This is a note to let you know that I've just added the patch titled
mm/thp: do not wait for lock_page() in deferred_split_scan()
to the 4.9-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-thp-do-not-wait-for-lock_page-in-deferred_split_scan.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fa41b900c30b45fab03783724932dc30cd46a6be Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Date: Thu, 22 Mar 2018 16:17:31 -0700
Subject: mm/thp: do not wait for lock_page() in deferred_split_scan()
From: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
commit fa41b900c30b45fab03783724932dc30cd46a6be upstream.
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>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2279,11 +2279,13 @@ 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 stable-queue which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
queue-4.9/mm-khugepaged.c-convert-vm_bug_on-to-collapse-fail.patch
queue-4.9/mm-thp-do-not-wait-for-lock_page-in-deferred_split_scan.patch
queue-4.9/mm-shmem-do-not-wait-for-lock_page-in-shmem_unused_huge_shrink.patch