From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Nikolay Borisov <kernel@kyup.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/11] mm/slab: hold a slab_mutex when calling __kmem_cache_shrink()
Date: Fri, 1 Apr 2016 11:18:07 +0900 [thread overview]
Message-ID: <20160401021806.GA13179@js1304-P5Q-DELUXE> (raw)
In-Reply-To: <56FD019A.10906@kyup.com>
On Thu, Mar 31, 2016 at 01:53:14PM +0300, Nikolay Borisov wrote:
>
>
> On 03/28/2016 08:26 AM, js1304@gmail.com wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > Major kmem_cache metadata in slab subsystem is synchronized with
> > the slab_mutex. In SLAB, if some of them is changed, node's shared
> > array cache would be freed and re-populated. If __kmem_cache_shrink()
> > is called at the same time, it will call drain_array() with n->shared
> > without holding node lock so problem can happen.
> >
> > We can fix this small theoretical race condition by holding node lock
> > in drain_array(), but, holding a slab_mutex in kmem_cache_shrink()
> > looks more appropriate solution because stable state would make things
> > less error-prone and this is not performance critical path.
> >
> > In addtion, annotate on SLAB functions.
>
> Just a nit but would it not be better instead of doing comment-style
> annotation to use lockdep_assert_held/_once. In both cases for someone
> to understand what locks have to be held will go and read the source. In
> my mind it's easier to miss a comment line, rather than the
> lockdep_assert. Furthermore in case lockdep is enabled a locking
> violation would spew useful info to dmesg.
Good idea. I'm not sure if lockdep_assert is best fit but I will add
something to check it rather than just adding the comment.
Thanks.
--
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>
next prev parent reply other threads:[~2016-04-01 2:16 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-28 5:26 mm/slab: reduce lock contention in alloc path js1304
2016-03-28 5:26 ` [PATCH 01/11] mm/slab: hold a slab_mutex when calling __kmem_cache_shrink() js1304
2016-03-29 0:50 ` Christoph Lameter
2016-03-30 8:11 ` Joonsoo Kim
2016-03-31 10:53 ` Nikolay Borisov
2016-04-01 2:18 ` Joonsoo Kim [this message]
2016-03-28 5:26 ` [PATCH 02/11] mm/slab: remove BAD_ALIEN_MAGIC again js1304
2016-03-28 8:58 ` Geert Uytterhoeven
2016-03-30 8:11 ` Joonsoo Kim
2016-03-28 21:19 ` Andrew Morton
2016-03-29 0:53 ` Christoph Lameter
2016-03-28 5:26 ` [PATCH 03/11] mm/slab: drain the free slab as much as possible js1304
2016-03-29 0:54 ` Christoph Lameter
2016-03-28 5:26 ` [PATCH 04/11] mm/slab: factor out kmem_cache_node initialization code js1304
2016-03-29 0:56 ` Christoph Lameter
2016-03-30 8:12 ` Joonsoo Kim
2016-03-28 5:26 ` [PATCH 05/11] mm/slab: clean-up kmem_cache_node setup js1304
2016-03-29 0:58 ` Christoph Lameter
2016-03-30 8:15 ` Joonsoo Kim
2016-03-28 5:26 ` [PATCH 06/11] mm/slab: don't keep free slabs if free_objects exceeds free_limit js1304
2016-03-29 1:03 ` Christoph Lameter
2016-03-30 8:25 ` Joonsoo Kim
2016-03-28 5:26 ` [PATCH 07/11] mm/slab: racy access/modify the slab color js1304
2016-03-29 1:05 ` Christoph Lameter
2016-03-30 8:25 ` Joonsoo Kim
2016-03-28 5:26 ` [PATCH 08/11] mm/slab: make cache_grow() handle the page allocated on arbitrary node js1304
2016-03-28 5:26 ` [PATCH 09/11] mm/slab: separate cache_grow() to two parts js1304
2016-03-28 5:27 ` [PATCH 10/11] mm/slab: refill cpu cache through a new slab without holding a node lock js1304
2016-03-28 5:27 ` [PATCH 11/11] mm/slab: lockless decision to grow cache js1304
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=20160401021806.GA13179@js1304-P5Q-DELUXE \
--to=iamjoonsoo.kim@lge.com \
--cc=akpm@linux-foundation.org \
--cc=brouer@redhat.com \
--cc=cl@linux.com \
--cc=kernel@kyup.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=penberg@kernel.org \
--cc=rientjes@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