From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Roman Gushchin <guro@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, Johannes Weiner <hannes@cmpxchg.org>,
Shakeel Butt <shakeelb@google.com>,
Waiman Long <longman@redhat.com>
Subject: Re: [PATCH v7 10/10] mm: reparent memcg kmem_caches on cgroup removal
Date: Sun, 16 Jun 2019 19:29:41 +0300 [thread overview]
Message-ID: <20190616162941.aqa4ae5j63nmjlp6@esperanza> (raw)
In-Reply-To: <20190611231813.3148843-11-guro@fb.com>
On Tue, Jun 11, 2019 at 04:18:13PM -0700, Roman Gushchin wrote:
> Let's reparent non-root kmem_caches on memcg offlining. This allows us
> to release the memory cgroup without waiting for the last outstanding
> kernel object (e.g. dentry used by another application).
>
> Since the parent cgroup is already charged, everything we need to do
> is to splice the list of kmem_caches to the parent's kmem_caches list,
> swap the memcg pointer, drop the css refcounter for each kmem_cache
> and adjust the parent's css refcounter.
>
> Please, note that kmem_cache->memcg_params.memcg isn't a stable
> pointer anymore. It's safe to read it under rcu_read_lock(),
> cgroup_mutex held, or any other way that protects the memory cgroup
> from being released.
>
> We can race with the slab allocation and deallocation paths. It's not
> a big problem: parent's charge and slab global stats are always
> correct, and we don't care anymore about the child usage and global
> stats. The child cgroup is already offline, so we don't use or show it
> anywhere.
>
> Local slab stats (NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE)
> aren't used anywhere except count_shadow_nodes(). But even there it
> won't break anything: after reparenting "nodes" will be 0 on child
> level (because we're already reparenting shrinker lists), and on
> parent level page stats always were 0, and this patch won't change
> anything.
>
> Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
next prev parent reply other threads:[~2019-06-16 16:29 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-11 23:18 [PATCH v7 00/10] mm: reparent slab memory on cgroup removal Roman Gushchin
2019-06-11 23:18 ` [PATCH v7 01/10] mm: postpone kmem_cache memcg pointer initialization to memcg_link_cache() Roman Gushchin
2019-06-13 2:04 ` Andrew Morton
2019-06-13 16:25 ` Roman Gushchin
2019-06-11 23:18 ` [PATCH v7 02/10] mm: rename slab delayed deactivation functions and fields Roman Gushchin
2019-06-25 18:17 ` Shakeel Butt
2019-06-11 23:18 ` [PATCH v7 03/10] mm: generalize postponed non-root kmem_cache deactivation Roman Gushchin
2019-06-25 18:17 ` Shakeel Butt
2019-06-11 23:18 ` [PATCH v7 04/10] mm: introduce __memcg_kmem_uncharge_memcg() Roman Gushchin
2019-06-11 23:18 ` [PATCH v7 05/10] mm: unify SLAB and SLUB page accounting Roman Gushchin
2019-06-11 23:18 ` [PATCH v7 06/10] mm: don't check the dying flag on kmem_cache creation Roman Gushchin
2019-06-16 16:26 ` Vladimir Davydov
2019-06-25 18:31 ` Shakeel Butt
2019-06-11 23:18 ` [PATCH v7 07/10] mm: synchronize access to kmem_cache dying flag using a spinlock Roman Gushchin
2019-06-16 16:27 ` Vladimir Davydov
2019-06-25 18:33 ` Shakeel Butt
2019-06-11 23:18 ` [PATCH v7 08/10] mm: rework non-root kmem_cache lifecycle management Roman Gushchin
2019-06-25 23:57 ` Shakeel Butt
2019-11-21 11:17 ` WARNING bisected (was Re: [PATCH v7 08/10] mm: rework non-root kmem_cache lifecycle management) Christian Borntraeger
2019-11-21 13:08 ` Christian Borntraeger
2019-11-21 16:58 ` Roman Gushchin
2019-11-21 16:59 ` Christian Borntraeger
2019-11-21 18:45 ` Roman Gushchin
2019-11-21 20:43 ` Rik van Riel
2019-11-21 20:55 ` Roman Gushchin
2019-11-21 22:09 ` Roman Gushchin
2019-11-22 13:00 ` Christian Borntraeger
2019-11-22 16:28 ` Christian Borntraeger
2019-11-24 0:39 ` Roman Gushchin
2019-11-25 8:00 ` Christian Borntraeger
2019-11-25 18:07 ` Roman Gushchin
2019-06-11 23:18 ` [PATCH v7 09/10] mm: stop setting page->mem_cgroup pointer for slab pages Roman Gushchin
2019-06-26 0:15 ` Shakeel Butt
2019-06-11 23:18 ` [PATCH v7 10/10] mm: reparent memcg kmem_caches on cgroup removal Roman Gushchin
2019-06-16 16:29 ` Vladimir Davydov [this message]
2019-06-26 0:15 ` Shakeel Butt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190616162941.aqa4ae5j63nmjlp6@esperanza \
--to=vdavydov.dev@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=longman@redhat.com \
--cc=shakeelb@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).