summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorVladimir Davydov <vdavydov@parallels.com>2015-05-14 15:16:58 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-06-06 08:21:05 -0700
commite54fa19a36291ea803f9b0b1caba1f2b7a726391 (patch)
tree668af271e39c19170ae6a07b669d9a5d8874a53a
parent4d039741b4155da5b25bc484b32439794672645f (diff)
kernfs: do not account ino_ida allocations to memcg
commit 499611ed451508a42d1d7d1faff10177827755d5 upstream. root->ino_ida is used for kernfs inode number allocations. Since IDA has a layered structure, different IDs can reside on the same layer, which is currently accounted to some memory cgroup. The problem is that each kmem cache of a memory cgroup has its own directory on sysfs (under /sys/fs/kernel/<cache-name>/cgroup). If the inode number of such a directory or any file in it gets allocated from a layer accounted to the cgroup which the cache is created for, the cgroup will get pinned for good, because one has to free all kmem allocations accounted to a cgroup in order to release it and destroy all its kmem caches. That said we must not account layers of ino_ida to any memory cgroup. Since per net init operations may create new sysfs entries directly (e.g. lo device) or indirectly (nf_conntrack creates a new kmem cache per each namespace, which, in turn, creates new sysfs entries), an easy way to reproduce this issue is by creating network namespace(s) from inside a kmem-active memory cgroup. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Greg Thelen <gthelen@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/kernfs/dir.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 6acc964..345b35f 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -518,7 +518,14 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
if (!kn)
goto err_out1;
- ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL);
+ /*
+ * If the ino of the sysfs entry created for a kmem cache gets
+ * allocated from an ida layer, which is accounted to the memcg that
+ * owns the cache, the memcg will get pinned forever. So do not account
+ * ino ida allocations.
+ */
+ ret = ida_simple_get(&root->ino_ida, 1, 0,
+ GFP_KERNEL | __GFP_NOACCOUNT);
if (ret < 0)
goto err_out2;
kn->ino = ret;