pve-kernel-lowlatency-qoup/patches/kernel/0007-mm-thp-Do-not-wait-for-lock_page-in-deferred_split_s.patch
Fabian Grünbichler 8e89f13c59 fix #1633: potential deadlock with THPs
see https://marc.info/?l=linux-mm&m=151683828707588

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
2018-03-27 16:02:05 +02:00

47 lines
1.5 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Thu, 15 Mar 2018 18:07:47 +0300
Subject: [PATCH] mm/thp: Do not wait for lock_page() in deferred_split_scan()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
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.
Fixes: 9a982250f773 ("thp: introduce deferred_split_huge_page()")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
(cherry-picked from https://patchwork.kernel.org/patch/10284703/)
Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---
mm/huge_memory.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 0e7ded98d114..4ed6c89e95c3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2791,11 +2791,13 @@ static unsigned long deferred_split_scan(struct shrinker *shrink,
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);
}
--
2.14.2