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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html