Commit 01e586598b224d1a427acd8a7afa0b21e879d3a7
Committed by
Linus Torvalds
1 parent
426589f571
Exists in
ti-lsk-linux-4.1.y
and in
10 other branches
cgroup: release css->id after css_free
Currently, we release css->id in css_release_work_fn, right before calling css_free callback, so that when css_free is called, the id may have already been reused for a new cgroup. I am going to use css->id to create unique names for per memcg kmem caches. Since kmem caches are destroyed only on css_free, I need css->id to be freed after css_free was called to avoid name clashes. This patch therefore moves css->id removal to css_free_work_fn. To prevent css_from_id from returning a pointer to a stale css, it makes css_release_work_fn replace the css ptr at css_idr:css->id with NULL. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Showing 1 changed file with 7 additions and 3 deletions Side-by-side Diff
kernel/cgroup.c
... | ... | @@ -4373,16 +4373,20 @@ |
4373 | 4373 | { |
4374 | 4374 | struct cgroup_subsys_state *css = |
4375 | 4375 | container_of(work, struct cgroup_subsys_state, destroy_work); |
4376 | + struct cgroup_subsys *ss = css->ss; | |
4376 | 4377 | struct cgroup *cgrp = css->cgroup; |
4377 | 4378 | |
4378 | 4379 | percpu_ref_exit(&css->refcnt); |
4379 | 4380 | |
4380 | - if (css->ss) { | |
4381 | + if (ss) { | |
4381 | 4382 | /* css free path */ |
4383 | + int id = css->id; | |
4384 | + | |
4382 | 4385 | if (css->parent) |
4383 | 4386 | css_put(css->parent); |
4384 | 4387 | |
4385 | - css->ss->css_free(css); | |
4388 | + ss->css_free(css); | |
4389 | + cgroup_idr_remove(&ss->css_idr, id); | |
4386 | 4390 | cgroup_put(cgrp); |
4387 | 4391 | } else { |
4388 | 4392 | /* cgroup free path */ |
... | ... | @@ -4434,7 +4438,7 @@ |
4434 | 4438 | |
4435 | 4439 | if (ss) { |
4436 | 4440 | /* css release path */ |
4437 | - cgroup_idr_remove(&ss->css_idr, css->id); | |
4441 | + cgroup_idr_replace(&ss->css_idr, NULL, css->id); | |
4438 | 4442 | if (ss->css_released) |
4439 | 4443 | ss->css_released(css); |
4440 | 4444 | } else { |