<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/git/stable/linux.git/mm/memory-failure.c, branch linux-5.17.y</title>
<subtitle>Linux kernel stable tree</subtitle>
<id>https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/atom?h=linux-5.17.y</id>
<link rel='self' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/atom?h=linux-5.17.y'/>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/'/>
<updated>2022-05-18T08:28:23+00:00</updated>
<entry>
<title>mm/hwpoison: use pr_err() instead of dump_page() in get_any_page()</title>
<updated>2022-05-18T08:28:23+00:00</updated>
<author>
<name>Naoya Horiguchi</name>
<email>naoya.horiguchi@nec.com</email>
</author>
<published>2022-04-29T06:14:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4f6d1d30ce0f56b24e71f359d7a98f93dad573a3'/>
<id>urn:sha1:4f6d1d30ce0f56b24e71f359d7a98f93dad573a3</id>
<content type='text'>
commit 1825b93b626e99eb9a0f9f50342c7b2fa201b387 upstream.

The following VM_BUG_ON_FOLIO() is triggered when memory error event
happens on the (thp/folio) pages which are about to be freed:

  [ 1160.232771] page:00000000b36a8a0f refcount:1 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x16a000
  [ 1160.236916] page:00000000b36a8a0f refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x16a000
  [ 1160.240684] flags: 0x57ffffc0800000(hwpoison|node=1|zone=2|lastcpupid=0x1fffff)
  [ 1160.243458] raw: 0057ffffc0800000 dead000000000100 dead000000000122 0000000000000000
  [ 1160.246268] raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
  [ 1160.249197] page dumped because: VM_BUG_ON_FOLIO(!folio_test_large(folio))
  [ 1160.251815] ------------[ cut here ]------------
  [ 1160.253438] kernel BUG at include/linux/mm.h:788!
  [ 1160.256162] invalid opcode: 0000 [#1] PREEMPT SMP PTI
  [ 1160.258172] CPU: 2 PID: 115368 Comm: mceinj.sh Tainted: G            E     5.18.0-rc1-v5.18-rc1-220404-2353-005-g83111+ #3
  [ 1160.262049] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1.fc35 04/01/2014
  [ 1160.265103] RIP: 0010:dump_page.cold+0x27e/0x2bd
  [ 1160.266757] Code: fe ff ff 48 c7 c6 81 f1 5a 98 e9 4c fe ff ff 48 c7 c6 a1 95 59 98 e9 40 fe ff ff 48 c7 c6 50 bf 5a 98 48 89 ef e8 9d 04 6d ff &lt;0f&gt; 0b 41 f7 c4 ff 0f 00 00 0f 85 9f fd ff ff 49 8b 04 24 a9 00 00
  [ 1160.273180] RSP: 0018:ffffaa2c4d59fd18 EFLAGS: 00010292
  [ 1160.274969] RAX: 000000000000003e RBX: 0000000000000001 RCX: 0000000000000000
  [ 1160.277263] RDX: 0000000000000001 RSI: ffffffff985995a1 RDI: 00000000ffffffff
  [ 1160.279571] RBP: ffffdc9c45a80000 R08: 0000000000000000 R09: 00000000ffffdfff
  [ 1160.281794] R10: ffffaa2c4d59fb08 R11: ffffffff98940d08 R12: ffffdc9c45a80000
  [ 1160.283920] R13: ffffffff985b6f94 R14: 0000000000000000 R15: ffffdc9c45a80000
  [ 1160.286641] FS:  00007eff54ce1740(0000) GS:ffff99c67bd00000(0000) knlGS:0000000000000000
  [ 1160.289498] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [ 1160.291106] CR2: 00005628381a5f68 CR3: 0000000104712003 CR4: 0000000000170ee0
  [ 1160.293031] Call Trace:
  [ 1160.293724]  &lt;TASK&gt;
  [ 1160.294334]  get_hwpoison_page+0x47d/0x570
  [ 1160.295474]  memory_failure+0x106/0xaa0
  [ 1160.296474]  ? security_capable+0x36/0x50
  [ 1160.297524]  hard_offline_page_store+0x43/0x80
  [ 1160.298684]  kernfs_fop_write_iter+0x11c/0x1b0
  [ 1160.299829]  new_sync_write+0xf9/0x160
  [ 1160.300810]  vfs_write+0x209/0x290
  [ 1160.301835]  ksys_write+0x4f/0xc0
  [ 1160.302718]  do_syscall_64+0x3b/0x90
  [ 1160.303664]  entry_SYSCALL_64_after_hwframe+0x44/0xae
  [ 1160.304981] RIP: 0033:0x7eff54b018b7

