The patch titled
Subject: kernfs: do not account ino_ida allocations to memcg
has been removed from the -mm tree. Its filename was
kernfs-do-not-account-ino_ida-allocations-to-memcg.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Vladimir Davydov <[email protected]>
Subject: kernfs: do not account ino_ida allocations to memcg
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 <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Greg Thelen <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: <[email protected]> [4.0.x]
Signed-off-by: Andrew Morton <[email protected]>
---
fs/kernfs/dir.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff -puN fs/kernfs/dir.c~kernfs-do-not-account-ino_ida-allocations-to-memcg
fs/kernfs/dir.c
--- a/fs/kernfs/dir.c~kernfs-do-not-account-ino_ida-allocations-to-memcg
+++ a/fs/kernfs/dir.c
@@ -518,7 +518,14 @@ static struct kernfs_node *__kernfs_new_
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;
_
Patches currently in -mm which might be from [email protected] are
rmap-fix-theoretical-race-between-do_wp_page-and-shrink_active_list.patch
rmap-fix-theoretical-race-between-do_wp_page-and-shrink_active_list-fix.patch
rmap-fix-theoretical-race-between-do_wp_page-and-shrink_active_list-fix-fix.patch
mm-vmscan-fix-the-page-state-calculation-in-too_many_isolated.patch
linux-next.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
