* Replace the /sys/class/dax device model with /sys/bus/dax, and include
a compat driver so distributions can opt-in to the new ABI.
* Allow for an alternative driver for the device-dax address-range
* Introduce the 'kmem' driver to hotplug / assign a device-dax
address-range to the core-mm.
* Arrange for the device-dax target-node to be onlined so that the newly
added memory range can be uniquely referenced by numa apis.
-----BEGIN PGP SIGNATURE-----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=hfa3
-----END PGP SIGNATURE-----
Merge tag 'devdax-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull device-dax updates from Dan Williams:
"New device-dax infrastructure to allow persistent memory and other
"reserved" / performance differentiated memories, to be assigned to
the core-mm as "System RAM".
Some users want to use persistent memory as additional volatile
memory. They are willing to cope with potential performance
differences, for example between DRAM and 3D Xpoint, and want to use
typical Linux memory management apis rather than a userspace memory
allocator layered over an mmap() of a dax file. The administration
model is to decide how much Persistent Memory (pmem) to use as System
RAM, create a device-dax-mode namespace of that size, and then assign
it to the core-mm. The rationale for device-dax is that it is a
generic memory-mapping driver that can be layered over any "special
purpose" memory, not just pmem. On subsequent boots udev rules can be
used to restore the memory assignment.
One implication of using pmem as RAM is that mlock() no longer keeps
data off persistent media. For this reason it is recommended to enable
NVDIMM Security (previously merged for 5.0) to encrypt pmem contents
at rest. We considered making this recommendation an actively enforced
requirement, but in the end decided to leave it as a distribution /
administrator policy to allow for emulation and test environments that
lack security capable NVDIMMs.
Summary:
- Replace the /sys/class/dax device model with /sys/bus/dax, and
include a compat driver so distributions can opt-in to the new ABI.
- Allow for an alternative driver for the device-dax address-range
- Introduce the 'kmem' driver to hotplug / assign a device-dax
address-range to the core-mm.
- Arrange for the device-dax target-node to be onlined so that the
newly added memory range can be uniquely referenced by numa apis"
NOTE! I'm not entirely happy with the whole "PMEM as RAM" model because
we currently have special - and very annoying rules in the kernel about
accessing PMEM only with the "MC safe" accessors, because machine checks
inside the regular repeat string copy functions can be fatal in some
(not described) circumstances.
And apparently the PMEM modules can cause that a lot more than regular
RAM. The argument is that this happens because PMEM doesn't necessarily
get scrubbed at boot like RAM does, but that is planned to be added for
the user space tooling.
Quoting Dan from another email:
"The exposure can be reduced in the volatile-RAM case by scanning for
and clearing errors before it is onlined as RAM. The userspace tooling
for that can be in place before v5.1-final. There's also runtime
notifications of errors via acpi_nfit_uc_error_notify() from
background scrubbers on the DIMM devices. With that mechanism the
kernel could proactively clear newly discovered poison in the volatile
case, but that would be additional development more suitable for v5.2.
I understand the concern, and the need to highlight this issue by
tapping the brakes on feature development, but I don't see PMEM as RAM
making the situation worse when the exposure is also there via DAX in
the PMEM case. Volatile-RAM is arguably a safer use case since it's
possible to repair pages where the persistent case needs active
application coordination"
* tag 'devdax-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
device-dax: "Hotplug" persistent memory for use like normal RAM
mm/resource: Let walk_system_ram_range() search child resources
mm/memory-hotplug: Allow memory resources to be children
mm/resource: Move HMM pr_debug() deeper into resource code
mm/resource: Return real error codes from walk failures
device-dax: Add a 'modalias' attribute to DAX 'bus' devices
device-dax: Add a 'target_node' attribute
device-dax: Auto-bind device after successful new_id
acpi/nfit, device-dax: Identify differentiated memory with a unique numa-node
device-dax: Add /sys/class/dax backwards compatibility
device-dax: Add support for a dax override driver
device-dax: Move resource pinning+mapping into the common driver
device-dax: Introduce bus + driver model
device-dax: Start defining a dax bus model
device-dax: Remove multi-resource infrastructure
device-dax: Kill dax_region base
device-dax: Kill dax_region ida
-----BEGIN PGP SIGNATURE-----
iHUEABYIAB0WIQRTLbB6QfY48x44uB6AXGG7T9hjvgUCXIYrgwAKCRCAXGG7T9hj
viyuAP4/bKpQ8QUp2V6ddkyEG4NTkA7H87pqQQsxJe9sdoyRRwD5AReS7oitoRS/
cm6SBpwdaPRX/hfVvT2/h1GWxkvDFgA=
=8Zfa
-----END PGP SIGNATURE-----
Merge tag 'for-linus-5.1a-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen updates from Juergen Gross:
"xen fixes and features:
- remove fallback code for very old Xen hypervisors
- three patches for fixing Xen dom0 boot regressions
- an old patch for Xen PCI passthrough which was never applied for
unknown reasons
- some more minor fixes and cleanup patches"
* tag 'for-linus-5.1a-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: fix dom0 boot on huge systems
xen, cpu_hotplug: Prevent an out of bounds access
xen: remove pre-xen3 fallback handlers
xen/ACPI: Switch to bitmap_zalloc()
x86/xen: dont add memory above max allowed allocation
x86: respect memory size limiting via mem= parameter
xen/gntdev: Check and release imported dma-bufs on close
xen/gntdev: Do not destroy context while dma-bufs are in use
xen/pciback: Don't disable PCI_COMMAND on PCI device reset.
xen-scsiback: mark expected switch fall-through
xen: mark expected switch fall-through
When onlining a memory block with DEBUG_PAGEALLOC, it unmaps the pages
in the block from kernel, However, it does not map those pages while
offlining at the beginning. As the result, it triggers a panic below
while onlining on ppc64le as it checks if the pages are mapped before
unmapping. However, the imbalance exists for all arches where
double-unmappings could happen. Therefore, let kernel map those pages
in generic_online_page() before they have being freed into the page
allocator for the first time where it will set the page count to one.
On the other hand, it works fine during the boot, because at least for
IBM POWER8, it does,
early_setup
early_init_mmu
harsh__early_init_mmu
htab_initialize [1]
htab_bolt_mapping [2]
where it effectively map all memblock regions just like
kernel_map_linear_page(), so later mem_init() -> memblock_free_all()
will unmap them just fine without any imbalance. On other arches
without this imbalance checking, it still unmap them once at the most.
[1]
for_each_memblock(memory, reg) {
base = (unsigned long)__va(reg->base);
size = reg->size;
DBG("creating mapping for region: %lx..%lx (prot: %lx)\n",
base, size, prot);
BUG_ON(htab_bolt_mapping(base, base + size, __pa(base),
prot, mmu_linear_psize, mmu_kernel_ssize));
}
[2] linear_map_hash_slots[paddr >> PAGE_SHIFT] = ret | 0x80;
kernel BUG at arch/powerpc/mm/hash_utils_64.c:1815!
Oops: Exception in kernel mode, sig: 5 [#1]
LE SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA pSeries
CPU: 2 PID: 4298 Comm: bash Not tainted 5.0.0-rc7+ #15
NIP: c000000000062670 LR: c00000000006265c CTR: 0000000000000000
REGS: c0000005bf8a75b0 TRAP: 0700 Not tainted (5.0.0-rc7+)
MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 28422842
XER: 00000000
CFAR: c000000000804f44 IRQMASK: 1
NIP [c000000000062670] __kernel_map_pages+0x2e0/0x4f0
LR [c00000000006265c] __kernel_map_pages+0x2cc/0x4f0
Call Trace:
__kernel_map_pages+0x2cc/0x4f0
free_unref_page_prepare+0x2f0/0x4d0
free_unref_page+0x44/0x90
__online_page_free+0x84/0x110
online_pages_range+0xc0/0x150
walk_system_ram_range+0xc8/0x120
online_pages+0x280/0x5a0
memory_subsys_online+0x1b4/0x270
device_online+0xc0/0xf0
state_store+0xc0/0x180
dev_attr_store+0x3c/0x60
sysfs_kf_write+0x70/0xb0
kernfs_fop_write+0x10c/0x250
__vfs_write+0x48/0x240
vfs_write+0xd8/0x210
ksys_write+0x70/0x120
system_call+0x5c/0x70
Link: http://lkml.kernel.org/r/20190301220814.97339-1-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
isolate_huge_page() expects we pass the head of hugetlb page to it:
bool isolate_huge_page(...)
{
...
VM_BUG_ON_PAGE(!PageHead(page), page);
...
}
While I really cannot think of any situation where we end up with a
non-head page between hands in do_migrate_range(), let us make sure the
code is as sane as possible by explicitly passing the Head. Since we
already got the pointer, it does not take us extra effort.