As shown in the RIP address, this VM_BUG_ON in folio_entire_mapcount() is
called from dump_page("hwpoison: unhandlable page") in get_any_page().
The below explains the mechanism of the race:

  CPU 0                                       CPU 1

    memory_failure
      get_hwpoison_page
        get_any_page
          dump_page
            compound = PageCompound
                                                free_pages_prepare
                                                  page-&gt;flags &amp;= ~PAGE_FLAGS_CHECK_AT_PREP
            folio_entire_mapcount
              VM_BUG_ON_FOLIO(!folio_test_large(folio))

So replace dump_page() with safer one, pr_err().

Link: https://lkml.kernel.org/r/20220427053220.719866-1-naoya.horiguchi@linux.dev
Fixes: 74e8ee4708a8 ("mm: Turn head_compound_mapcount() into folio_entire_mapcount()")
Signed-off-by: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Reviewed-by: John Hubbard &lt;jhubbard@nvidia.com&gt;
Reviewed-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
Cc: Jason Gunthorpe &lt;jgg@nvidia.com&gt;
Cc: William Kucharski &lt;william.kucharski@oracle.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>Revert "mm/memory-failure.c: skip huge_zero_page in memory_failure()"</title>
<updated>2022-05-18T08:28:21+00:00</updated>
<author>
<name>Xu Yu</name>
<email>xuyu@linux.alibaba.com</email>
</author>
<published>2022-04-29T06:14:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=86079983c0f255e78649b41885762d2907801274'/>
<id>urn:sha1:86079983c0f255e78649b41885762d2907801274</id>
<content type='text'>
commit b4e61fc031b11dd807dffc46cebbf0e25966d3d1 upstream.

Patch series "mm/memory-failure: rework fix on huge_zero_page splitting".


This patch (of 2):

This reverts commit d173d5417fb67411e623d394aab986d847e47dad.

The commit d173d5417fb6 ("mm/memory-failure.c: skip huge_zero_page in
memory_failure()") explicitly skips huge_zero_page in memory_failure(), in
order to avoid triggering VM_BUG_ON_PAGE on huge_zero_page in
split_huge_page_to_list().

This works, but Yang Shi thinks that,

    Raising BUG is overkilling for splitting huge_zero_page. The
    huge_zero_page can't be met from normal paths other than memory
    failure, but memory failure is a valid caller. So I tend to replace
    the BUG to WARN + returning -EBUSY. If we don't care about the
    reason code in memory failure, we don't have to touch memory
    failure.

And for the issue that huge_zero_page will be set PG_has_hwpoisoned,
Yang Shi comments that,

    The anonymous page fault doesn't check if the page is poisoned or
    not since it typically gets a fresh allocated page and assumes the
    poisoned page (isolated successfully) can't be reallocated again.
    But huge zero page and base zero page are reused every time. So no
    matter what fix we pick, the issue is always there.

Finally, Yang, David, Anshuman and Naoya all agree to fix the bug, i.e.,
to split huge_zero_page, in split_huge_page_to_list().

This reverts the commit d173d5417fb6 ("mm/memory-failure.c: skip
huge_zero_page in memory_failure()"), and the original bug will be fixed
by the next patch.

