The patch titled
memcg-cpu-hotplug-aware-percpu-count-updates-fix
has been added to the -mm tree. Its filename is
memcg-cpu-hotplug-aware-percpu-count-updates-fix.patch
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out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: memcg-cpu-hotplug-aware-percpu-count-updates-fix
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
memcg-use-for_each_mem_cgroup.patch's function mem_cgroup_start_loop() is
wrong because it always scan IDs larger than ROOT of sub-tree.
(This works well in small test..)
css_get_next() scans IDs larger than given number. Then...
Assume a tree like this.
Root(id=1)--A(id=2)
|
--B(id=3)--C(id=4)
|
--D(id=5)
In above case, searching all cgroup under "B" works well because
all IDs larger than B will be visited. (3->4->5)
Here, rmdir "A" and mkdir "E" under "B".
Root(id=1)--B(id=3)--C(id=4)
|
--D(id=5)
|
--E(id=2) /* reuse freed ID */
E's ID is smaller than B's. So, all scan should be started from 1.
The routine will visit (2->3->4->5).
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)
diff -puN mm/memcontrol.c~memcg-cpu-hotplug-aware-percpu-count-updates-fix mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-cpu-hotplug-aware-percpu-count-updates-fix
+++ a/mm/memcontrol.c
@@ -697,12 +697,28 @@ static struct mem_cgroup *try_get_mem_cg
/* The caller has to guarantee "mem" exists before calling this */
static struct mem_cgroup *mem_cgroup_start_loop(struct mem_cgroup *mem)
{
- if (mem && css_tryget(&mem->css))
- return mem;
- if (!mem)
- return root_mem_cgroup; /*css_put/get against root is ignored*/
+ struct cgroup_subsys_state *css;
+ int found;
- return NULL;
+ if (!mem) /* ROOT cgroup has the smallest ID */
+ return root_mem_cgroup; /*css_put/get against root is ignored*/
+ if (!mem->use_hierarchy) {
+ if (css_tryget(&mem->css))
+ return mem;
+ return NULL;
+ }
+ rcu_read_lock();
+ /*
+ * searching a memory cgroup which has the smallest ID under given
+ * ROOT cgroup. (ID >= 1)
+ */
+ css = css_get_next(&mem_cgroup_subsys, 1, &mem->css, &found);
+ if (css && css_tryget(css))
+ mem = container_of(css, struct mem_cgroup, css);
+ else
+ mem = NULL;
+ rcu_read_unlock();
+ return mem;
}
static struct mem_cgroup *mem_cgroup_get_next(struct mem_cgroup *iter,
_
Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are
origin.patch
vfs-introduce-fmode_neg_offset-for-allowing-negative-f_pos.patch
vfs-introduce-fmode_neg_offset-for-allowing-negative-f_pos-fix.patch
oom-add-per-mm-oom-disable-count.patch
oom-add-per-mm-oom-disable-count-protect-oom_disable_count-with-task_lock-in-fork.patch
oom-add-per-mm-oom-disable-count-use-old_mm-for-oom_disable_count-in-exec.patch
oom-avoid-killing-a-task-if-a-thread-sharing-its-mm-cannot-be-killed.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix-fix.patch
oom-rewrite-error-handling-for-oom_adj-and-oom_score_adj-tunables.patch
oom-fix-locking-for-oom_adj-and-oom_score_adj.patch
memory-hotplug-fix-notifiers-return-value-check.patch
memory-hotplug-unify-is_removable-and-offline-detection-code.patch
memory-hotplug-unify-is_removable-and-offline-detection-code-checkpatch-fixes.patch
tracing-vmscan-add-trace-events-for-lru-list-shrinking.patch
writeback-account-for-time-spent-congestion_waited.patch
vmscan-synchronous-lumpy-reclaim-should-not-call-congestion_wait.patch
vmscan-narrow-the-scenarios-lumpy-reclaim-uses-synchrounous-reclaim.patch
vmscan-remove-dead-code-in-shrink_inactive_list.patch
vmscan-isolated_lru_pages-stop-neighbour-search-if-neighbour-cannot-be-isolated.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis-or-if-significant-congestion-is-not-being-encountered-in-the-current-zone.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis-or-if-significant-congestion-is-not-being-encounted-in-the-current-zone-fix.patch
memcg-fix-race-in-file_mapped-accouting-flag-management.patch
memcg-avoid-lock-in-updating-file_mapped-was-fix-race-in-file_mapped-accouting-flag-management.patch
memcg-use-for_each_mem_cgroup.patch
memcg-cpu-hotplug-aware-percpu-count-updates.patch
memcg-cpu-hotplug-aware-percpu-count-updates-fix.patch
memcg-cpu-hotplug-aware-quick-acount_move-detection.patch
memcg-cpu-hotplug-aware-quick-acount_move-detection-checkpatch-fixes.patch
memcg-generic-filestat-update-interface.patch
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