Subject: [merged] memcg-fix-endless-loop-in-__mem_cgroup_iter_next.patch 
removed from -mm tree
To: 
[email protected],[email protected],[email protected],[email protected],[email protected],[email protected]
From: [email protected]
Date: Thu, 06 Mar 2014 12:37:30 -0800


The patch titled
     Subject: memcg: fix endless loop in __mem_cgroup_iter_next()
has been removed from the -mm tree.  Its filename was
     memcg-fix-endless-loop-in-__mem_cgroup_iter_next.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Hugh Dickins <[email protected]>
Subject: memcg: fix endless loop in __mem_cgroup_iter_next()

0eef615665ed ("memcg: fix css reference leak and endless loop in
mem_cgroup_iter") got the interaction with the commit a few before it
d8ad30559715 ("mm/memcg: iteration skip memcgs not yet fully initialized")
slightly wrong, and we didn't notice at the time.

It's elusive, and harder to get than the original, but for a couple of
days before rc1, I several times saw a endless loop similar to that
supposedly being fixed.

This time it was a tighter loop in __mem_cgroup_iter_next(): because we
can get here when our root has already been offlined, and the ordering of
conditions was such that we then just cycled around forever.

Fixes: 0eef615665ed ("memcg: fix css reference leak and endless loop in 
mem_cgroup_iter").
Signed-off-by: Hugh Dickins <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Greg Thelen <[email protected]>
Cc: <[email protected]>    [3.12+]
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/memcontrol.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN mm/memcontrol.c~memcg-fix-endless-loop-in-__mem_cgroup_iter_next 
mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-fix-endless-loop-in-__mem_cgroup_iter_next
+++ a/mm/memcontrol.c
@@ -1127,8 +1127,8 @@ skip_node:
         * skipping css reference should be safe.
         */
        if (next_css) {
-               if ((next_css->flags & CSS_ONLINE) &&
-                               (next_css == &root->css || 
css_tryget(next_css)))
+               if ((next_css == &root->css) ||
+                   ((next_css->flags & CSS_ONLINE) && css_tryget(next_css)))
                        return mem_cgroup_from_css(next_css);
 
                prev_css = next_css;
_

Patches currently in -mm which might be from [email protected] are

origin.patch
mm-vmstat-fix-up-zone-state-accounting.patch
fs-cachefiles-use-add_to_page_cache_lru.patch
lib-radix-tree-radix_tree_delete_item.patch
mm-shmem-save-one-radix-tree-lookup-when-truncating-swapped-pages.patch
mm-filemap-move-radix-tree-hole-searching-here.patch
mm-fs-prepare-for-non-page-entries-in-page-cache-radix-trees.patch
mm-fs-prepare-for-non-page-entries-in-page-cache-radix-trees-fix.patch
mm-fs-store-shadow-entries-in-page-cache.patch
mm-thrash-detection-based-file-cache-sizing.patch
lib-radix_tree-tree-node-interface.patch
mm-keep-page-cache-radix-tree-nodes-in-check.patch
mm-keep-page-cache-radix-tree-nodes-in-check-fix.patch
mm-keep-page-cache-radix-tree-nodes-in-check-fix-fix.patch
mm-compaction-avoid-isolating-pinned-pages.patch
mm-implement-map_pages-for-page-cache-fix.patch

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