The patch titled
memcg: fix a race when setting memory.swappiness
has been removed from the -mm tree. Its filename was
memcg-fix-a-race-when-setting-memoryswappiness.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: memcg: fix a race when setting memory.swappiness
From: Li Zefan <lizf@xxxxxxxxxxxxxx>
(suppose: memcg->use_hierarchy == 0 and memcg->swappiness == 60)
echo 10 > /memcg/0/swappiness |
mem_cgroup_swappiness_write() |
... | echo 1 > /memcg/0/use_hierarchy
| mkdir /mnt/0/1
| sub_memcg->swappiness = 60;
memcg->swappiness = 10; |
In the above scenario, we end up having 2 different swappiness
values in a single hierarchy.
We should hold cgroup_lock() when cheking cgrp->children list.
Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Cc: Paul Menage <menage@xxxxxxxxxx>
Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff -puN mm/memcontrol.c~memcg-fix-a-race-when-setting-memoryswappiness mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-fix-a-race-when-setting-memoryswappiness
+++ a/mm/memcontrol.c
@@ -1992,6 +1992,7 @@ static int mem_cgroup_swappiness_write(s
{
struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
struct mem_cgroup *parent;
+
if (val > 100)
return -EINVAL;
@@ -1999,15 +2000,22 @@ static int mem_cgroup_swappiness_write(s
return -EINVAL;
parent = mem_cgroup_from_cont(cgrp->parent);
+
+ cgroup_lock();
+
/* If under hierarchy, only empty-root can set this value */
if ((parent->use_hierarchy) ||
- (memcg->use_hierarchy && !list_empty(&cgrp->children)))
+ (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
+ cgroup_unlock();
return -EINVAL;
+ }
spin_lock(&memcg->reclaim_param_lock);
memcg->swappiness = val;
spin_unlock(&memcg->reclaim_param_lock);
+ cgroup_unlock();
+
return 0;
}
_
Patches currently in -mm which might be from lizf@xxxxxxxxxxxxxx are
origin.patch
memcg-get-put-parents-at-create-free.patch
linux-next.patch
relax-ns_can_attach-checks-to-allow-attaching-to-grandchild-cgroups.patch
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