fe896d1878
The success of CMA allocation largely depends on the success of migration and key factor of it is page reference count. Until now, page reference is manipulated by direct calling atomic functions so we cannot follow up who and where manipulate it. Then, it is hard to find actual reason of CMA allocation failure. CMA allocation should be guaranteed to succeed so finding offending place is really important. In this patch, call sites where page reference is manipulated are converted to introduced wrapper function. This is preparation step to add tracepoint to each page reference manipulation function. With this facility, we can easily find reason of CMA allocation failure. There is no functional change in this patch. In addition, this patch also converts reference read sites. It will help a second step that renames page._count to something else and prevents later attempt to direct access to it (Suggested by Andrew). Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
152 lines
3.4 KiB
C
152 lines
3.4 KiB
C
/*
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* MMU context allocation for 64-bit kernels.
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*
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* Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/spinlock.h>
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#include <linux/idr.h>
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#include <linux/export.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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#include <asm/mmu_context.h>
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#include <asm/pgalloc.h>
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#include "icswx.h"
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static DEFINE_SPINLOCK(mmu_context_lock);
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static DEFINE_IDA(mmu_context_ida);
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int __init_new_context(void)
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{
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int index;
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int err;
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again:
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if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
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return -ENOMEM;
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spin_lock(&mmu_context_lock);
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err = ida_get_new_above(&mmu_context_ida, 1, &index);
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spin_unlock(&mmu_context_lock);
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if (err == -EAGAIN)
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goto again;
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else if (err)
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return err;
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if (index > MAX_USER_CONTEXT) {
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spin_lock(&mmu_context_lock);
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ida_remove(&mmu_context_ida, index);
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spin_unlock(&mmu_context_lock);
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return -ENOMEM;
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}
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return index;
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}
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EXPORT_SYMBOL_GPL(__init_new_context);
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int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
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{
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int index;
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index = __init_new_context();
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if (index < 0)
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return index;
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/* The old code would re-promote on fork, we don't do that
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* when using slices as it could cause problem promoting slices
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* that have been forced down to 4K
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*/
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if (slice_mm_new_context(mm))
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slice_set_user_psize(mm, mmu_virtual_psize);
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subpage_prot_init_new_context(mm);
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mm->context.id = index;
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#ifdef CONFIG_PPC_ICSWX
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mm->context.cop_lockp = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
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if (!mm->context.cop_lockp) {
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__destroy_context(index);
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subpage_prot_free(mm);
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mm->context.id = MMU_NO_CONTEXT;
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return -ENOMEM;
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}
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spin_lock_init(mm->context.cop_lockp);
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#endif /* CONFIG_PPC_ICSWX */
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#ifdef CONFIG_PPC_64K_PAGES
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mm->context.pte_frag = NULL;
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#endif
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#ifdef CONFIG_SPAPR_TCE_IOMMU
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mm_iommu_init(&mm->context);
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#endif
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return 0;
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}
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void __destroy_context(int context_id)
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{
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spin_lock(&mmu_context_lock);
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ida_remove(&mmu_context_ida, context_id);
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spin_unlock(&mmu_context_lock);
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}
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EXPORT_SYMBOL_GPL(__destroy_context);
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#ifdef CONFIG_PPC_64K_PAGES
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static void destroy_pagetable_page(struct mm_struct *mm)
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{
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int count;
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void *pte_frag;
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struct page *page;
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pte_frag = mm->context.pte_frag;
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if (!pte_frag)
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return;
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page = virt_to_page(pte_frag);
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/* drop all the pending references */
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count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
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/* We allow PTE_FRAG_NR fragments from a PTE page */
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if (page_ref_sub_and_test(page, PTE_FRAG_NR - count)) {
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pgtable_page_dtor(page);
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free_hot_cold_page(page, 0);
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}
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}
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#else
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static inline void destroy_pagetable_page(struct mm_struct *mm)
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{
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return;
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}
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#endif
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void destroy_context(struct mm_struct *mm)
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{
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#ifdef CONFIG_SPAPR_TCE_IOMMU
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mm_iommu_cleanup(&mm->context);
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#endif
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#ifdef CONFIG_PPC_ICSWX
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drop_cop(mm->context.acop, mm);
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kfree(mm->context.cop_lockp);
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mm->context.cop_lockp = NULL;
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#endif /* CONFIG_PPC_ICSWX */
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destroy_pagetable_page(mm);
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__destroy_context(mm->context.id);
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subpage_prot_free(mm);
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mm->context.id = MMU_NO_CONTEXT;
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}
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