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mm/memory-failure.c: fix race with changing page compound again

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Patch series "A few fixup patches for memory failure", v2.

This series contains a few patches to fix the race with changing page
compound page, make non-LRU movable pages unhandlable and so on.  More
details can be found in the respective changelogs.

There is a race window where we got the compound_head, the hugetlb page
could be freed to buddy, or even changed to another compound page just
before we try to get hwpoison page.  Think about the below race window:

  CPU 1					  CPU 2
  memory_failure_hugetlb
  struct page *head = compound_head(p);
					  hugetlb page might be freed to
					  buddy, or even changed to another
					  compound page.

  get_hwpoison_page -- page is not what we want now...

If this race happens, just bail out.  Also MF_MSG_DIFFERENT_PAGE_SIZE is
introduced to record this event.

[akpm@linux-foundation.org: s@/**@/*@, per Naoya Horiguchi]

Link: https://lkml.kernel.org/r/20220312074613.4798-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220312074613.4798-2-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2022-03-22 14:44:44 -07:00 committed by Linus Torvalds
parent a06ad3c0c7
commit 888af2701d
3 changed files with 14 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
include/linux/mm.h
View file

@ -3239,6 +3239,7 @@ enum mf_action_page_type {
MF_MSG_BUDDY, MF_MSG_BUDDY,
MF_MSG_DAX, MF_MSG_DAX,
MF_MSG_UNSPLIT_THP, MF_MSG_UNSPLIT_THP,
MF_MSG_DIFFERENT_PAGE_SIZE,
MF_MSG_UNKNOWN, MF_MSG_UNKNOWN,
}; };

1
include/ras/ras_event.h
View file

@ -374,6 +374,7 @@ TRACE_EVENT(aer_event,
EM ( MF_MSG_BUDDY, "free buddy page" ) \ EM ( MF_MSG_BUDDY, "free buddy page" ) \
EM ( MF_MSG_DAX, "dax page" ) \ EM ( MF_MSG_DAX, "dax page" ) \
EM ( MF_MSG_UNSPLIT_THP, "unsplit thp" ) \ EM ( MF_MSG_UNSPLIT_THP, "unsplit thp" ) \
EM ( MF_MSG_DIFFERENT_PAGE_SIZE, "different page size" ) \
EMe ( MF_MSG_UNKNOWN, "unknown page" ) EMe ( MF_MSG_UNKNOWN, "unknown page" )
/* /*

12
mm/memory-failure.c
View file

@ -732,6 +732,7 @@ static const char * const action_page_types[] = {
[MF_MSG_BUDDY] = "free buddy page", [MF_MSG_BUDDY] = "free buddy page",
[MF_MSG_DAX] = "dax page", [MF_MSG_DAX] = "dax page",
[MF_MSG_UNSPLIT_THP] = "unsplit thp", [MF_MSG_UNSPLIT_THP] = "unsplit thp",
[MF_MSG_DIFFERENT_PAGE_SIZE] = "different page size",
[MF_MSG_UNKNOWN] = "unknown page", [MF_MSG_UNKNOWN] = "unknown page",
}; };
@ -1532,6 +1533,17 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags)
} }
lock_page(head); lock_page(head);
/*
* The page could have changed compound pages due to race window.
* If this happens just bail out.
*/
if (!PageHuge(p) || compound_head(p) != head) {
action_result(pfn, MF_MSG_DIFFERENT_PAGE_SIZE, MF_IGNORED);
res = -EBUSY;
goto out;
}
page_flags = head->flags; page_flags = head->flags;
if (hwpoison_filter(p)) { if (hwpoison_filter(p)) {