The patch titled
Subject: mm/memory-failure.c: fix race with changing page compound again
has been removed from the -mm tree. Its filename was
mm-memory-failurec-fix-race-with-changing-page-compound-again.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: 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@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>
---
include/linux/mm.h | 1 +
include/ras/ras_event.h | 1 +
mm/memory-failure.c | 12 ++++++++++++
3 files changed, 14 insertions(+)
--- a/include/linux/mm.h~mm-memory-failurec-fix-race-with-changing-page-compound-again
+++ a/include/linux/mm.h
@@ -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,
};
--- a/include/ras/ras_event.h~mm-memory-failurec-fix-race-with-changing-page-compound-again
+++ a/include/ras/ras_event.h
@@ -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" )
/*
--- a/mm/memory-failure.c~mm-memory-failurec-fix-race-with-changing-page-compound-again
+++ a/mm/memory-failure.c
@@ -732,6 +732,7 @@ static const char * const action_page_ty
[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(unsign
}
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)) {
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-huge_memory-make-is_transparent_hugepage-static.patch
