| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <CALWz4iygkxRUJX2bEhHp6nyEwyVA8w8WxNcQqzmXuMeH8kMuYA@mail.gmail.com>
Date: Thu, 13 Dec 2012 17:14:13 -0800
From: Ying Han <yinghan@...gle.com>
To: Michal Hocko <mhocko@...e.cz>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Johannes Weiner <hannes@...xchg.org>,
Tejun Heo <htejun@...il.com>,
Glauber Costa <glommer@...allels.com>,
Li Zefan <lizefan@...wei.com>
Subject: Re: [patch v2 3/6] memcg: rework mem_cgroup_iter to use cgroup iterators
On Wed, Dec 12, 2012 at 11:24 AM, Michal Hocko <mhocko@...e.cz> wrote:
> On Wed 12-12-12 10:06:52, Michal Hocko wrote:
>> On Tue 11-12-12 14:36:10, Ying Han wrote:
> [...]
>> > One exception is mem_cgroup_iter_break(), where the loop terminates
>> > with *leaked* refcnt and that is what the iter_break() needs to clean
>> > up. We can not rely on the next caller of the loop since it might
>> > never happen.
>>
>> Yes, this is true and I already have a half baked patch for that. I
>> haven't posted it yet but it basically checks all node-zone-prio
>> last_visited and removes itself from them on the way out in pre_destroy
>> callback (I just need to cleanup "find a new last_visited" part and will
>> post it).
>
> And a half baked patch - just compile tested
> ---
> From 1c976c079c383175c679e00115aee0ab8e215bf2 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@...e.cz>
> Date: Tue, 11 Dec 2012 21:02:39 +0100
> Subject: [PATCH] NOT READY YET - just compile tested
>
> memcg: remove memcg from the reclaim iterators
>
> Now that per-node-zone-priority iterator caches memory cgroups rather
> than their css ids we have to be careful and remove them from the
> iterator when they are on the way out otherwise they might hang for
> unbounded amount of time (until the global reclaim triggers the zone
> under priority to find out the group is dead and let it to find the
> final rest).
>
> This is solved by hooking into mem_cgroup_pre_destroy and checking all
> per-node-zone-priority iterators. If the current memcg is found in
> iter->last_visited then it is replaced by its left sibling or its parent
> otherwise. This guarantees that no group gets more reclaiming than
> necessary and the next iteration will continue seemingly.
>
> Spotted-by: Ying Han <yinghan@...gle.com>
> Not-signed-off-by-yet: Michal Hocko <mhocko@...e.cz>
> ---
> mm/memcontrol.c | 38 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 7134148..286db74 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -6213,12 +6213,50 @@ free_out:
> return ERR_PTR(error);
> }
>
> +static void mem_cgroup_remove_cached(struct mem_cgroup *memcg)
> +{
> + int node, zone;
> +
> + for_each_node(node) {
> + struct mem_cgroup_per_node *pn = memcg->info.nodeinfo[node];
> + int prio;
> +
> + for (zone = 0; zone < MAX_NR_ZONES; zone++) {
> + struct mem_cgroup_per_zone *mz;
> +
> + mz = &pn->zoneinfo[zone];
> + for (prio = 0; prio < DEF_PRIORITY + 1; prio++) {
> + struct mem_cgroup_reclaim_iter *iter;
> +
> + iter = &mz->reclaim_iter[prio];
> + rcu_read_lock();
> + spin_lock(&iter->iter_lock);
> + if (iter->last_visited == memcg) {
> + struct cgroup *cgroup, *prev;
> +
> + cgroup = memcg->css.cgroup;
> + prev = list_entry_rcu(cgroup->sibling.prev, struct cgroup, sibling);
> + if (&prev->sibling == &prev->parent->children)
> + prev = prev->parent;
> + iter->last_visited = mem_cgroup_from_cont(prev);
> +
> + /* TODO can we do this? */
> + css_put(&memcg->css);
> + }
> + spin_unlock(&iter->iter_lock);
> + rcu_read_unlock();
> + }
> + }
> + }
> +}
> +
> static void mem_cgroup_pre_destroy(struct cgroup *cont)
> {
> struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
>
> mem_cgroup_reparent_charges(memcg);
> mem_cgroup_destroy_all_caches(memcg);
> + mem_cgroup_remove_cached(memcg);
> }
>
> static void mem_cgroup_destroy(struct cgroup *cont)
> --
> 1.7.10.4
>
> --
> Michal Hocko
> SUSE Labs
I haven't tried this patch set yet. Before I am doing that, I am
curious whether changing the target reclaim to be consistent with
global reclaim something worthy to consider based my last reply:
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 53dcde9..3f158c5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1911,20 +1911,6 @@ static void shrink_zone(struct zone *zone,
struct scan_control *sc)
shrink_lruvec(lruvec, sc);
- /*
- * Limit reclaim has historically picked one memcg and
- * scanned it with decreasing priority levels until
- * nr_to_reclaim had been reclaimed. This priority
- * cycle is thus over after a single memcg.
- *
- * Direct reclaim and kswapd, on the other hand, have
- * to scan all memory cgroups to fulfill the overall
- * scan target for the zone.
- */
- if (!global_reclaim(sc)) {
- mem_cgroup_iter_break(root, memcg);
- break;
- }
memcg = mem_cgroup_iter(root, memcg, &reclaim);
} while (memcg);
}
--Ying
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists