This is a note to let you know that I've just added the patch titled
memcg, shmem: fix shmem migration to use lrucare
to the 3.18-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:
memcg-shmem-fix-shmem-migration-to-use-lrucare.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f5e03a4989e80a86f8b514659dca8539132e6e09 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@xxxxxxx>
Date: Thu, 5 Feb 2015 12:25:14 -0800
Subject: memcg, shmem: fix shmem migration to use lrucare
From: Michal Hocko <mhocko@xxxxxxx>
commit f5e03a4989e80a86f8b514659dca8539132e6e09 upstream.
It has been reported that 965GM might trigger
VM_BUG_ON_PAGE(!lrucare && PageLRU(oldpage), oldpage)
in mem_cgroup_migrate when shmem wants to replace a swap cache page
because of shmem_should_replace_page (the page is allocated from an
inappropriate zone). shmem_replace_page expects that the oldpage is not
on LRU list and calls mem_cgroup_migrate without lrucare. This is
obviously incorrect because swapcache pages might be on the LRU list
(e.g. swapin readahead page).
Fix this by enabling lrucare for the migration in shmem_replace_page.
Also clarify that lrucare should be used even if one of the pages might
be on LRU list.
The BUG_ON will trigger only when CONFIG_DEBUG_VM is enabled but even
without that the migration code might leave the old page on an
inappropriate memcg' LRU which is not that critical because the page
would get removed with its last reference but it is still confusing.
Fixes: 0a31bc97c80c ("mm: memcontrol: rewrite uncharge API")
Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
Reported-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reported-by: Dave Airlie <airlied@xxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 2 +-
mm/shmem.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6589,7 +6589,7 @@ void mem_cgroup_uncharge_list(struct lis
* mem_cgroup_migrate - migrate a charge to another page
* @oldpage: currently charged page
* @newpage: page to transfer the charge to
- * @lrucare: both pages might be on the LRU already
+ * @lrucare: either or both pages might be on the LRU already
*
* Migrate the charge from @oldpage to @newpage.
*
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1013,7 +1013,7 @@ static int shmem_replace_page(struct pag
*/
oldpage = newpage;
} else {
- mem_cgroup_migrate(oldpage, newpage, false);
+ mem_cgroup_migrate(oldpage, newpage, true);
lru_cache_add_anon(newpage);
*pagep = newpage;
}
Patches currently in stable-queue which might be from mhocko@xxxxxxx are
queue-3.18/memcg-shmem-fix-shmem-migration-to-use-lrucare.patch
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