Link: http://lkml.kernel.org/r/20190208090604.975-1-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the current implementation, there are two places to isolate a range
of page: __offline_pages() and alloc_contig_range(). During this
procedure, it will drain pages on pcp list.
Below is a brief call flow:
__offline_pages()/alloc_contig_range()
start_isolate_page_range()
set_migratetype_isolate()
drain_all_pages()
drain_all_pages() <--- A
This snippet shows the current logic is isolate and drain pcp list for
each pageblock and drain pcp list again for the whole range.
start_isolate_page_range is responsible for isolating the given pfn
range. One part of that job is to make sure that also pages that are on
the allocator pcp lists are properly isolated. Otherwise they could be
reused and the range wouldn't be completely isolated until the memory is
freed back. While there is no strict guarantee here because pages might
get allocated at any time before drain_all_pages is called there doesn't
seem to be any strong demand for such a guarantee.
In any case, draining is already done at the isolation level and there
is no need to do it again later by start_isolate_page_range callers
(memory hotplug and CMA allocator currently). Therefore remove
pointless draining in existing callers to make the code more clear and
functionally correct.
[mhocko@suse.com: provide a clearer changelog for the last two paragraphs]
Link: http://lkml.kernel.org/r/20190105233141.2329-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Replace all open encodings for NUMA_NO_NODE", v3.
All these places for replacement were found by running the following
grep patterns on the entire kernel code. Please let me know if this
might have missed some instances. This might also have replaced some
false positives. I will appreciate suggestions, inputs and review.
1. git grep "nid == -1"
2. git grep "node == -1"
3. git grep "nid = -1"
4. git grep "node = -1"
This patch (of 2):
At present there are multiple places where invalid node number is
encoded as -1. Even though implicitly understood it is always better to
have macros in there. Replace these open encodings for an invalid node
number with the global macro NUMA_NO_NODE. This helps remove NUMA
related assumptions like 'invalid node' from various places redirecting
them to a common definition.
Link: http://lkml.kernel.org/r/1545127933-10711-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> [ixgbe]
Acked-by: Jens Axboe <axboe@kernel.dk> [mtip32xx]
Acked-by: Vinod Koul <vkoul@kernel.org> [dmaengine.c]
Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Acked-by: Doug Ledford <dledford@redhat.com> [drivers/infiniband]
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When freeing pages are done with higher order, time spent on coalescing
pages by buddy allocator can be reduced. With section size of 256MB,
hot add latency of a single section shows improvement from 50-60 ms to
less than 1 ms, hence improving the hot add latency by 60 times. Modify
external providers of online callback to align with the change.
[arunks@codeaurora.org: v11]
Link: http://lkml.kernel.org/r/1547792588-18032-1-git-send-email-arunks@codeaurora.org
[akpm@linux-foundation.org: remove unused local, per Arun]
[akpm@linux-foundation.org: avoid return of void-returning __free_pages_core(), per Oscar]
[akpm@linux-foundation.org: fix it for mm-convert-totalram_pages-and-totalhigh_pages-variables-to-atomic.patch]
[arunks@codeaurora.org: v8]
Link: http://lkml.kernel.org/r/1547032395-24582-1-git-send-email-arunks@codeaurora.org
[arunks@codeaurora.org: v9]
Link: http://lkml.kernel.org/r/1547098543-26452-1-git-send-email-arunks@codeaurora.org
Link: http://lkml.kernel.org/r/1538727006-5727-1-git-send-email-arunks@codeaurora.org
Signed-off-by: Arun KS <arunks@codeaurora.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The mm/resource.c code is used to manage the physical address
space. The current resource configuration can be viewed in
/proc/iomem. An example of this is at the bottom of this
description.
The nvdimm subsystem "owns" the physical address resources which
map to persistent memory and has resources inserted for them as
"Persistent Memory". The best way to repurpose this for volatile
use is to leave the existing resource in place, but add a "System
RAM" resource underneath it. This clearly communicates the
ownership relationship of this memory.
The request_resource_conflict() API only deals with the
top-level resources. Replace it with __request_region() which
will search for !IORESOURCE_BUSY areas lower in the resource
tree than the top level.
We *could* also simply truncate the existing top-level
"Persistent Memory" resource and take over the released address
space. But, this means that if we ever decide to hot-unplug the
"RAM" and give it back, we need to recreate the original setup,
which may mean going back to the BIOS tables.
This should have no real effect on the existing collision
detection because the areas that truly conflict should be marked
IORESOURCE_BUSY.
00000000-00000fff : Reserved
00001000-0009fbff : System RAM
0009fc00-0009ffff : Reserved
000a0000-000bffff : PCI Bus 0000:00
000c0000-000c97ff : Video ROM
000c9800-000ca5ff : Adapter ROM
000f0000-000fffff : Reserved
000f0000-000fffff : System ROM
00100000-9fffffff : System RAM
01000000-01e071d0 : Kernel code
01e071d1-027dfdff : Kernel data
02dc6000-0305dfff : Kernel bss
a0000000-afffffff : Persistent Memory (legacy)
a0000000-a7ffffff : System RAM
b0000000-bffdffff : System RAM
bffe0000-bfffffff : Reserved
c0000000-febfffff : PCI Bus 0000:00
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: Huang Ying <ying.huang@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Keith Busch <keith.busch@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
HMM consumes physical address space for its own use, even
though nothing is mapped or accessible there. It uses a
special resource description (IORES_DESC_DEVICE_PRIVATE_MEMORY)
to uniquely identify these areas.
When HMM consumes address space, it makes a best guess about
what to consume. However, it is possible that a future memory
or device hotplug can collide with the reserved area. In the
case of these conflicts, there is an error message in
register_memory_resource().
Later patches in this series move register_memory_resource()
from using request_resource_conflict() to __request_region().
Unfortunately, __request_region() does not return the conflict
like the previous function did, which makes it impossible to
check for IORES_DESC_DEVICE_PRIVATE_MEMORY in a conflicting
resource.
Instead of warning in register_memory_resource(), move the
check into the core resource code itself (__request_region())
where the conflicting resource _is_ available. This has the
added bonus of producing a warning in case of HMM conflicts
with devices *or* RAM address space, as opposed to the RAM-
only warnings that were there previously.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: Huang Ying <ying.huang@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Rong Chen has reported the following boot crash:
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 1 PID: 239 Comm: udevd Not tainted 5.0.0-rc4-00149-gefad4e4 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
RIP: 0010:page_mapping+0x12/0x80
Code: 5d c3 48 89 df e8 0e ad 02 00 85 c0 75 da 89 e8 5b 5d c3 0f 1f 44 00 00 53 48 89 fb 48 8b 43 08 48 8d 50 ff a8 01 48 0f 45 da <48> 8b 53 08 48 8d 42 ff 83 e2 01 48 0f 44 c3 48 83 38 ff 74 2f 48
RSP: 0018:ffff88801fa87cd8 EFLAGS: 00010202
RAX: ffffffffffffffff RBX: fffffffffffffffe RCX: 000000000000000a
RDX: fffffffffffffffe RSI: ffffffff820b9a20 RDI: ffff88801e5c0000
RBP: 6db6db6db6db6db7 R08: ffff88801e8bb000 R09: 0000000001b64d13
R10: ffff88801fa87cf8 R11: 0000000000000001 R12: ffff88801e640000
R13: ffffffff820b9a20 R14: ffff88801f145258 R15: 0000000000000001
FS: 00007fb2079817c0(0000) GS:ffff88801dd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000006 CR3: 000000001fa82000 CR4: 00000000000006a0
Call Trace:
__dump_page+0x14/0x2c0
is_mem_section_removable+0x24c/0x2c0
removable_show+0x87/0xa0
dev_attr_show+0x25/0x60
sysfs_kf_seq_show+0xba/0x110
seq_read+0x196/0x3f0
__vfs_read+0x34/0x180
vfs_read+0xa0/0x150
ksys_read+0x44/0xb0
do_syscall_64+0x5e/0x4a0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
and bisected it down to commit efad4e475c ("mm, memory_hotplug:
is_mem_section_removable do not pass the end of a zone").
The reason for the crash is that the mapping is garbage for poisoned
(uninitialized) page. This shouldn't happen as all pages in the zone's
boundary should be initialized.
Later debugging revealed that the actual problem is an off-by-one when
evaluating the end_page. 'start_pfn + nr_pages' resp 'zone_end_pfn'
refers to a pfn after the range and as such it might belong to a
differen memory section.
This along with CONFIG_SPARSEMEM then makes the loop condition
completely bogus because a pointer arithmetic doesn't work for pages
from two different sections in that memory model.
Fix the issue by reworking is_pageblock_removable to be pfn based and
only use struct page where necessary. This makes the code slightly
easier to follow and we will remove the problematic pointer arithmetic
completely.
