the position of @page.
|
|
*
|
|
* Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
|
|
* The huge page must be locked.
|
|
*
|
|
* If @list is null, tail pages will be added to LRU list, otherwise, to @list.
|
|
*
|
|
* Both head page and tail pages will inherit mapping, flags, and so on from
|
|
* the hugepage.
|
|
*
|
|
* GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
|
|
* they are not mapped.
|
|
*
|
|
* Returns 0 if the hugepage is split successfully.
|
|
* Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
|
|
* us.
|
|
*/
|
|
int split_huge_page_to_list(struct page *page, struct list_head *list)
|
|
{
|
|
struct page *head = compound_head(page);
|
|
struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
|
|
struct anon_vma *anon_vma;
|
|
int count, mapcount, ret;
|
|
bool mlocked;
|
|
unsigned long flags;
|
|
|
|
VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
|
|
VM_BUG_ON_PAGE(!PageAnon(page), page);
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
|
|
VM_BUG_ON_PAGE(!PageCompound(page), page);
|
|
|
|
/*
|
|
* The caller does not necessarily hold an mmap_sem that would prevent
|
|
* the anon_vma disappearing so we first we take a reference to it
|
|
* and then lock the anon_vma for write. This is similar to
|
|
* page_lock_anon_vma_read except the write lock is taken to serialise
|
|
* against parallel split or collapse operations.
|
|
*/
|
|
anon_vma = page_get_anon_vma(head);
|
|
if (!anon_vma) {
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
anon_vma_lock_write(anon_vma);
|
|
|
|
/*
|
|
* Racy check if we can split the page, before freeze_page() will
|
|
* split PMDs
|
|
*/
|
|
if (total_mapcount(head) != page_count(head) - 1) {
|
|
ret = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
mlocked = PageMlocked(page);
|
|
freeze_page(head);
|
|
VM_BUG_ON_PAGE(compound_mapcount(head), head);
|
|
|
|
/* Make sure the page is not on per-CPU pagevec as it takes pin */
|
|
if (mlocked)
|
|
lru_add_drain();
|
|
|
|
/* Prevent deferred_split_scan() touching ->_count */
|
|
spin_lock_irqsave(&pgdata->split_queue_lock, flags);
|
|
count = page_count(head);
|
|
mapcount = total_mapcount(head);
|
|
if (!mapcount && count == 1) {
|
|
if (!list_empty(page_deferred_list(head))) {
|
|
pgdata->split_queue_len--;
|
|
list_del(page_deferred_list(head));
|
|
}
|
|
spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
|
|
__split_huge_page(page, list);
|
|
ret = 0;
|
|
} else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
|
|
spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
|
|
pr_alert("total_mapcount: %u, page_count(): %u\n",
|
|
mapcount, count);
|
|
if (PageTail(page))
|
|
dump_page(head, NULL);
|
|
dump_page(page, "total_mapcount(head) > 0");
|
|
BUG();
|
|
} else {
|
|
spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
|
|
unfreeze_page(head);
|
|
ret = -EBUSY;
|
|
}
|
|
|
|
out_unlock:
|
|
anon_vma_unlock_write(anon_vma);
|
|
put_anon_vma(anon_vma);
|
|
out:
|
|
count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
|
|
return ret;
|
|
}
|
|
|
|
void free_transhuge_page(struct page *page)
|
|
{
|
|
struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&pgdata->split_queue_lock, flags);
|
|
if (!list_empty(page_deferred_list(page))) {
|
|
pgdata->split_queue_len--;
|
|
list_del(page_deferred_list(page));
|
|
}
|
|
spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
|
|
free_compound_page(page);
|
|
}
|
|
|
|
void deferred_split_huge_page(struct page *page)
|
|
{
|
|
struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
|
|
unsigned long flags;
|
|
|
|
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