Link: https://lkml.kernel.org/r/872cefb182ba1dd686b0e7db1e6b2ebe5a4fff87.1651039624.git.xuyu@linux.alibaba.com
Fixes: d173d5417fb6 ("mm/memory-failure.c: skip huge_zero_page in memory_failure()")
Fixes: 6a46079cf57a ("HWPOISON: The high level memory error handler in the VM v7")
Signed-off-by: Xu Yu &lt;xuyu@linux.alibaba.com&gt;
Suggested-by: Yang Shi &lt;shy828301@gmail.com&gt;
Reviewed-by: Yang Shi &lt;shy828301@gmail.com&gt;
Reviewed-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mm/hwpoison: fix error page recovered but reported "not recovered"</title>
<updated>2022-05-15T18:20:53+00:00</updated>
<author>
<name>Naoya Horiguchi</name>
<email>naoya.horiguchi@nec.com</email>
</author>
<published>2022-03-22T21:44:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=db3e489eeb40813c7b91fe41f0f9a094106d330c'/>
<id>urn:sha1:db3e489eeb40813c7b91fe41f0f9a094106d330c</id>
<content type='text'>
commit 046545a661af2beec21de7b90ca0e35f05088a81 upstream.

When an uncorrected memory error is consumed there is a race between the
CMCI from the memory controller reporting an uncorrected error with a
UCNA signature, and the core reporting and SRAR signature machine check
when the data is about to be consumed.

If the CMCI wins that race, the page is marked poisoned when
uc_decode_notifier() calls memory_failure() and the machine check
processing code finds the page already poisoned.  It calls
kill_accessing_process() to make sure a SIGBUS is sent.  But returns the
wrong error code.

Console log looks like this:

  mce: Uncorrected hardware memory error in user-access at 3710b3400
  Memory failure: 0x3710b3: recovery action for dirty LRU page: Recovered
  Memory failure: 0x3710b3: already hardware poisoned
  Memory failure: 0x3710b3: Sending SIGBUS to einj_mem_uc:361438 due to hardware memory corruption
  mce: Memory error not recovered

kill_accessing_process() is supposed to return -EHWPOISON to notify that
SIGBUS is already set to the process and kill_me_maybe() doesn't have to
send it again.  But current code simply fails to do this, so fix it to
make sure to work as intended.  This change avoids the noise message
"Memory error not recovered" and skips duplicate SIGBUSs.

[tony.luck@intel.com: reword some parts of commit message]

Link: https://lkml.kernel.org/r/20220113231117.1021405-1-naoya.horiguchi@linux.dev
Fixes: a3f5d80ea401 ("mm,hwpoison: send SIGBUS with error virutal address")
Signed-off-by: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Reported-by: Youquan Song &lt;youquan.song@intel.com&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mm/memory-failure.c: skip huge_zero_page in memory_failure()</title>
<updated>2022-04-27T12:41:11+00:00</updated>
<author>
<name>Xu Yu</name>
<email>xuyu@linux.alibaba.com</email>
</author>
<published>2022-04-21T23:35:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9bf52fe6a1d7ff1e58b0ed1caa9715ef4ac5f5d1'/>
<id>urn:sha1:9bf52fe6a1d7ff1e58b0ed1caa9715ef4ac5f5d1</id>
<content type='text'>
commit d173d5417fb67411e623d394aab986d847e47dad upstream.

Kernel panic when injecting memory_failure for the global
huge_zero_page, when CONFIG_DEBUG_VM is enabled, as follows.

