The patch titled
Subject: mm/thp: do not wait for lock_page() in deferred_split_scan()
has been added to the -mm tree. Its filename is
mm-thp-do-not-wait-for-lock_page-in-deferred_split_scan.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-do-not-wait-for-lock_page-in-deferred_split_scan.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-do-not-wait-for-lock_page-in-deferred_split_scan.patch
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------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: mm/thp: do not wait for lock_page() in deferred_split_scan()
deferred_split_scan() gets called from reclaim path. Waiting for page
lock may lead to deadlock there.
Replace lock_page() with trylock_page() and skip the page if we failed to
lock it. We will get to the page on the next scan.
Link: http://lkml.kernel.org/r/20180315150747.31945-1-kirill.shutemov@xxxxxxxxxxxxxxx
Fixes: 9a982250f773 ("thp: introduce deferred_split_huge_page()")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN mm/huge_memory.c~mm-thp-do-not-wait-for-lock_page-in-deferred_split_scan mm/huge_memory.c
--- a/mm/huge_memory.c~mm-thp-do-not-wait-for-lock_page-in-deferred_split_scan
+++ a/mm/huge_memory.c
@@ -2783,11 +2783,13 @@ static unsigned long deferred_split_scan
list_for_each_safe(pos, next, &list) {
page = list_entry((void *)pos, struct page, mapping);
- lock_page(page);
+ if (!trylock_page(page))
+ goto next;
/* split_huge_page() removes page from list on success */
if (!split_huge_page(page))
split++;
unlock_page(page);
+next:
put_page(page);
}
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
mm-khugepaged-convert-vm_bug_on-to-collapse-fail.patch
mm-thp-do-not-wait-for-lock_page-in-deferred_split_scan.patch