|
|
|
|
spin_lock_irqsave(&pgdata->split_queue_lock, flags);
|
|
if (list_empty(page_deferred_list(page))) {
|
|
count_vm_event(THP_DEFERRED_SPLIT_PAGE);
|
|
list_add_tail(page_deferred_list(page), &pgdata->split_queue);
|
|
pgdata->split_queue_len++;
|
|
}
|
|
spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
|
|
}
|
|
|
|
static unsigned long deferred_split_count(struct shrinker *shrink,
|
|
struct shrink_control *sc)
|
|
{
|
|
struct pglist_data *pgdata = NODE_DATA(sc->nid);
|
|
return ACCESS_ONCE(pgdata->split_queue_len);
|
|
}
|
|
|
|
static unsigned long deferred_split_scan(struct shrinker *shrink,
|
|
struct shrink_control *sc)
|
|
{
|
|
struct pglist_data *pgdata = NODE_DATA(sc->nid);
|
|
unsigned long flags;
|
|
LIST_HEAD(list), *pos, *next;
|
|
struct page *page;
|
|
int split = 0;
|
|
|
|
spin_lock_irqsave(&pgdata->split_queue_lock, flags);
|
|
/* Take pin on all head pages to avoid freeing them under us */
|
|
list_for_each_safe(pos, next, &pgdata->split_queue) {
|
|
page = list_entry((void *)pos, struct page, mapping);
|
|
page = compound_head(page);
|
|
if (get_page_unless_zero(page)) {
|
|
list_move(page_deferred_list(page), &list);
|
|
} else {
|
|
/* We lost race with put_compound_page() */
|
|
list_del_init(page_deferred_list(page));
|
|
pgdata->split_queue_len--;
|
|
}
|
|
if (!--sc->nr_to_scan)
|
|
break;
|
|
}
|
|
spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
|
|
|
|
list_for_each_safe(pos, next, &list) {
|
|
page = list_entry((void *)pos, struct page, mapping);
|
|
lock_page(page);
|
|
/* split_huge_page() removes page from list on success */
|
|
if (!split_huge_page(page))
|
|
split++;
|
|
unlock_page(page);
|
|
put_page(page);
|
|
}
|
|
|
|
spin_lock_irqsave(&pgdata->split_queue_lock, flags);
|
|
list_splice_tail(&list, &pgdata->split_queue);
|
|
spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
|
|
|
|
/*
|
|
* Stop shrinker if we didn't split any page, but the queue is empty.
|
|
* This can happen if pages were freed under us.
|
|
*/
|
|
if (!split && list_empty(&pgdata->split_queue))
|
|
return SHRINK_STOP;
|
|
return split;
|
|
}
|
|
|
|
static struct shrinker deferred_split_shrinker = {
|
|
.count_objects = deferred_split_count,
|
|
.scan_objects = deferred_split_scan,
|
|
.seeks = DEFAULT_SEEKS,
|
|
.flags = SHRINKER_NUMA_AWARE,
|
|
};
|
|
|
|
#ifdef CONFIG_DEBUG_FS
|
|
static int split_huge_pages_set(void *data, u64 val)
|
|
{
|
|
struct zone *zone;
|
|
struct page *page;
|
|
unsigned long pfn, max_zone_pfn;
|
|
unsigned long total = 0, split = 0;
|
|
|
|
if (val != 1)
|
|
return -EINVAL;
|
|
|
|
for_each_populated_zone(zone) {
|
|
max_zone_pfn = zone_end_pfn(zone);
|
|
for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
|
|
if (!pfn_valid(pfn))
|
|
continue;
|
|
|
|
page = pfn_to_page(pfn);
|
|
if (!get_page_unless_zero(page))
|
|
continue;
|
|
|
|
if (zone != page_zone(page))
|
|
goto next;
|
|
|
|
if (!PageHead(page) || !PageAnon(page) ||
|
|
PageHuge(page))
|
|
goto next;
|
|
|
|
total++;
|
|
lock_page(page);
|
|
if (!split_huge_page(page))
|
|
split++;
|
|
unlock_page(page);
|
|
next:
|
|
put_page(page);
|
|
}
|
|
}
|
|
|
|
pr_info("%lu of %lu THP split\n", split, total);
|
|
|
|
return 0;
|
|
}
|
|
DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
|
|
"%llu\n");
|
|
|
|
static int __init split_huge_pages_debugfs(void)
|
|
{
|
|
void *ret;
|
|
|
|
ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
|
|
&split_huge_pages_fops);
|
|
if (!ret)
|
|
pr_warn("Failed to create split_huge_pages in debugfs");
|
|
return 0;
|
|
}
|
|
late_initcall(split_huge_pages_debugfs);
|
|
#endif
|