Link: http://lkml.kernel.org/r/20190218181544.14616-1-mhocko@kernel.org
Fixes: efad4e475c ("mm, memory_hotplug: is_mem_section_removable do not pass the end of a zone")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: <rong.a.chen@intel.com>
Tested-by: <rong.a.chen@intel.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When limiting memory size via kernel parameter "mem=" this should be
respected even in case of memory made accessible via a PCI card.
Today this kind of memory won't be made usable in initial memory
setup as the memory won't be visible in E820 map, but it might be
added when adding PCI devices due to corresponding ACPI table entries.
Not respecting "mem=" can be corrected by adding a global max_mem_size
variable set by parse_memopt() which will result in rejecting adding
memory areas resulting in a memory size above the allowed limit.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Jan has noticed that we do double unlock on some failure paths when
offlining a page range. This is indeed the case when
test_pages_in_a_zone respp. start_isolate_page_range fail. This was an
omission when forward porting the debugging patch from an older kernel.
Fix the issue by dropping mem_hotplug_done from the failure condition
and keeping the single unlock in the catch all failure path.
Link: http://lkml.kernel.org/r/20190115120307.22768-1-mhocko@kernel.org
Fixes: 7960509329 ("mm, memory_hotplug: print reason for the offlining failure")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the same sort of error we saw in commit 17e2e7d7e1 ("mm,
page_alloc: fix has_unmovable_pages for HugePages").
Gigantic hugepages cross several memblocks, so it can be that the page
we get in scan_movable_pages() is a page-tail belonging to a
1G-hugepage. If that happens, page_hstate()->size_to_hstate() will
return NULL, and we will blow up in hugepage_migration_supported().
The splat is as follows:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
#PF error: [normal kernel read fault]
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 1 PID: 1350 Comm: bash Tainted: G E 5.0.0-rc1-mm1-1-default+ #27
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
RIP: 0010:__offline_pages+0x6ae/0x900
Call Trace:
memory_subsys_offline+0x42/0x60
device_offline+0x80/0xa0
state_store+0xab/0xc0
kernfs_fop_write+0x102/0x180
__vfs_write+0x26/0x190
vfs_write+0xad/0x1b0
ksys_write+0x42/0x90
do_syscall_64+0x5b/0x180
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Modules linked in: af_packet(E) xt_tcpudp(E) ipt_REJECT(E) xt_conntrack(E) nf_conntrack(E) nf_defrag_ipv4(E) ip_set(E) nfnetlink(E) ebtable_nat(E) ebtable_broute(E) bridge(E) stp(E) llc(E) iptable_mangle(E) iptable_raw(E) iptable_security(E) ebtable_filter(E) ebtables(E) iptable_filter(E) ip_tables(E) x_tables(E) kvm_intel(E) kvm(E) irqbypass(E) crct10dif_pclmul(E) crc32_pclmul(E) ghash_clmulni_intel(E) bochs_drm(E) ttm(E) aesni_intel(E) drm_kms_helper(E) aes_x86_64(E) crypto_simd(E) cryptd(E) glue_helper(E) drm(E) virtio_net(E) syscopyarea(E) sysfillrect(E) net_failover(E) sysimgblt(E) pcspkr(E) failover(E) i2c_piix4(E) fb_sys_fops(E) parport_pc(E) parport(E) button(E) btrfs(E) libcrc32c(E) xor(E) zstd_decompress(E) zstd_compress(E) xxhash(E) raid6_pq(E) sd_mod(E) ata_generic(E) ata_piix(E) ahci(E) libahci(E) libata(E) crc32c_intel(E) serio_raw(E) virtio_pci(E) virtio_ring(E) virtio(E) sg(E) scsi_mod(E) autofs4(E)
[akpm@linux-foundation.org: fix brace layout, per David. Reduce indentation]
Link: http://lkml.kernel.org/r/20190122154407.18417-1-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If memory end is not aligned with the sparse memory section boundary,
the mapping of such a section is only partly initialized. This may lead
to VM_BUG_ON due to uninitialized struct pages access from
test_pages_in_a_zone() function triggered by memory_hotplug sysfs
handlers.
Here are the the panic examples:
CONFIG_DEBUG_VM_PGFLAGS=y
kernel parameter mem=2050M
--------------------------
page:000003d082008000 is uninitialized and poisoned
page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
Call Trace:
test_pages_in_a_zone+0xde/0x160
show_valid_zones+0x5c/0x190
dev_attr_show+0x34/0x70
sysfs_kf_seq_show+0xc8/0x148
seq_read+0x204/0x480
__vfs_read+0x32/0x178
vfs_read+0x82/0x138
ksys_read+0x5a/0xb0
system_call+0xdc/0x2d8
Last Breaking-Event-Address:
test_pages_in_a_zone+0xde/0x160
Kernel panic - not syncing: Fatal exception: panic_on_oops
Fix this by checking whether the pfn to check is within the zone.
[mhocko@suse.com: separated this change from http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com]
Link: http://lkml.kernel.org/r/20190128144506.15603-3-mhocko@kernel.org
[mhocko@suse.com: separated this change from
http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com]
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm, memory_hotplug: fix uninitialized pages fallouts", v2.
Mikhail Zaslonko has posted fixes for the two bugs quite some time ago
[1]. I have pushed back on those fixes because I believed that it is
much better to plug the problem at the initialization time rather than
play whack-a-mole all over the hotplug code and find all the places
which expect the full memory section to be initialized.
We have ended up with commit 2830bf6f05 ("mm, memory_hotplug:
initialize struct pages for the full memory section") merged and cause a
regression [2][3]. The reason is that there might be memory layouts
when two NUMA nodes share the same memory section so the merged fix is
simply incorrect.
In order to plug this hole we really have to be zone range aware in
those handlers. I have split up the original patch into two. One is
unchanged (patch 2) and I took a different approach for `removable'
crash.
[1] http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1666948
[3] http://lkml.kernel.org/r/20190125163938.GA20411@dhcp22.suse.cz
This patch (of 2):
Mikhail has reported the following VM_BUG_ON triggered when reading sysfs
removable state of a memory block:
page:000003d08300c000 is uninitialized and poisoned
page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
Call Trace:
is_mem_section_removable+0xb4/0x190
show_mem_removable+0x9a/0xd8
dev_attr_show+0x34/0x70
sysfs_kf_seq_show+0xc8/0x148
seq_read+0x204/0x480
__vfs_read+0x32/0x178
vfs_read+0x82/0x138
ksys_read+0x5a/0xb0
system_call+0xdc/0x2d8
Last Breaking-Event-Address:
is_mem_section_removable+0xb4/0x190
Kernel panic - not syncing: Fatal exception: panic_on_oops
The reason is that the memory block spans the zone boundary and we are
stumbling over an unitialized struct page. Fix this by enforcing zone
range in is_mem_section_removable so that we never run away from a zone.
Link: http://lkml.kernel.org/r/20190128144506.15603-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Debugged-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_migrate_range() takes a memory range and tries to isolate the pages
to put them into a list. This list will be later on used in
migrate_pages() to know the pages we need to migrate.
Currently, if we fail to isolate a single page, we put all already
isolated pages back to their LRU and we bail out from the function.
This is quite suboptimal, as this will force us to start over again
because scan_movable_pages will give us the same range. If there is no
chance that we can isolate that page, we will loop here forever.
Issue debugged in [1] has proved that. During the debugging of that
issue, it was noticed that if do_migrate_ranges() fails to isolate a
single page, we will just discard the work we have done so far and bail
out, which means that scan_movable_pages() will find again the same set
of pages.
Instead, we can just skip the error, keep isolating as much pages as
possible and then proceed with the call to migrate_pages().
This will allow us to do as much work as possible at once.
[1] https://lkml.org/lkml/2018/12/6/324
Michal said:
: I still think that this doesn't give us a whole picture. Looping for
: ever is a bug. Failing the isolation is quite possible and it should
: be a ephemeral condition (e.g. a race with freeing the page or
: somebody else isolating the page for whatever reason). And here comes
: the disadvantage of the current implementation. We simply throw
: everything on the floor just because of a ephemeral condition. The
: racy page_count check is quite dubious to prevent from that.
Link: http://lkml.kernel.org/r/20181211135312.27034-1-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Memory migration might fail during offlining and we keep retrying in that
case. This is currently obfuscated by goto retry loop. The code is hard
to follow and as a result it is even suboptimal becase each retry round
scans the full range from start_pfn even though we have successfully
scanned/migrated [start_pfn, pfn] range already. This is all only because
check_pages_isolated failure has to rescan the full range again.
De-obfuscate the migration retry loop by promoting it to a real for loop.
In fact remove the goto altogether by making it a proper double loop
(yeah, gotos are nasty in this specific case). In the end we will get a
slightly more optimal code which is better readable.
