Subject: + vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined.patch added to -mm tree
To: mhocko@xxxxxxx,anton.vorontsov@xxxxxxxxxx,hannes@xxxxxxxxxxx,kamezawa.hiroyu@xxxxxxxxxxxxxx,kosaki.motohiro@xxxxxxxxxxxxxx,lizefan@xxxxxxxxxx,tj@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 19 Jul 2013 16:00:56 -0700
The patch titled
Subject: vmpressure: make sure there are no events queued after memcg is offlined
has been added to the -mm tree. Its filename is
vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined.patch
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxx>
Subject: vmpressure: make sure there are no events queued after memcg is offlined
vmpressure is called synchronously from reclaim where the target_memcg is
guaranteed to be alive but the eventfd is signaled from the work queue
context. This means that memcg (along with vmpressure structure which is
embedded into it) might go away while the work item is pending which would
result in use-after-release bug.
We have two possible ways how to fix this. Either vmpressure pins memcg
before it schedules vmpr->work and unpin it in vmpressure_work_fn or
explicitely flush the work item from the css_offline context (as suggested
by Tejun).
This patch implements the later one and it introduces vmpressure_cleanup
which flushes the vmpressure work queue item item. It hooks into
mem_cgroup_css_offline after the memcg itself is cleaned up.
Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
Reported-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/vmpressure.h | 1 +
mm/memcontrol.c | 1 +
mm/vmpressure.c | 16 ++++++++++++++++
3 files changed, 18 insertions(+)
diff -puN include/linux/vmpressure.h~vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined include/linux/vmpressure.h
--- a/include/linux/vmpressure.h~vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined
+++ a/include/linux/vmpressure.h
@@ -30,6 +30,7 @@ extern void vmpressure(gfp_t gfp, struct
extern void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio);
extern void vmpressure_init(struct vmpressure *vmpr);
+extern void vmpressure_cleanup(struct vmpressure * vmpr);
extern struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg);
extern struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr);
extern struct vmpressure *css_to_vmpressure(struct cgroup_subsys_state *css);
diff -puN mm/memcontrol.c~vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined mm/memcontrol.c
--- a/mm/memcontrol.c~vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined
+++ a/mm/memcontrol.c
@@ -6335,6 +6335,7 @@ static void mem_cgroup_css_offline(struc
mem_cgroup_invalidate_reclaim_iterators(memcg);
mem_cgroup_reparent_charges(memcg);
mem_cgroup_destroy_all_caches(memcg);
+ vmpressure_cleanup(&memcg->vmpressure);
}
static void mem_cgroup_css_free(struct cgroup *cont)
diff -puN mm/vmpressure.c~vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined mm/vmpressure.c
--- a/mm/vmpressure.c~vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined
+++ a/mm/vmpressure.c
@@ -372,3 +372,19 @@ void vmpressure_init(struct vmpressure *
INIT_LIST_HEAD(&vmpr->events);
INIT_WORK(&vmpr->work, vmpressure_work_fn);
}
+
+/**
+ * vmpressure_cleanup() - shuts down vmpressure control structure
+ * @vmpr: Structure to be cleaned up
+ *
+ * This function should be called before the structure in which it is
+ * embedded is cleaned up.
+ */
+void vmpressure_cleanup(struct vmpressure *vmpr)
+{
+ /*
+ * Make sure there is no pending work before eventfd infrastructure
+ * goes away.
+ */
+ flush_work(&vmpr->work);
+}
_
Patches currently in -mm which might be from mhocko@xxxxxxx are
vmpressure-change-vmpressure-sr_lock-to-spinlock.patch
vmpressure-do-not-check-for-pending-work-to-prevent-from-new-work.patch
vmpressure-make-sure-there-are-no-events-queued-after-memcg-is-offlined.patch
include-linux-schedh-dont-use-task-pid-tgid-in-same_thread_group-has_group_leader_pid.patch
staging-lustre-ldlm-convert-to-shrinkers-to-count-scan-api.patch
staging-lustre-obdclass-convert-lu_object-shrinker-to-count-scan-api.patch
staging-lustre-ptlrpc-convert-to-new-shrinker-api.patch
staging-lustre-libcfs-cleanup-linux-memh.patch
staging-lustre-replace-num_physpages-with-totalram_pages.patch
inode-convert-inode-lru-list-to-generic-lru-list-code-inode-move-inode-to-a-different-list-inside-lock.patch
list_lru-per-node-list-infrastructure-fix-broken-lru_retry-behaviour.patch
list_lru-remove-special-case-function-list_lru_dispose_all.patch
xfs-convert-dquot-cache-lru-to-list_lru-fix-dquot-isolation-hang.patch
list_lru-dynamically-adjust-node-arrays-super-fix-for-destroy-lrus.patch
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