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authorYang Shi <shy828301@gmail.com>2021-10-29 00:36:11 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-10-29 03:18:55 +0300
commiteac96c3efdb593df1a57bb5b95dbe037bfa9a522 (patch)
treec24408ca87d4c74b41d3a05e55d337b3af528b6f /mm/huge_memory.c
parentc7cb42e94473aafe553c0f2a3d8ca904599399ed (diff)
downloadlinux-eac96c3efdb593df1a57bb5b95dbe037bfa9a522.tar.xz
mm: filemap: check if THP has hwpoisoned subpage for PMD page fault
When handling shmem page fault the THP with corrupted subpage could be PMD mapped if certain conditions are satisfied. But kernel is supposed to send SIGBUS when trying to map hwpoisoned page. There are two paths which may do PMD map: fault around and regular fault. Before commit f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault() codepaths") the thing was even worse in fault around path. The THP could be PMD mapped as long as the VMA fits regardless what subpage is accessed and corrupted. After this commit as long as head page is not corrupted the THP could be PMD mapped. In the regular fault path the THP could be PMD mapped as long as the corrupted page is not accessed and the VMA fits. This loophole could be fixed by iterating every subpage to check if any of them is hwpoisoned or not, but it is somewhat costly in page fault path. So introduce a new page flag called HasHWPoisoned on the first tail page. It indicates the THP has hwpoisoned subpage(s). It is set if any subpage of THP is found hwpoisoned by memory failure and after the refcount is bumped successfully, then cleared when the THP is freed or split. The soft offline path doesn't need this since soft offline handler just marks a subpage hwpoisoned when the subpage is migrated successfully. But shmem THP didn't get split then migrated at all. Link: https://lkml.kernel.org/r/20211020210755.23964-3-shy828301@gmail.com Fixes: 800d8c63b2e9 ("shmem: add huge pages support") Signed-off-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 92192cb086c7..c5142d237e48 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2426,6 +2426,8 @@ static void __split_huge_page(struct page *page, struct list_head *list,
/* lock lru list/PageCompound, ref frozen by page_ref_freeze */
lruvec = lock_page_lruvec(head);
+ ClearPageHasHWPoisoned(head);
+
for (i = nr - 1; i >= 1; i--) {
__split_huge_page_tail(head, i, lruvec, list);
/* Some pages can be beyond EOF: drop them from page cache */