Re: [patch v2 3/6] memcg: rework mem_cgroup_iter to use cgroup iterators
From: Michal Hocko <hidden>
Date: 2012-12-07 17:27:38
Also in:
lkml
On Fri 07-12-12 09:12:25, Ying Han wrote:
On Fri, Dec 7, 2012 at 12:58 AM, Michal Hocko [off-list ref] wrote:quoted
On Thu 06-12-12 19:43:52, Ying Han wrote: [...]quoted
Forgot to mention, I was testing 3.7-rc6 with the two cgroup changes :Could you give a try to -mm tree as well. There are some changes for memcgs removal in that tree which are not in Linus's tree.I will give a try, which patchset you have in mind so i can double check?
Have a look at ba5e0e6be1c76fd37508b2825372b28a90a5b729 in my tree.
I didn't find the place where the css pins the memcg, which either something i missed or not in place in my tree.
Yeah, it is carefully hidden ;). css pins cgroup (last css_put will call dput on the cgroup dentry - via css_dput_fn) and the last reference to memcg is dropped from ->destroy callback (mem_cgroup_destroy) called from cgroup_diput.
I twisted the patch a bit to make it closer to your v2 version, but instead keep the mem_cgroup_put() as well as using css_tryget(). Again, my test is happy with it:
This is really strange, there must be something weird with ref counting going on. Anyway, thanks for your testing! I will try to enahance my testing some more next week.
quoted hunk ↗ jump to hunk
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f2eeee6..acec05a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c@@ -1004,6 +1004,7 @@ struct mem_cgroup *mem_cgroup_iter(structmem_cgroup *root, if (prev && reclaim->generation != iter->generation) { if (last_visited) { css_put(&last_visited->css); + mem_cgroup_put(last_visited); iter->last_visited = NULL; } spin_unlock(&iter->iter_lock);@@ -1041,15 +1042,22 @@ struct mem_cgroup *mem_cgroup_iter(structmem_cgroup *root, if (reclaim) { struct mem_cgroup *curr = memcg; - if (last_visited) + if (last_visited) { css_put(&last_visited->css); + mem_cgroup_put(last_visited); + } if (css && !memcg) curr = container_of(css, struct mem_cgroup, css); /* make sure that the cached memcg is not removed */ - if (curr) - css_get(&curr->css); + if (curr) { + mem_cgroup_get(curr); + if (!css_tryget(&curr->css)) { + mem_cgroup_put(curr); + curr = NULL; + } + } iter->last_visited = curr; if (!css) --Yingquoted
-- Michal Hocko SUSE Labs-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
-- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>