[akpm@linux-foundation.org: reflow comments to 80 cols]
Link: http://lkml.kernel.org/r/20181211142741.2607-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "few memory offlining enhancements".
I have been chasing memory offlining not making progress recently. On the
way I have noticed few weird decisions in the code. The migration itself
is restricted without a reasonable justification and the retry loop around
the migration is quite messy. This is addressed by patch 1 and patch 2.
Patch 3 is targeting on the faultaround code which has been a hot
candidate for the initial issue reported upstream [2] and that I am
debugging internally. It turned out to be not the main contributor in the
end but I believe we should address it regardless. See the patch
description for more details.
[1] http://lkml.kernel.org/r/20181120134323.13007-1-mhocko@kernel.org
[2] http://lkml.kernel.org/r/20181114070909.GB2653@MiWiFi-R3L-srv
This patch (of 3):
do_migrate_range has been limiting the number of pages to migrate to 256
for some reason which is not documented. Even if the limit made some
sense back then when it was introduced it doesn't really serve a good
purpose these days. If the range contains huge pages then we break out of
the loop too early and go through LRU and pcp caches draining and
scan_movable_pages is quite suboptimal.
The only reason to limit the number of pages I can think of is to reduce
the potential time to react on the fatal signal. But even then the number
of pages is a questionable metric because even a single page migration
might block in a non-killable state (e.g. __unmap_and_move).
Remove the limit and offline the full requested range (this is one
memblock worth of pages with the current code). Should we ever get a
report that offlining takes too long to react on fatal signal then we
should rather fix the core migration to use killable waits and bailout
on a signal.
Link: http://lkml.kernel.org/r/20181211142741.2607-1-mhocko@kernel.org
Link: http://lkml.kernel.org/r/20181211142741.2607-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have received a bug report that an injected MCE about faulty memory
prevents memory offline to succeed on 4.4 base kernel. The underlying
reason was that the HWPoison page has an elevated reference count and the
migration keeps failing. There are two problems with that. First of all
it is dubious to migrate the poisoned page because we know that accessing
that memory is possible to fail. Secondly it doesn't make any sense to
migrate a potentially broken content and preserve the memory corruption
over to a new location.
Oscar has found out that 4.4 and the current upstream kernels behave
slightly differently with his simply testcase
===
int main(void)
{
int ret;
int i;
int fd;
char *array = malloc(4096);
char *array_locked = malloc(4096);
fd = open("/tmp/data", O_RDONLY);
read(fd, array, 4095);
for (i = 0; i < 4096; i++)
array_locked[i] = 'd';
ret = mlock((void *)PAGE_ALIGN((unsigned long)array_locked), sizeof(array_locked));
if (ret)
perror("mlock");
sleep (20);
ret = madvise((void *)PAGE_ALIGN((unsigned long)array_locked), 4096, MADV_HWPOISON);
if (ret)
perror("madvise");
for (i = 0; i < 4096; i++)
array_locked[i] = 'd';
return 0;
}
===
+ offline this memory.
In 4.4 kernels he saw the hwpoisoned page to be returned back to the LRU
list
kernel: [<ffffffff81019ac9>] dump_trace+0x59/0x340
kernel: [<ffffffff81019e9a>] show_stack_log_lvl+0xea/0x170
kernel: [<ffffffff8101ac71>] show_stack+0x21/0x40
kernel: [<ffffffff8132bb90>] dump_stack+0x5c/0x7c
kernel: [<ffffffff810815a1>] warn_slowpath_common+0x81/0xb0
kernel: [<ffffffff811a275c>] __pagevec_lru_add_fn+0x14c/0x160
kernel: [<ffffffff811a2eed>] pagevec_lru_move_fn+0xad/0x100
kernel: [<ffffffff811a334c>] __lru_cache_add+0x6c/0xb0
kernel: [<ffffffff81195236>] add_to_page_cache_lru+0x46/0x70
kernel: [<ffffffffa02b4373>] extent_readpages+0xc3/0x1a0 [btrfs]
kernel: [<ffffffff811a16d7>] __do_page_cache_readahead+0x177/0x200
kernel: [<ffffffff811a18c8>] ondemand_readahead+0x168/0x2a0
kernel: [<ffffffff8119673f>] generic_file_read_iter+0x41f/0x660
kernel: [<ffffffff8120e50d>] __vfs_read+0xcd/0x140
kernel: [<ffffffff8120e9ea>] vfs_read+0x7a/0x120
kernel: [<ffffffff8121404b>] kernel_read+0x3b/0x50
kernel: [<ffffffff81215c80>] do_execveat_common.isra.29+0x490/0x6f0
kernel: [<ffffffff81215f08>] do_execve+0x28/0x30
kernel: [<ffffffff81095ddb>] call_usermodehelper_exec_async+0xfb/0x130
kernel: [<ffffffff8161c045>] ret_from_fork+0x55/0x80
And that latter confuses the hotremove path because an LRU page is
attempted to be migrated and that fails due to an elevated reference
count. It is quite possible that the reuse of the HWPoisoned page is some
kind of fixed race condition but I am not really sure about that.
With the upstream kernel the failure is slightly different. The page
doesn't seem to have LRU bit set but isolate_movable_page simply fails and
do_migrate_range simply puts all the isolated pages back to LRU and
therefore no progress is made and scan_movable_pages finds same set of
pages over and over again.
Fix both cases by explicitly checking HWPoisoned pages before we even try
to get reference on the page, try to unmap it if it is still mapped. As
explained by Naoya:
: Hwpoison code never unmapped those for no big reason because
: Ksm pages never dominate memory, so we simply didn't have strong
: motivation to save the pages.
Also put WARN_ON(PageLRU) in case there is a race and we can hit LRU
HWPoison pages which shouldn't happen but I couldn't convince myself about
that. Naoya has noted the following:
: Theoretically no such gurantee, because try_to_unmap() doesn't have a
: guarantee of success and then memory_failure() returns immediately
: when hwpoison_user_mappings fails.
: Or the following code (comes after hwpoison_user_mappings block) also impli=
: es
: that the target page can still have PageLRU flag.
:
: /*
: * Torn down by someone else?
: */
: if (PageLRU(p) && !PageSwapCache(p) && p->mapping =3D=3D NULL) {
: action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
: res =3D -EBUSY;
: goto out;
: }
:
: So I think it's OK to keep "if (WARN_ON(PageLRU(page)))" block in
: current version of your patch.
Link: http://lkml.kernel.org/r/20181206120135.14079-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.com>
Debugged-by: Oscar Salvador <osalvador@suse.com>
Tested-by: Oscar Salvador <osalvador@suse.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During online_pages phase, pgdat->nr_zones will be updated in case this
zone is empty.
Currently the online_pages phase is protected by the global locks
(device_device_hotplug_lock and mem_hotplug_lock), which ensures there is
no contention during the update of nr_zones.
These global locks introduces scalability issues (especially the second
one), which slow down code relying on get_online_mems(). This is also a
preparation for not having to rely on get_online_mems() but instead some
more fine grained locks.
The patch moves init_currently_empty_zone under both zone_span_writelock
and pgdat_resize_lock because both the pgdat state is changed (nr_zones)
and the zone's start_pfn. Also this patch changes the documentation of
node_size_lock to include the protection of nr_zones.
Link: http://lkml.kernel.org/r/20181203205016.14123-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since the information needed in sparse_add_one_section() is node id to
allocate proper memory, it is not necessary to pass its pgdat.
This patch changes the prototype of sparse_add_one_section() to pass node
id directly. This is intended to reduce misleading that
sparse_add_one_section() would touch pgdat.
Link: http://lkml.kernel.org/r/20181204085657.20472-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Do not touch pages in hot-remove path", v2.
This patchset aims for two things:
1) A better definition about offline and hot-remove stage
2) Solving bugs where we can access non-initialized pages
during hot-remove operations [2] [3].
This is achieved by moving all page/zone handling to the offline
stage, so we do not need to access pages when hot-removing memory.
[1] https://patchwork.kernel.org/cover/10691415/
[2] https://patchwork.kernel.org/patch/10547445/
[3] https://www.spinics.net/lists/linux-mm/msg161316.html
This patch (of 5):
This is a preparation for the following-up patches. The idea of passing
the nid is that it will allow us to get rid of the zone parameter
afterwards.
Link: http://lkml.kernel.org/r/20181127162005.15833-2-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Userspace should always be in charge of how to online memory and if memory
should be onlined automatically in the kernel. Let's drop the parameter
to overwrite this - XEN passes memhp_auto_online, just like add_memory(),
so we can directly use that instead internally.
