The patch titled
Subject: memcg: fix use_hierarchy css_is_ancestor oops regression
has been added to the -mm tree. Its filename is
memcg-fix-use_hierarchy-css_is_ancestor-oops-regression.patch
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From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: memcg: fix use_hierarchy css_is_ancestor oops regression
If use_hierarchy is set, reclaim testing soon oopses in css_is_ancestor()
called from __mem_cgroup_same_or_subtree() called from page_referenced():
when processes are exiting, it's easy for mm_match_cgroup() to pass along
a NULL memcg coming from a NULL mm->owner.
Check for that in __mem_cgroup_same_or_subtree(). Return true or false?
False because we cannot know if it was in the hierarchy, but also false
because it's better not to count a reference from an exiting process.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/memcontrol.c~memcg-fix-use_hierarchy-css_is_ancestor-oops-regression mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-fix-use_hierarchy-css_is_ancestor-oops-regression
+++ a/mm/memcontrol.c
@@ -1148,7 +1148,7 @@ bool __mem_cgroup_same_or_subtree(const
{
if (root_memcg == memcg)
return true;
- if (!root_memcg->use_hierarchy)
+ if (!root_memcg->use_hierarchy || !memcg)
return false;
return css_is_ancestor(&memcg->css, &root_memcg->css);
}
_
Subject: Subject: memcg: fix use_hierarchy css_is_ancestor oops regression
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
linux-next.patch
thp-avoid-atomic64_read-in-pmd_read_atomic-for-32bit-pae.patch
memcg-fix-use_hierarchy-css_is_ancestor-oops-regression.patch
tmpfs-implement-numa-node-interleaving.patch
tmpfs-implement-numa-node-interleaving-fix.patch
memcg-rename-mem_cgroup_stat_swapout-as-mem_cgroup_stat_swap.patch
memcg-remove-mem_cgroup_charge_type_force.patch
documentation-update-how-page-cluster-affects-swap-i-o.patch
mm-compaction-handle-incorrect-migrate_unmovable-type-pageblocks.patch
mm-compaction-handle-incorrect-migrate_unmovable-type-pageblocks-fix-2.patch
prio_tree-debugging-patch.patch
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