Commit 888af270 authored by Miaohe Lin's avatar Miaohe Lin Committed by Linus Torvalds
Browse files

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

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: default avatarMiaohe Lin <linmiaohe@huawei.com>
Acked-by: default avatarNaoya 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a06ad3c0

include/linux/mm.h

+1 −0
Original line number Diff line number Diff line
@@ -3239,6 +3239,7 @@ enum mf_action_page_type { 
	MF_MSG_BUDDY,

	MF_MSG_DAX,

	MF_MSG_UNSPLIT_THP,

	MF_MSG_DIFFERENT_PAGE_SIZE,

	MF_MSG_UNKNOWN,

};

include/ras/ras_event.h

+1 −0
Original line number Diff line number Diff line
@@ -374,6 +374,7 @@ TRACE_EVENT(aer_event, 
	EM ( MF_MSG_BUDDY, "free buddy page" )				\

	EM ( MF_MSG_DAX, "dax page" )					\

	EM ( MF_MSG_UNSPLIT_THP, "unsplit thp" )			\

	EM ( MF_MSG_DIFFERENT_PAGE_SIZE, "different page size" )	\

	EMe ( MF_MSG_UNKNOWN, "unknown page" )



/*

mm/memory-failure.c

+12 −0
Original line number Diff line number Diff line
@@ -732,6 +732,7 @@ static const char * const action_page_types[] = { 
	[MF_MSG_BUDDY]			= "free buddy page",

	[MF_MSG_DAX]			= "dax page",

	[MF_MSG_UNSPLIT_THP]		= "unsplit thp",

	[MF_MSG_DIFFERENT_PAGE_SIZE]	= "different page size",

	[MF_MSG_UNKNOWN]		= "unknown page",

};
@@ -1532,6 +1533,17 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags) 
	}



	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;



	if (hwpoison_filter(p)) {