This is a note to let you know that I've just added the patch titled
mm/memory-failure.c: fix race with changing page compound again
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-memory-failure.c-fix-race-with-changing-page-comp.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b4e44dfaac719d6981fdb1c6a0089279e142bc41
Author: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Date: Tue Mar 22 14:44:44 2022 -0700
mm/memory-failure.c: fix race with changing page compound again
[ Upstream commit 888af2701db79b9b27c7e37f9ede528a5ca53b76 ]
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@xxxxxxxxxxxxxxxxxxxx: s@/**@/*@, per Naoya Horiguchi]
Link: https://lkml.kernel.org/r/20220312074613.4798-1-linmiaohe@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20220312074613.4798-2-linmiaohe@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Acked-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 85205adcdd0d..7a80a08eec84 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3167,6 +3167,7 @@ enum mf_action_page_type {
MF_MSG_BUDDY_2ND,
MF_MSG_DAX,
MF_MSG_UNSPLIT_THP,
+ MF_MSG_DIFFERENT_PAGE_SIZE,
MF_MSG_UNKNOWN,
};
diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h
index 0bdbc0d17d2f..cac13ff1d6eb 100644
--- a/include/ras/ras_event.h
+++ b/include/ras/ras_event.h
@@ -376,6 +376,7 @@ TRACE_EVENT(aer_event,
EM ( MF_MSG_BUDDY_2ND, "free buddy page (2nd try)" ) \
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" )
/*
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5664bafd5e77..a4d70c21c146 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -741,6 +741,7 @@ static const char * const action_page_types[] = {
[MF_MSG_BUDDY_2ND] = "free buddy page (2nd try)",
[MF_MSG_DAX] = "dax page",
[MF_MSG_UNSPLIT_THP] = "unsplit thp",
+ [MF_MSG_DIFFERENT_PAGE_SIZE] = "different page size",
[MF_MSG_UNKNOWN] = "unknown page",
};
@@ -1461,6 +1462,17 @@ 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;
/*
