| 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: <50254A0A.3080805@jp.fujitsu.com>
Date: Sat, 11 Aug 2012 02:51:06 +0900
From: Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Glauber Costa <glommer@...allels.com>
CC: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
cgroups@...r.kernel.org, devel@...nvz.org,
Michal Hocko <mhocko@...e.cz>,
Johannes Weiner <hannes@...xchg.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Christoph Lameter <cl@...ux.com>,
David Rientjes <rientjes@...gle.com>,
Pekka Enberg <penberg@...nel.org>,
Pekka Enberg <penberg@...helsinki.fi>,
Suleiman Souhlal <suleiman@...gle.com>
Subject: Re: [PATCH v2 09/11] memcg: propagate kmem limiting information to
children
(2012/08/09 22:01), Glauber Costa wrote:
> The current memcg slab cache management fails to present satisfatory
> hierarchical behavior in the following scenario:
>
> -> /cgroups/memory/A/B/C
>
> * kmem limit set at A,
> * A and B have no tasks,
> * span a new task in in C.
>
> Because kmem_accounted is a boolean that was not set for C, no
> accounting would be done. This is, however, not what we expect.
>
> The basic idea, is that when a cgroup is limited, we walk the tree
> upwards (something Kame and I already thought about doing for other
> purposes), and make sure that we store the information about the parent
> being limited in kmem_accounted (that is turned into a bitmap: two
> booleans would not be space efficient). The code for that is taken from
> sched/core.c. My reasons for not putting it into a common place is to
> dodge the type issues that would arise from a common implementation
> between memcg and the scheduler - but I think that it should ultimately
> happen, so if you want me to do it now, let me know.
>
> We do the reverse operation when a formerly limited cgroup becomes
> unlimited.
>
> Signed-off-by: Glauber Costa <glommer@...allels.com>
> CC: Christoph Lameter <cl@...ux.com>
> CC: Pekka Enberg <penberg@...helsinki.fi>
> CC: Michal Hocko <mhocko@...e.cz>
> CC: Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> CC: Johannes Weiner <hannes@...xchg.org>
> CC: Suleiman Souhlal <suleiman@...gle.com>
> ---
> mm/memcontrol.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 79 insertions(+), 9 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 3216292..3d30b79 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -295,7 +295,8 @@ struct mem_cgroup {
> * Should the accounting and control be hierarchical, per subtree?
> */
> bool use_hierarchy;
> - bool kmem_accounted;
> +
> + unsigned long kmem_accounted; /* See KMEM_ACCOUNTED_*, below */
>
> bool oom_lock;
> atomic_t under_oom;
> @@ -348,6 +349,38 @@ struct mem_cgroup {
> #endif
> };
>
> +enum {
> + KMEM_ACCOUNTED_THIS, /* accounted by this cgroup itself */
> + KMEM_ACCOUNTED_PARENT, /* accounted by any of its parents. */
> +};
> +
> +#ifdef CONFIG_MEMCG_KMEM
> +static bool memcg_kmem_account(struct mem_cgroup *memcg)
> +{
> + return !test_and_set_bit(KMEM_ACCOUNTED_THIS, &memcg->kmem_accounted);
> +}
> +
> +static bool memcg_kmem_clear_account(struct mem_cgroup *memcg)
> +{
> + return test_and_clear_bit(KMEM_ACCOUNTED_THIS, &memcg->kmem_accounted);
> +}
> +
> +static bool memcg_kmem_is_accounted(struct mem_cgroup *memcg)
> +{
> + return test_bit(KMEM_ACCOUNTED_THIS, &memcg->kmem_accounted);
> +}
> +
> +static void memcg_kmem_account_parent(struct mem_cgroup *memcg)
> +{
> + set_bit(KMEM_ACCOUNTED_PARENT, &memcg->kmem_accounted);
> +}
> +
> +static void memcg_kmem_clear_account_parent(struct mem_cgroup *memcg)
> +{
> + clear_bit(KMEM_ACCOUNTED_PARENT, &memcg->kmem_accounted);
> +}
> +#endif /* CONFIG_MEMCG_KMEM */
> +
> /* Stuffs for move charges at task migration. */
> /*
> * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
> @@ -614,7 +647,7 @@ EXPORT_SYMBOL(__memcg_kmem_free_page);
>
> static void disarm_kmem_keys(struct mem_cgroup *memcg)
> {
> - if (memcg->kmem_accounted)
> + if (test_bit(KMEM_ACCOUNTED_THIS, &memcg->kmem_accounted))
> static_key_slow_dec(&memcg_kmem_enabled_key);
> }
> #else
> @@ -4171,17 +4204,54 @@ static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
> static void memcg_update_kmem_limit(struct mem_cgroup *memcg, u64 val)
> {
> #ifdef CONFIG_MEMCG_KMEM
> - /*
> - * Once enabled, can't be disabled. We could in theory disable it if we
> - * haven't yet created any caches, or if we can shrink them all to
> - * death. But it is not worth the trouble.
> - */
> + struct mem_cgroup *iter;
> +
> mutex_lock(&set_limit_mutex);
> - if (!memcg->kmem_accounted && val != RESOURCE_MAX) {
> + if ((val != RESOURCE_MAX) && memcg_kmem_account(memcg)) {
> +
> + /*
> + * Once enabled, can't be disabled. We could in theory disable
> + * it if we haven't yet created any caches, or if we can shrink
> + * them all to death. But it is not worth the trouble
> + */
> static_key_slow_inc(&memcg_kmem_enabled_key);
> - memcg->kmem_accounted = true;
> +
> + if (!memcg->use_hierarchy)
> + goto out;
> +
> + for_each_mem_cgroup_tree(iter, memcg) {
> + if (iter == memcg)
> + continue;
> + memcg_kmem_account_parent(iter);
> + }
Could you add an explanation comment ?
> + } else if ((val == RESOURCE_MAX) && memcg_kmem_clear_account(memcg)) {
> +
> + if (!memcg->use_hierarchy)
> + goto out;
> +
ditto.
> + for_each_mem_cgroup_tree(iter, memcg) {
> + struct mem_cgroup *parent;
> +
> + if (iter == memcg)
> + continue;
> + /*
> + * We should only have our parent bit cleared if none
> + * of our parents are accounted. The transversal order
> + * of our iter function forces us to always look at the
> + * parents.
> + */
> + parent = parent_mem_cgroup(iter);
> + for (; parent != memcg; parent = parent_mem_cgroup(iter))
> + if (memcg_kmem_is_accounted(parent))
> + goto noclear;
> + memcg_kmem_clear_account_parent(iter);
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
--
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