Link: http://lkml.kernel.org/r/20181123123740.27652-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Per-cpu numa_node provides a default node for each possible cpu. The
association gets initialized during the boot when the architecture
specific code explores cpu->NUMA affinity. When the whole NUMA node is
removed though we are clearing this association
try_offline_node
check_and_unmap_cpu_on_node
unmap_cpu_on_node
numa_clear_node
numa_set_node(cpu, NUMA_NO_NODE)
This means that whoever calls cpu_to_node for a cpu associated with such a
node will get NUMA_NO_NODE. This is problematic for two reasons. First
it is fragile because __alloc_pages_node would simply blow up on an
out-of-bound access. We have encountered this when loading kvm module
BUG: unable to handle kernel paging request at 00000000000021c0
IP: __alloc_pages_nodemask+0x93/0xb70
PGD 800000ffe853e067 PUD 7336bbc067 PMD 0
Oops: 0000 [#1] SMP
[...]
CPU: 88 PID: 1223749 Comm: modprobe Tainted: G W 4.4.156-94.64-default #1
RIP: __alloc_pages_nodemask+0x93/0xb70
RSP: 0018:ffff887354493b40 EFLAGS: 00010202
RAX: 00000000000021c0 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00000000014000c0
RBP: 00000000014000c0 R08: ffffffffffffffff R09: 0000000000000000
R10: ffff88fffc89e790 R11: 0000000000014000 R12: 0000000000000101
R13: ffffffffa0772cd4 R14: ffffffffa0769ac0 R15: 0000000000000000
FS: 00007fdf2f2f1700(0000) GS:ffff88fffc880000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000021c0 CR3: 00000077205ee000 CR4: 0000000000360670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
alloc_vmcs_cpu+0x3d/0x90 [kvm_intel]
hardware_setup+0x781/0x849 [kvm_intel]
kvm_arch_hardware_setup+0x28/0x190 [kvm]
kvm_init+0x7c/0x2d0 [kvm]
vmx_init+0x1e/0x32c [kvm_intel]
do_one_initcall+0xca/0x1f0
do_init_module+0x5a/0x1d7
load_module+0x1393/0x1c90
SYSC_finit_module+0x70/0xa0
entry_SYSCALL_64_fastpath+0x1e/0xb7
DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x1e/0xb7
on an older kernel but the code is basically the same in the current Linus
tree as well. alloc_vmcs_cpu could use alloc_pages_nodemask which would
recognize NUMA_NO_NODE and use alloc_pages_node which would translate it
to numa_mem_id but that is wrong as well because it would use a cpu
affinity of the local CPU which might be quite far from the original node.
It is also reasonable to expect that cpu_to_node will provide a sane
value and there might be many more callers like that.
The second problem is that __register_one_node relies on cpu_to_node to
properly associate cpus back to the node when it is onlined. We do not
want to lose that link as there is no arch independent way to get it from
the early boot time AFAICS.
Drop the whole check_and_unmap_cpu_on_node machinery and keep the
association to fix both issues. The NODE_DATA(nid) is not deallocated so
it will stay in place and if anybody wants to allocate from that node then
a fallback node will be used.
Thanks to Vlastimil Babka for his live system debugging skills that helped
debugging the issue.
Link: http://lkml.kernel.org/r/20181108100413.966-1-mhocko@kernel.org
Fixes: e13fe8695c ("cpu-hotplug,memory-hotplug: clear cpu_to_node() when offlining the node")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Debugged-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Heiko has complained that his log is swamped by warnings from
has_unmovable_pages
[ 20.536664] page dumped because: has_unmovable_pages
[ 20.536792] page:000003d081ff4080 count:1 mapcount:0 mapping:000000008ff88600 index:0x0 compound_mapcount: 0
[ 20.536794] flags: 0x3fffe0000010200(slab|head)
[ 20.536795] raw: 03fffe0000010200 0000000000000100 0000000000000200 000000008ff88600
[ 20.536796] raw: 0000000000000000 0020004100000000 ffffffff00000001 0000000000000000
[ 20.536797] page dumped because: has_unmovable_pages
[ 20.536814] page:000003d0823b0000 count:1 mapcount:0 mapping:0000000000000000 index:0x0
[ 20.536815] flags: 0x7fffe0000000000()
[ 20.536817] raw: 07fffe0000000000 0000000000000100 0000000000000200 0000000000000000
[ 20.536818] raw: 0000000000000000 0000000000000000 ffffffff00000001 0000000000000000
which are not triggered by the memory hotplug but rather CMA allocator.
The original idea behind dumping the page state for all call paths was
that these messages will be helpful debugging failures. From the above it
seems that this is not the case for the CMA path because we are lacking
much more context. E.g the second reported page might be a CMA allocated
page. It is still interesting to see a slab page in the CMA area but it
is hard to tell whether this is bug from the above output alone.
Address this issue by dumping the page state only on request. Both
start_isolate_page_range and has_unmovable_pages already have an argument
to ignore hwpoison pages so make this argument more generic and turn it
into flags and allow callers to combine non-default modes into a mask.
While we are at it, has_unmovable_pages call from
is_pageblock_removable_nolock (sysfs removable file) is questionable to
report the failure so drop it from there as well.
Link: http://lkml.kernel.org/r/20181218092802.31429-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is only very limited information printed when the memory offlining
fails:
[ 1984.506184] rac1 kernel: memory offlining [mem 0x82600000000-0x8267fffffff] failed due to signal backoff
This tells us that the failure is triggered by the userspace intervention
but it doesn't tell us much more about the underlying reason. It might be
that the page migration failes repeatedly and the userspace timeout
expires and send a signal or it might be some of the earlier steps
(isolation, memory notifier) takes too long.
If the migration failes then it would be really helpful to see which page
that and its state. The same applies to the isolation phase. If we fail
to isolate a page from the allocator then knowing the state of the page
would be helpful as well.
Dump the page state that fails to get isolated or migrated. This will
tell us more about the failure and what to focus on during debugging.
[akpm@linux-foundation.org: add missing printk arg]
[mhocko@suse.com: tweak dump_page() `reason' text]
Link: http://lkml.kernel.org/r/20181116083020.20260-6-mhocko@kernel.org
Link: http://lkml.kernel.org/r/20181107101830.17405-6-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Oscar Salvador <OSalvador@suse.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The memory offlining failure reporting is inconsistent and insufficient.
Some error paths simply do not report the failure to the log at all. When
we do report there are no details about the reason of the failure and
there are several of them which makes memory offlining failures hard to
debug.
Make sure that the
memory offlining [mem %#010llx-%#010llx] failed
message is printed for all failures and also provide a short textual
reason for the failure e.g.
[ 1984.506184] rac1 kernel: memory offlining [mem 0x82600000000-0x8267fffffff] failed due to signal backoff
this tells us that the offlining has failed because of a signal pending
aka user intervention.
[akpm@linux-foundation.org: tweak messages a bit]
Link: http://lkml.kernel.org/r/20181107101830.17405-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Oscar Salvador <OSalvador@suse.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This function is never called from a context which would provide
misaligned pfn range so drop the pointless check.
Link: http://lkml.kernel.org/r/20181107101830.17405-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Oscar Salvador <OSalvador@suse.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have received a bug report that unbinding a large pmem (>1TB) can
result in a soft lockup:
NMI watchdog: BUG: soft lockup - CPU#9 stuck for 23s! [ndctl:4365]
[...]
Supported: Yes
CPU: 9 PID: 4365 Comm: ndctl Not tainted 4.12.14-94.40-default #1 SLE12-SP4
Hardware name: Intel Corporation S2600WFD/S2600WFD, BIOS SE5C620.86B.01.00.0833.051120182255 05/11/2018
task: ffff9cce7d4410c0 task.stack: ffffbe9eb1bc4000
RIP: 0010:__put_page+0x62/0x80
Call Trace:
devm_memremap_pages_release+0x152/0x260
release_nodes+0x18d/0x1d0
device_release_driver_internal+0x160/0x210
unbind_store+0xb3/0xe0
kernfs_fop_write+0x102/0x180
__vfs_write+0x26/0x150
vfs_write+0xad/0x1a0
SyS_write+0x42/0x90
do_syscall_64+0x74/0x150
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x7fd13166b3d0
It has been reported on an older (4.12) kernel but the current upstream
code doesn't cond_resched in the hot remove code at all and the given
range to remove might be really large. Fix the issue by calling
cond_resched once per memory section.
Link: http://lkml.kernel.org/r/20181031125840.23982-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Dan Williams <dan.j.williams@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There seem to be some problems as result of 30467e0b3b ("mm, hotplug:
fix concurrent memory hot-add deadlock"), which tried to fix a possible
lock inversion reported and discussed in [1] due to the two locks
a) device_lock()
b) mem_hotplug_lock
While add_memory() first takes b), followed by a) during
bus_probe_device(), onlining of memory from user space first took a),
followed by b), exposing a possible deadlock.
In [1], and it was decided to not make use of device_hotplug_lock, but
rather to enforce a locking order.
The problems I spotted related to this:
1. Memory block device attributes: While .state first calls
mem_hotplug_begin() and the calls device_online() - which takes
device_lock() - .online does no longer call mem_hotplug_begin(), so
effectively calls online_pages() without mem_hotplug_lock.
2. device_online() should be called under device_hotplug_lock, however
onlining memory during add_memory() does not take care of that.
In addition, I think there is also something wrong about the locking in
3. arch/powerpc/platforms/powernv/memtrace.c calls offline_pages()
without locks. This was introduced after 30467e0b3b. And skimming over
the code, I assume it could need some more care in regards to locking
(e.g. device_online() called without device_hotplug_lock. This will
be addressed in the following patches.
Now that we hold the device_hotplug_lock when
- adding memory (e.g. via add_memory()/add_memory_resource())
- removing memory (e.g. via remove_memory())
- device_online()/device_offline()
We can move mem_hotplug_lock usage back into
online_pages()/offline_pages().
Why is mem_hotplug_lock still needed? Essentially to make
get_online_mems()/put_online_mems() be very fast (relying on
device_hotplug_lock would be very slow), and to serialize against
addition of memory that does not create memory block devices (hmm).
[1] http://driverdev.linuxdriverproject.org/pipermail/ driverdev-devel/
2015-February/065324.html
This patch is partly based on a patch by Vitaly Kuznetsov.
Link: http://lkml.kernel.org/r/20180925091457.28651-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Rashmica Gupta <rashmica.g@gmail.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
add_memory() currently does not take the device_hotplug_lock, however
is aleady called under the lock from
arch/powerpc/platforms/pseries/hotplug-memory.c
drivers/acpi/acpi_memhotplug.c
to synchronize against CPU hot-remove and similar.
In general, we should hold the device_hotplug_lock when adding memory to
synchronize against online/offline request (e.g. from user space) - which
already resulted in lock inversions due to device_lock() and
mem_hotplug_lock - see 30467e0b3b ("mm, hotplug: fix concurrent memory
hot-add deadlock"). add_memory()/add_memory_resource() will create memory
block devices, so this really feels like the right thing to do.
Holding the device_hotplug_lock makes sure that a memory block device
can really only be accessed (e.g. via .online/.state) from user space,
once the memory has been fully added to the system.
The lock is not held yet in
drivers/xen/balloon.c
arch/powerpc/platforms/powernv/memtrace.c
drivers/s390/char/sclp_cmd.c
drivers/hv/hv_balloon.c
So, let's either use the locked variants or take the lock.
Don't export add_memory_resource(), as it once was exported to be used by
XEN, which is never built as a module. If somebody requires it, we also
have to export a locked variant (as device_hotplug_lock is never
exported).
Link: http://lkml.kernel.org/r/20180925091457.28651-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: online/offline_pages called w.o. mem_hotplug_lock", v3.
Reading through the code and studying how mem_hotplug_lock is to be used,
I noticed that there are two places where we can end up calling
device_online()/device_offline() - online_pages()/offline_pages() without
the mem_hotplug_lock. And there are other places where we call
device_online()/device_offline() without the device_hotplug_lock.
While e.g.
echo "online" > /sys/devices/system/memory/memory9/state
is fine, e.g.
echo 1 > /sys/devices/system/memory/memory9/online
Will not take the mem_hotplug_lock. However the device_lock() and
device_hotplug_lock.
E.g. via memory_probe_store(), we can end up calling
add_memory()->online_pages() without the device_hotplug_lock. So we can
have concurrent callers in online_pages(). We e.g. touch in
online_pages() basically unprotected zone->present_pages then.
Looks like there is a longer history to that (see Patch #2 for details),
and fixing it to work the way it was intended is not really possible. We
would e.g. have to take the mem_hotplug_lock in device/base/core.c, which
sounds wrong.
Summary: We had a lock inversion on mem_hotplug_lock and device_lock().
More details can be found in patch 3 and patch 6.
I propose the general rules (documentation added in patch 6):
1. add_memory/add_memory_resource() must only be called with
device_hotplug_lock.
2. remove_memory() must only be called with device_hotplug_lock. This is
already documented and holds for all callers.
3. device_online()/device_offline() must only be called with
device_hotplug_lock. This is already documented and true for now in core
code. Other callers (related to memory hotplug) have to be fixed up.
4. mem_hotplug_lock is taken inside of add_memory/remove_memory/
online_pages/offline_pages.
To me, this looks way cleaner than what we have right now (and easier to
verify). And looking at the documentation of remove_memory, using
lock_device_hotplug also for add_memory() feels natural.
This patch (of 6):
remove_memory() is exported right now but requires the
device_hotplug_lock, which is not exported. So let's provide a variant
that takes the lock and only export that one.
The lock is already held in
arch/powerpc/platforms/pseries/hotplug-memory.c
drivers/acpi/acpi_memhotplug.c
arch/powerpc/platforms/powernv/memtrace.c
Apart from that, there are not other users in the tree.
Link: http://lkml.kernel.org/r/20180925091457.28651-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Rashmica Gupta <rashmica.g@gmail.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move remaining definitions and declarations from include/linux/bootmem.h
into include/linux/memblock.h and remove the redundant header.
The includes were replaced with the semantic patch below and then
semi-automated removal of duplicated '#include <linux/memblock.h>
@@
@@
- #include <linux/bootmem.h>
+ #include <linux/memblock.h>
[sfr@canb.auug.org.au: dma-direct: fix up for the removal of linux/bootmem.h]
Link: http://lkml.kernel.org/r/20181002185342.133d1680@canb.auug.org.au
[sfr@canb.auug.org.au: powerpc: fix up for removal of linux/bootmem.h]
Link: http://lkml.kernel.org/r/20181005161406.73ef8727@canb.auug.org.au
[sfr@canb.auug.org.au: x86/kaslr, ACPI/NUMA: fix for linux/bootmem.h removal]
Link: http://lkml.kernel.org/r/20181008190341.5e396491@canb.auug.org.au
Link: http://lkml.kernel.org/r/1536927045-23536-30-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Serge Semin <fancer.lancer@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch, as the previous one, gets rid of the wrong if statements.
While at it, I realized that the comments are sometimes very confusing,
to say the least, and wrong.
For example:
___
zone_last = ZONE_MOVABLE;
/*
* check whether node_states[N_HIGH_MEMORY] will be changed
* If we try to offline the last present @nr_pages from the node,
* we can determind we will need to clear the node from
* node_states[N_HIGH_MEMORY].
*/
for (; zt <= zone_last; zt++)
present_pages += pgdat->node_zones[zt].present_pages;
if (nr_pages >= present_pages)
arg->status_change_nid = zone_to_nid(zone);
else
arg->status_change_nid = -1;
___
In case the node gets empry, it must be removed from N_MEMORY. We already
check N_HIGH_MEMORY a bit above within the CONFIG_HIGHMEM ifdef code. Not
to say that status_change_nid is for N_MEMORY, and not for N_HIGH_MEMORY.
So I re-wrote some of the comments to what I think is better.
[osalvador@suse.de: address feedback from Pavel]
Link: http://lkml.kernel.org/r/20180921132634.10103-5-osalvador@techadventures.net
Link: http://lkml.kernel.org/r/20180919100819.25518-6-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: <yasu.isimatu@gmail.com>
Cc: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While looking at node_states_check_changes_online, I stumbled upon some
confusing things.
Right after entering the function, we find this:
if (N_MEMORY == N_NORMAL_MEMORY)
zone_last = ZONE_MOVABLE;
This is wrong.
N_MEMORY cannot really be equal to N_NORMAL_MEMORY.
My guess is that this wanted to be something like:
if (N_NORMAL_MEMORY == N_HIGH_MEMORY)
to check if we have CONFIG_HIGHMEM.
Later on, in the CONFIG_HIGHMEM block, we have:
if (N_MEMORY == N_HIGH_MEMORY)
zone_last = ZONE_MOVABLE;
Again, this is wrong, and will never be evaluated to true.
Besides removing these wrong if statements, I simplified the function a
bit.
[osalvador@suse.de: address feedback from Pavel]
Link: http://lkml.kernel.org/r/20180921132634.10103-4-osalvador@techadventures.net
Link: http://lkml.kernel.org/r/20180919100819.25518-5-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <yasu.isimatu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
node_states_clear has the following if statements:
if ((N_MEMORY != N_NORMAL_MEMORY) &&
(arg->status_change_nid_high >= 0))
...
if ((N_MEMORY != N_HIGH_MEMORY) &&
(arg->status_change_nid >= 0))
...
N_MEMORY can never be equal to neither N_NORMAL_MEMORY nor
N_HIGH_MEMORY.
Similar problem was found in [1].
Since this is wrong, let us get rid of it.