  Injecting memory failure for pfn 0x109ff9 at process virtual address 0x20ff9000
  page:00000000fb053fc3 refcount:2 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x109e00
  head:00000000fb053fc3 order:9 compound_mapcount:0 compound_pincount:0
  flags: 0x17fffc000010001(locked|head|node=0|zone=2|lastcpupid=0x1ffff)
  raw: 017fffc000010001 0000000000000000 dead000000000122 0000000000000000
  raw: 0000000000000000 0000000000000000 00000002ffffffff 0000000000000000
  page dumped because: VM_BUG_ON_PAGE(is_huge_zero_page(head))
  ------------[ cut here ]------------
  kernel BUG at mm/huge_memory.c:2499!
  invalid opcode: 0000 [#1] PREEMPT SMP PTI
  CPU: 6 PID: 553 Comm: split_bug Not tainted 5.18.0-rc1+ #11
  Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 3288b3c 04/01/2014
  RIP: 0010:split_huge_page_to_list+0x66a/0x880
  Code: 84 9b fb ff ff 48 8b 7c 24 08 31 f6 e8 9f 5d 2a 00 b8 b8 02 00 00 e9 e8 fb ff ff 48 c7 c6 e8 47 3c 82 4c b
  RSP: 0018:ffffc90000dcbdf8 EFLAGS: 00010246
  RAX: 000000000000003c RBX: 0000000000000001 RCX: 0000000000000000
  RDX: 0000000000000000 RSI: ffffffff823e4c4f RDI: 00000000ffffffff
  RBP: ffff88843fffdb40 R08: 0000000000000000 R09: 00000000fffeffff
  R10: ffffc90000dcbc48 R11: ffffffff82d68448 R12: ffffea0004278000
  R13: ffffffff823c6203 R14: 0000000000109ff9 R15: ffffea000427fe40
  FS:  00007fc375a26740(0000) GS:ffff88842fd80000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007fc3757c9290 CR3: 0000000102174006 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   try_to_split_thp_page+0x3a/0x130
   memory_failure+0x128/0x800
   madvise_inject_error.cold+0x8b/0xa1
   __x64_sys_madvise+0x54/0x60
   do_syscall_64+0x35/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xae
  RIP: 0033:0x7fc3754f8bf9
  Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 8
  RSP: 002b:00007ffeda93a1d8 EFLAGS: 00000217 ORIG_RAX: 000000000000001c
  RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc3754f8bf9
  RDX: 0000000000000064 RSI: 0000000000003000 RDI: 0000000020ff9000
  RBP: 00007ffeda93a200 R08: 0000000000000000 R09: 0000000000000000
  R10: 00000000ffffffff R11: 0000000000000217 R12: 0000000000400490
  R13: 00007ffeda93a2e0 R14: 0000000000000000 R15: 0000000000000000

This makes huge_zero_page bail out explicitly before split in
memory_failure(), thus the panic above won't happen again.

Link: https://lkml.kernel.org/r/497d3835612610e370c74e697ea3c721d1d55b9c.1649775850.git.xuyu@linux.alibaba.com
Fixes: 6a46079cf57a ("HWPOISON: The high level memory error handler in the VM v7")
Signed-off-by: Xu Yu &lt;xuyu@linux.alibaba.com&gt;
Reported-by: Abaci &lt;abaci@linux.alibaba.com&gt;
Suggested-by: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Acked-by: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Reviewed-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>memory-failure: fetch compound_head after pgmap_pfn_valid()</title>
<updated>2022-01-30T07:56:58+00:00</updated>
<author>
<name>Joao Martins</name>
<email>joao.m.martins@oracle.com</email>
</author>
<published>2022-01-29T21:41:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=61e28cf0543c7d8e6ef88c3c305f727c5a21ba5b'/>
<id>urn:sha1:61e28cf0543c7d8e6ef88c3c305f727c5a21ba5b</id>
<content type='text'>
memory_failure_dev_pagemap() at the moment assumes base pages (e.g.
dax_lock_page()).  For devmap with compound pages fetch the
compound_head in case a tail page memory failure is being handled.

Currently this is a nop, but in the advent of compound pages in
dev_pagemap it allows memory_failure_dev_pagemap() to keep working.

Without this fix memory-failure handling (i.e.  MCEs on pmem) with
device-dax configured namespaces will regress (and crash).

Link: https://lkml.kernel.org/r/20211202204422.26777-2-joao.m.martins@oracle.com
Reported-by: Jane Chu &lt;jane.chu@oracle.com&gt;
Signed-off-by: Joao Martins &lt;joao.m.martins@oracle.com&gt;
Reviewed-by: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Reviewed-by: Dan Williams &lt;dan.j.williams@intel.com&gt;
Reviewed-by: Muchun Song &lt;songmuchun@bytedance.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge branch 'akpm' (patches from Andrew)</title>
<updated>2022-01-15T18:37:06+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-01-15T18:37:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f56caedaf94f9ced5dbfcdb0060a3e788d2078af'/>
<id>urn:sha1:f56caedaf94f9ced5dbfcdb0060a3e788d2078af</id>
<content type='text'>
Merge misc updates from Andrew Morton:
 "146 patches.

  Subsystems affected by this patch series: kthread, ia64, scripts,
  ntfs, squashfs, ocfs2, vfs, and mm (slab-generic, slab, kmemleak,
  dax, kasan, debug, pagecache, gup, shmem, frontswap, memremap,
  memcg, selftests, pagemap, dma, vmalloc, memory-failure, hugetlb,
  userfaultfd, vmscan, mempolicy, oom-kill, hugetlbfs, migration, thp,
  ksm, page-poison, percpu, rmap, zswap, zram, cleanups, hmm, and
  damon)"

* emailed patches from Andrew Morton &lt;akpm@linux-foundation.org&gt;: (146 commits)
  mm/damon: hide kernel pointer from tracepoint event
  mm/damon/vaddr: hide kernel pointer from damon_va_three_regions() failure log
  mm/damon/vaddr: use pr_debug() for damon_va_three_regions() failure logging
  mm/damon/dbgfs: remove an unnecessary variable
  mm/damon: move the implementation of damon_insert_region to damon.h
  mm/damon: add access checking for hugetlb pages
  Docs/admin-guide/mm/damon/usage: update for schemes statistics
  mm/damon/dbgfs: support all DAMOS stats
  Docs/admin-guide/mm/damon/reclaim: document statistics parameters
  mm/damon/reclaim: provide reclamation statistics
  mm/damon/schemes: account how many times quota limit has exceeded
  mm/damon/schemes: account scheme actions that successfully applied
  mm/damon: remove a mistakenly added comment for a future feature
  Docs/admin-guide/mm/damon/usage: update for kdamond_pid and (mk|rm)_contexts
  Docs/admin-guide/mm/damon/usage: mention tracepoint at the beginning
  Docs/admin-guide/mm/damon/usage: remove redundant information
  Docs/admin-guide/mm/damon/usage: update for scheme quotas and watermarks
  mm/damon: convert macro functions to static inline functions
  mm/damon: modify damon_rand() macro to static inline function
  mm/damon: move damon_rand() definition into damon.h
  ...
</content>
</entry>
<entry>
<title>mm: fix some comment errors</title>
<updated>2022-01-15T14:30:31+00:00</updated>
<author>
<name>Quanfa Fu</name>
<email>fuqf0919@gmail.com</email>
</author>
<published>2022-01-14T22:09:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0b8f0d870020dbd7037bfacbb73a9b3213470f90'/>
<id>urn:sha1:0b8f0d870020dbd7037bfacbb73a9b3213470f90</id>
<content type='text'>
Link: https://lkml.kernel.org/r/20211101040208.460810-1-fuqf0919@gmail.com
Signed-off-by: Quanfa Fu &lt;fuqf0919@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm/hwpoison: fix unpoison_memory()</title>
<updated>2022-01-15T14:30:31+00:00</updated>
<author>
<name>Naoya Horiguchi</name>
<email>naoya.horiguchi@nec.com</email>
</author>
<published>2022-01-14T22:09:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bf181c582588f8f7406d52f2ee228539b465f173'/>
<id>urn:sha1:bf181c582588f8f7406d52f2ee228539b465f173</id>
<content type='text'>
After recent soft-offline rework, error pages can be taken off from
buddy allocator, but the existing unpoison_memory() does not properly
undo the operation.  Moreover, due to the recent change on
__get_hwpoison_page(), get_page_unless_zero() is hardly called for
hwpoisoned pages.  So __get_hwpoison_page() highly likely returns -EBUSY
(meaning to fail to grab page refcount) and unpoison just clears
PG_hwpoison without releasing a refcount.  That does not lead to a
critical issue like kernel panic, but unpoisoned pages never get back to
buddy (leaked permanently), which is not good.

To (partially) fix this, we need to identify "taken off" pages from
other types of hwpoisoned pages.  We can't use refcount or page flags
for this purpose, so a pseudo flag is defined by hacking -&gt;private
field.  Someone might think that put_page() is enough to cancel
taken-off pages, but the normal free path contains some operations not
suitable for the current purpose, and can fire VM_BUG_ON().

Note that unpoison_memory() is now supposed to be cancel hwpoison events
injected only by madvise() or
/sys/devices/system/memory/{hard,soft}_offline_page, not by MCE
injection, so please don't try to use unpoison when testing with MCE
injection.

[lkp@intel.com: report build failure for ARCH=i386]

Link: https://lkml.kernel.org/r/20211115084006.3728254-4-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Reviewed-by: Yang Shi &lt;shy828301@gmail.com&gt;
Cc: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Ding Hui &lt;dinghui@sangfor.com.cn&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: "Aneesh Kumar K.V" &lt;aneesh.kumar@linux.vnet.ibm.com&gt;
Cc: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm/hwpoison: remove MF_MSG_BUDDY_2ND and MF_MSG_POISONED_HUGE</title>
<updated>2022-01-15T14:30:31+00:00</updated>
<author>
<name>Naoya Horiguchi</name>
<email>naoya.horiguchi@nec.com</email>
</author>
<published>2022-01-14T22:09:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c9fdc4d5487a16bd1f003fc8b66e91f88efb50e6'/>
<id>urn:sha1:c9fdc4d5487a16bd1f003fc8b66e91f88efb50e6</id>
<content type='text'>
These action_page_types are no longer used, so remove them.

Link: https://lkml.kernel.org/r/20211115084006.3728254-3-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Acked-by: Yang Shi &lt;shy828301@gmail.com&gt;
Cc: "Aneesh Kumar K.V" &lt;aneesh.kumar@linux.vnet.ibm.com&gt;
Cc: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Ding Hui &lt;dinghui@sangfor.com.cn&gt;
Cc: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm/hwpoison: mf_mutex for soft offline and unpoison</title>
<updated>2022-01-15T14:30:31+00:00</updated>
<author>
<name>Naoya Horiguchi</name>
<email>naoya.horiguchi@nec.com</email>
</author>
<published>2022-01-14T22:09:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=91d005479e06392617bacc114509d611b705eaac'/>
<id>urn:sha1:91d005479e06392617bacc114509d611b705eaac</id>
<content type='text'>
Patch series "mm/hwpoison: fix unpoison_memory()", v4.

The main purpose of this series is to sync unpoison code to recent
changes around how hwpoison code takes page refcount.  Unpoison should
work or simply fail (without crash) if impossible.

The recent works of keeping hwpoison pages in shmem pagecache introduce
a new state of hwpoisoned pages, but unpoison for such pages is not
supported yet with this series.

It seems that soft-offline and unpoison can be used as general purpose
page offline/online mechanism (not in the context of memory error).  I
think that we need some additional works to realize it because currently
soft-offline and unpoison are assumed not to happen so frequently (print
out too many messages for aggressive usecases).  But anyway this could
be another interesting next topic.

v1: https://lore.kernel.org/linux-mm/20210614021212.223326-1-nao.horiguchi@gmail.com/
v2: https://lore.kernel.org/linux-mm/20211025230503.2650970-1-naoya.horiguchi@linux.dev/
v3: https://lore.kernel.org/linux-mm/20211105055058.3152564-1-naoya.horiguchi@linux.dev/

This patch (of 3):

Originally mf_mutex is introduced to serialize multiple MCE events, but
it is not that useful to allow unpoison to run in parallel with
memory_failure() and soft offline.  So apply mf_mutex to soft offline
and unpoison.  The memory failure handler and soft offline handler get
simpler with this.

Link: https://lkml.kernel.org/r/20211115084006.3728254-1-naoya.horiguchi@linux.dev
Link: https://lkml.kernel.org/r/20211115084006.3728254-2-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Reviewed-by: Yang Shi &lt;shy828301@gmail.com&gt;
Cc: "Aneesh Kumar K.V" &lt;aneesh.kumar@linux.vnet.ibm.com&gt;
Cc: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Ding Hui &lt;dinghui@sangfor.com.cn&gt;
Cc: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
</feed>
