From: Michal Hocko <mhocko@suse.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Shakeel Butt <shakeelb@google.com>,
linux-mm@kvack.org, Vlastimil Babka <vbabka@suse.cz>,
kernel-team@fb.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 05/19] mm: memcontrol: decouple reference counting from page accounting
Date: Mon, 3 Aug 2020 17:08:58 +0200 [thread overview]
Message-ID: <20200803150858.GW5174@dhcp22.suse.cz> (raw)
In-Reply-To: <20200803150349.GA502356@cmpxchg.org>
On Mon 03-08-20 11:03:49, Johannes Weiner wrote:
> On Mon, Aug 03, 2020 at 11:00:33AM +0200, Michal Hocko wrote:
> > On Tue 23-06-20 10:40:23, Roman Gushchin wrote:
> > > @@ -5456,7 +5460,10 @@ static int mem_cgroup_move_account(struct page *page,
> > > */
> > > smp_mb();
> > >
> > > - page->mem_cgroup = to; /* caller should have done css_get */
> > > + css_get(&to->css);
> > > + css_put(&from->css);
> > > +
> > > + page->mem_cgroup = to;
> > >
> > > __unlock_page_memcg(from);
> >
> > What prevents from memcg to be released here?
>
> ->attach_task() and kill_css() are exclusive through the cgroup_mutex,
> so the base ref cannot disappear from under us during this operation.
OK, is this worth a comment? Reference counting before other operation
on the object always makes me worried and those details are hidden
elsewhere.
Btw. with the follow up fix from Hugh
Acked-by: Michal Hocko <mhocko@suse.com>
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-08-03 15:09 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 17:40 [PATCH v7 00/19] The new cgroup slab memory controller Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 01/19] mm: memcg: factor out memcg- and lruvec-level changes out of __mod_lruvec_state() Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 02/19] mm: memcg: prepare for byte-sized vmstat items Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 03/19] mm: memcg: convert vmstat slab counters to bytes Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 04/19] mm: slub: implement SLUB version of obj_to_index() Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 05/19] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
2020-08-03 9:00 ` Michal Hocko
2020-08-03 15:03 ` Johannes Weiner
2020-08-03 15:08 ` Michal Hocko [this message]
2020-06-23 17:40 ` [PATCH v7 06/19] mm: memcg/slab: obj_cgroup API Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 07/19] mm: memcg/slab: allocate obj_cgroups for non-root slab pages Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 08/19] mm: memcg/slab: save obj_cgroup for non-root slab objects Roman Gushchin
2020-07-16 16:55 ` Naresh Kamboju
2020-07-16 20:07 ` Roman Gushchin
2020-07-17 5:34 ` Naresh Kamboju
2020-06-23 17:40 ` [PATCH v7 10/19] mm: memcg/slab: deprecate memory.kmem.slabinfo Roman Gushchin
2020-06-24 1:43 ` Shakeel Butt
2020-06-24 1:53 ` Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 11/19] mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.h Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 12/19] mm: memcg/slab: use a single set of kmem_caches for all accounted allocations Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 13/19] mm: memcg/slab: simplify memcg cache creation Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 14/19] mm: memcg/slab: remove memcg_kmem_get_cache() Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 15/19] mm: memcg/slab: deprecate slab_root_caches Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 16/19] mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo() Roman Gushchin
2020-06-23 17:40 ` [PATCH v7 17/19] mm: memcg/slab: use a single set of kmem_caches for all allocations Roman Gushchin
2020-07-18 17:24 ` Guenter Roeck
2020-07-18 23:03 ` Roman Gushchin
-- strict thread matches above, loose matches on Subject: below --
2020-06-23 1:58 [PATCH v7 00/19] The new cgroup slab memory controller Roman Gushchin
2020-06-23 1:58 ` [PATCH v7 05/19] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
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=20200803150858.GW5174@dhcp22.suse.cz \
--to=mhocko@suse.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--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=shakeelb@google.com \
--cc=vbabka@suse.cz \
/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).