[1] https://patchwork.kernel.org/patch/10579155/
Link: http://lkml.kernel.org/r/20180919100819.25518-4-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <yasu.isimatu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In node_states_check_changes_online, we check if the node will have to be
set for any of the N_*_MEMORY states after the pages have been onlined.
Later on, we perform the activation in node_states_set_node. Currently,
in node_states_set_node we set the node to N_MEMORY unconditionally.
This means that we call node_set_state for N_MEMORY every time pages go
online, but we only need to do it if the node has not yet been set for
N_MEMORY.
Fix this by checking status_change_nid.
Link: http://lkml.kernel.org/r/20180919100819.25518-2-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: <yasu.isimatu@gmail.com>
Cc: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When scanning for movable pages, filter out Hugetlb pages if hugepage
migration is not supported. Without this we hit infinte loop in
__offline_pages() where we do
pfn = scan_movable_pages(start_pfn, end_pfn);
if (pfn) { /* We have movable pages */
ret = do_migrate_range(pfn, end_pfn);
goto repeat;
}
Fix this by checking hugepage_migration_supported both in
has_unmovable_pages which is the primary backoff mechanism for page
offlining and for consistency reasons also into scan_movable_pages
because it doesn't make any sense to return a pfn to non-migrateable
huge page.
This issue was revealed by, but not caused by 72b39cfc4d ("mm,
memory_hotplug: do not fail offlining too early").
Link: http://lkml.kernel.org/r/20180824063314.21981-1-aneesh.kumar@linux.ibm.com
Fixes: 72b39cfc4d ("mm, memory_hotplug: do not fail offlining too early")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reported-by: Haren Myneni <haren@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, whenever a new node is created/re-used from the memhotplug
path, we call free_area_init_node()->free_area_init_core(). But there is
some code that we do not really need to run when we are coming from such
path.
free_area_init_core() performs the following actions:
1) Initializes pgdat internals, such as spinlock, waitqueues and more.
2) Account # nr_all_pages and # nr_kernel_pages. These values are used later on
when creating hash tables.
3) Account number of managed_pages per zone, substracting dma_reserved and
memmap pages.
4) Initializes some fields of the zone structure data
5) Calls init_currently_empty_zone to initialize all the freelists
6) Calls memmap_init to initialize all pages belonging to certain zone
When called from memhotplug path, free_area_init_core() only performs
actions #1 and #4.
Action #2 is pointless as the zones do not have any pages since either the
node was freed, or we are re-using it, eitherway all zones belonging to
this node should have 0 pages. For the same reason, action #3 results
always in manages_pages being 0.
Action #5 and #6 are performed later on when onlining the pages:
online_pages()->move_pfn_range_to_zone()->init_currently_empty_zone()
online_pages()->move_pfn_range_to_zone()->memmap_init_zone()
This patch does two things:
First, moves the node/zone initializtion to their own function, so it
allows us to create a small version of free_area_init_core, where we only
perform:
1) Initialization of pgdat internals, such as spinlock, waitqueues and more
4) Initialization of some fields of the zone structure data
These two functions are: pgdat_init_internals() and zone_init_internals().
The second thing this patch does, is to introduce
free_area_init_core_hotplug(), the memhotplug version of
free_area_init_core():
Currently, we call free_area_init_node() from the memhotplug path. In
there, we set some pgdat's fields, and call calculate_node_totalpages().
calculate_node_totalpages() calculates the # of pages the node has.
Since the node is either new, or we are re-using it, the zones belonging
to this node should not have any pages, so there is no point to calculate
this now.
Actually, we re-set these values to 0 later on with the calls to:
reset_node_managed_pages()
reset_node_present_pages()
The # of pages per node and the # of pages per zone will be calculated when
onlining the pages:
online_pages()->move_pfn_range()->move_pfn_range_to_zone()->resize_zone_range()
online_pages()->move_pfn_range()->move_pfn_range_to_zone()->resize_pgdat_range()
Also, since free_area_init_core/free_area_init_node will now only get called during early init, let us replace
__paginginit with __init, so their code gets freed up.
[osalvador@techadventures.net: fix section usage]
Link: http://lkml.kernel.org/r/20180731101752.GA473@techadventures.net
[osalvador@suse.de: v6]
Link: http://lkml.kernel.org/r/20180801122348.21588-6-osalvador@techadventures.net
Link: http://lkml.kernel.org/r/20180730101757.28058-5-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
link_mem_sections() and walk_memory_range() share most of the code, so
we can use convert link_mem_sections() into a dummy function that calls
walk_memory_range() with a callback to register_mem_sect_under_node().
This patch converts register_mem_sect_under_node() in order to match a
walk_memory_range's callback, getting rid of the check_nid argument and
checking instead if the system is still boothing, since we only have to
check for the nid if the system is in such state.
Link: http://lkml.kernel.org/r/20180622111839.10071-4-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Suggested-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When hotplugging memory, it is possible that two calls are being made to
register_mem_sect_under_node().
One comes from __add_section()->hotplug_memory_register() and the other
from add_memory_resource()->link_mem_sections() if we had to register a
new node.
In case we had to register a new node, hotplug_memory_register() will
only handle/allocate the memory_block's since
register_mem_sect_under_node() will return right away because the node
it is not online yet.
I think it is better if we leave hotplug_memory_register() to
handle/allocate only memory_block's and make link_mem_sections() to call
register_mem_sect_under_node().
So this patch removes the call to register_mem_sect_under_node() from
hotplug_memory_register(), and moves the call to link_mem_sections() out
of the condition, so it will always be called. In this way we only have
one place where the memory sections are registered.
Link: http://lkml.kernel.org/r/20180622111839.10071-3-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a small cleanup for the memhotplug code. A lot more could be
done, but it is better to start somewhere. I tried to unify/remove
duplicated code.
The following is what this patchset does:
1) add_memory_resource() has code to allocate a node in case it was
offline. Since try_online_node has some code for that as well, I just
made add_memory_resource() to use that so we can remove duplicated
code.. This is better explained in patch 1/4.
2) register_mem_sect_under_node() will be called only from
link_mem_sections()
3) Make register_mem_sect_under_node() a callback of
walk_memory_range()
4) Drop unnecessary checks from register_mem_sect_under_node()
I have done some tests and I could not see anything broken because of
this patchset.
add_memory_resource() contains code to allocate a new node in case it is
necessary. Since try_online_node() also has some code for this purpose,
let us make use of that and remove duplicate code.
This introduces __try_online_node(), which is called by
add_memory_resource() and try_online_node(). __try_online_node() has
two new parameters, start_addr of the node, and if the node should be
onlined and registered right away. This is always wanted if we are
calling from do_cpu_up(), but not when we are calling from memhotplug
code. Nothing changes from the point of view of the users of
try_online_node(), since try_online_node passes start_addr=0 and
online_node=true to __try_online_node().
Link: http://lkml.kernel.org/r/20180622111839.10071-2-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
is_pageblock_removable_nolock() is not used outside of
mm/memory_hotplug.c. Move it next to unique caller
is_mem_section_removable() and make it static.
Remove prototype in <linux/memory_hotplug.h> to silence gcc warning (W=1):
mm/page_alloc.c:7704:6: warning: no previous prototype for `is_pageblock_removable_nolock' [-Wmissing-prototypes]
Link: http://lkml.kernel.org/r/20180509190001.24789-1-malat@debian.org
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The case of a new numa node got missed in avoiding using the node info
from page_struct during hotplug. In this path we have a call to
register_mem_sect_under_node (which allows us to specify it is hotplug
so don't change the node), via link_mem_sections which unfortunately
does not.
Fix is to pass check_nid through link_mem_sections as well and disable
it in the new numa node path.
Note the bug only 'sometimes' manifests depending on what happens to be
in the struct page structures - there are lots of them and it only needs
to match one of them.
The result of the bug is that (with a new memory only node) we never
successfully call register_mem_sect_under_node so don't get the memory
associated with the node in sysfs and meminfo for the node doesn't
report it.
It came up whilst testing some arm64 hotplug patches, but appears to be
universal. Whilst I'm triggering it by removing then reinserting memory
to a node with no other elements (thus making the node disappear then
appear again), it appears it would happen on hotplugging memory where
there was none before and it doesn't seem to be related the arm64
patches.
These patches call __add_pages (where most of the issue was fixed by
Pavel's patch). If there is a node at the time of the __add_pages call
then all is well as it calls register_mem_sect_under_node from there
with check_nid set to false. Without a node that function returns
having not done the sysfs related stuff as there is no node to use.
This is expected but it is the resulting path that fails...
Exact path to the problem is as follows:
mm/memory_hotplug.c: add_memory_resource()
The node is not online so we enter the 'if (new_node)' twice, on the
second such block there is a call to link_mem_sections which calls
into
drivers/node.c: link_mem_sections() which calls
drivers/node.c: register_mem_sect_under_node() which calls
get_nid_for_pfn and keeps trying until the output of that matches
the expected node (passed all the way down from
add_memory_resource)
It is effectively the same fix as the one referred to in the fixes tag
just in the code path for a new node where the comments point out we
have to rerun the link creation because it will have failed in
register_new_memory (as there was no node at the time). (actually that
comment is wrong now as we don't have register_new_memory any more it
got renamed to hotplug_memory_register in Pavel's patch).
Link: http://lkml.kernel.org/r/20180504085311.1240-1-Jonathan.Cameron@huawei.com
Fixes: fc44f7f923 ("mm/memory_hotplug: don't read nid from struct page during hotplug")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
THP migration is hacked into the generic migration with rather
surprising semantic. The migration allocation callback is supposed to
check whether the THP can be migrated at once and if that is not the
case then it allocates a simple page to migrate. unmap_and_move then
fixes that up by spliting the THP into small pages while moving the head
page to the newly allocated order-0 page. Remaning pages are moved to
the LRU list by split_huge_page. The same happens if the THP allocation
fails. This is really ugly and error prone [1].
I also believe that split_huge_page to the LRU lists is inherently wrong
because all tail pages are not migrated. Some callers will just work
around that by retrying (e.g. memory hotplug). There are other pfn
walkers which are simply broken though. e.g. madvise_inject_error will
migrate head and then advances next pfn by the huge page size.
do_move_page_to_node_array, queue_pages_range (migrate_pages, mbind),
will simply split the THP before migration if the THP migration is not
supported then falls back to single page migration but it doesn't handle
tail pages if the THP migration path is not able to allocate a fresh THP
so we end up with ENOMEM and fail the whole migration which is a
questionable behavior. Page compaction doesn't try to migrate large
pages so it should be immune.
This patch tries to unclutter the situation by moving the special THP
handling up to the migrate_pages layer where it actually belongs. We
simply split the THP page into the existing list if unmap_and_move fails
with ENOMEM and retry. So we will _always_ migrate all THP subpages and
specific migrate_pages users do not have to deal with this case in a
special way.
[1] http://lkml.kernel.org/r/20171121021855.50525-1-zi.yan@sent.com
Link: http://lkml.kernel.org/r/20180103082555.14592-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Andrea Reale <ar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No allocation callback is using this argument anymore. new_page_node
used to use this parameter to convey node_id resp. migration error up
to move_pages code (do_move_page_to_node_array). The error status never
made it into the final status field and we have a better way to
communicate node id to the status field now. All other allocation
callbacks simply ignored the argument so we can drop it finally.
[mhocko@suse.com: fix migration callback]
Link: http://lkml.kernel.org/r/20180105085259.GH2801@dhcp22.suse.cz
[akpm@linux-foundation.org: fix alloc_misplaced_dst_page()]
[mhocko@kernel.org: fix build]
Link: http://lkml.kernel.org/r/20180103091134.GB11319@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20180103082555.14592-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Andrea Reale <ar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During memory hotplugging we traverse struct pages three times:
1. memset(0) in sparse_add_one_section()
2. loop in __add_section() to set do: set_page_node(page, nid); and
SetPageReserved(page);
3. loop in memmap_init_zone() to call __init_single_pfn()
This patch removes the first two loops, and leaves only loop 3. All
struct pages are initialized in one place, the same as it is done during
boot.
The benefits:
- We improve memory hotplug performance because we are not evicting the
cache several times and also reduce loop branching overhead.
- Remove condition from hotpath in __init_single_pfn(), that was added
in order to fix the problem that was reported by Bharata in the above
email thread, thus also improve performance during normal boot.
- Make memory hotplug more similar to the boot memory initialization
path because we zero and initialize struct pages only in one
function.
- Simplifies memory hotplug struct page initialization code, and thus
enables future improvements, such as multi-threading the
initialization of struct pages in order to improve hotplug
performance even further on larger machines.
[pasha.tatashin@oracle.com: v5]
Link: http://lkml.kernel.org/r/20180228030308.1116-7-pasha.tatashin@oracle.com
Link: http://lkml.kernel.org/r/20180215165920.8570-7-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During memory hotplugging the probe routine will leave struct pages
uninitialized, the same as it is currently done during boot. Therefore,
we do not want to access the inside of struct pages before
__init_single_page() is called during onlining.
Because during hotplug we know that pages in one memory block belong to
the same numa node, we can skip the checking. We should keep checking
for the boot case.
[pasha.tatashin@oracle.com: s/register_new_memory()/hotplug_memory_register()]
Link: http://lkml.kernel.org/r/20180228030308.1116-6-pasha.tatashin@oracle.com
Link: http://lkml.kernel.org/r/20180215165920.8570-6-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "optimize memory hotplug", v3.
This patchset:
- Improves hotplug performance by eliminating a number of struct page
traverses during memory hotplug.
- Fixes some issues with hotplugging, where boundaries were not
properly checked. And on x86 block size was not properly aligned with
end of memory
- Also, potentially improves boot performance by eliminating condition
from __init_single_page().
- Adds robustness by verifying that that struct pages are correctly
poisoned when flags are accessed.
The following experiments were performed on Xeon(R) CPU E7-8895 v3 @
2.60GHz with 1T RAM:
booting in qemu with 960G of memory, time to initialize struct pages:
no-kvm:
TRY1 TRY2
BEFORE: 39.433668 39.39705
AFTER: 36.903781 36.989329
with-kvm:
BEFORE: 10.977447 11.103164
AFTER: 10.929072 10.751885
Hotplug 896G memory:
no-kvm:
TRY1 TRY2
BEFORE: 848.740000 846.910000
AFTER: 783.070000 786.560000
with-kvm:
TRY1 TRY2
BEFORE: 34.410000 33.57
AFTER: 29.810000 29.580000
This patch (of 6):
Start qemu with the following arguments:
-m 64G,slots=2,maxmem=66G -object memory-backend-ram,id=mem1,size=2G
Which: boots machine with 64G, and adds a device mem1 with 2G which can
be hotplugged later.
Also make sure that config has the following turned on:
CONFIG_MEMORY_HOTPLUG
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
CONFIG_ACPI_HOTPLUG_MEMORY
Using the qemu monitor hotplug the memory (make sure config has (qemu)
device_add pc-dimm,id=dimm1,memdev=mem1
The operation will fail with the following trace:
WARNING: CPU: 0 PID: 91 at drivers/base/memory.c:205
pages_correctly_reserved+0xe6/0x110
Modules linked in:
CPU: 0 PID: 91 Comm: systemd-udevd Not tainted 4.16.0-rc1_pt_master #29
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014
RIP: 0010:pages_correctly_reserved+0xe6/0x110
Call Trace:
memory_subsys_online+0x44/0xa0
device_online+0x51/0x80
store_mem_state+0x5e/0xe0
kernfs_fop_write+0xfa/0x170
__vfs_write+0x2e/0x150
vfs_write+0xa8/0x1a0
SyS_write+0x4d/0xb0
do_syscall_64+0x5d/0x110
entry_SYSCALL_64_after_hwframe+0x21/0x86
---[ end trace 6203bc4f1a5d30e8 ]---
The problem is detected in: drivers/base/memory.c
static bool pages_correctly_reserved(unsigned long start_pfn)
205 if (WARN_ON_ONCE(!pfn_valid(pfn)))
This function loops through every section in the newly added memory
block and verifies that the first pfn is valid, meaning section exists,
has mapping (struct page array), and is online.
The block size on x86 is usually 128M, but when machine is booted with
more than 64G of memory, the block size is changed to 2G: $ cat
/sys/devices/system/memory/block_size_bytes 80000000
or
$ dmesg | grep "block size"
[ 0.086469] x86/mm: Memory block size: 2048MB
During memory hotplug, and hotremove we verify that the range is section
size aligned, but we actually must verify that it is block size aligned,
because that is the proper unit for hotplug operations. See:
Documentation/memory-hotplug.txt
So, when the start_pfn of newly added memory is not block size aligned,
we can get a memory block that has only part of it with properly
populated sections.
In our case the start_pfn starts from the last_pfn (end of physical
memory).
$ dmesg | grep last_pfn
[ 0.000000] e820: last_pfn = 0x1040000 max_arch_pfn = 0x400000000
0x1040000 == 65G, and so is not 2G aligned!
The fix is to enforce that memory that is hotplugged and hotremoved is
block size aligned.
With this fix, running the above sequence yield to the following result:
(qemu) device_add pc-dimm,id=dimm1,memdev=mem1
Block size [0x80000000] unaligned hotplug range: start 0x1040000000,
size 0x80000000
acpi PNP0C80:00: add_memory failed
acpi PNP0C80:00: acpi_memory_enable_device() error
acpi PNP0C80:00: Enumeration failure
Link: http://lkml.kernel.org/r/20180213193159.14606-2-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds