From: Christoph Lameter <cl@linux.com>
To: JoonSoo Kim <js1304@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/3] slub: release a lock if freeing object with a lock is failed in __slab_free()
Date: Fri, 6 Jul 2012 09:34:01 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1207060928580.26790@router.home> (raw)
In-Reply-To: <CAAmzW4NJyX9e_dMyJBA5zDiVYVmL1vbUkaRHNoSbbhDZWW7iMg@mail.gmail.com>
On Fri, 6 Jul 2012, JoonSoo Kim wrote:
> For example,
> When we try to free object A at cpu 1, another process try to free
> object B at cpu 2 at the same time.
> object A, B is in same slab, and this slab is in full list.
>
> CPU 1 CPU 2
> prior = page->freelist; prior = page->freelist
> .... ...
> new.inuse--; new.inuse--;
> taking lock try to take the lock, but failed, so
> spinning...
> free success spinning...
> add_partial
> release lock taking lock
> fail cmpxchg_double_slab
> retry
> currently, we don't need lock
>
> At CPU2, we don't need lock anymore, because this slab already in partial list.
For that scenario we could also simply do a trylock there and redo
the loop if we fail. But still what guarantees that another process will
not modify the page struct between fetching the data and a successful
trylock?
--
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:[~2012-07-06 14:34 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <yes>
2012-06-08 17:23 ` [PATCH 1/4] slub: change declare of get_slab() to inline at all times Joonsoo Kim
2012-06-08 17:23 ` [PATCH 2/4] slub: use __cmpxchg_double_slab() at interrupt disabled place Joonsoo Kim
2012-06-08 17:23 ` [PATCH 3/4] slub: refactoring unfreeze_partials() Joonsoo Kim
2012-06-20 7:19 ` Pekka Enberg
2012-06-08 17:23 ` [PATCH 4/4] slub: deactivate freelist of kmem_cache_cpu all at once in deactivate_slab() Joonsoo Kim
2012-06-08 19:04 ` Christoph Lameter
2012-06-10 10:27 ` JoonSoo Kim
2012-06-22 18:34 ` JoonSoo Kim
2012-06-08 19:02 ` [PATCH 1/4] slub: change declare of get_slab() to inline at all times Christoph Lameter
2012-06-09 15:57 ` JoonSoo Kim
2012-06-11 15:04 ` Christoph Lameter
2012-06-22 18:22 ` [PATCH 1/3] slub: prefetch next freelist pointer in __slab_alloc() Joonsoo Kim
2012-06-22 18:22 ` [PATCH 2/3] slub: reduce failure of this_cpu_cmpxchg in put_cpu_partial() after unfreezing Joonsoo Kim
2012-07-04 13:05 ` Pekka Enberg
2012-07-05 14:20 ` Christoph Lameter
2012-08-16 7:06 ` Pekka Enberg
2012-06-22 18:22 ` [PATCH 3/3] slub: release a lock if freeing object with a lock is failed in __slab_free() Joonsoo Kim
2012-07-04 13:10 ` Pekka Enberg
2012-07-04 14:48 ` JoonSoo Kim
2012-07-05 14:26 ` Christoph Lameter
2012-07-06 14:19 ` JoonSoo Kim
2012-07-06 14:34 ` Christoph Lameter [this message]
2012-07-06 14:59 ` JoonSoo Kim
2012-07-06 15:10 ` Christoph Lameter
2012-07-08 16:19 ` JoonSoo Kim
2012-06-22 18:45 ` [PATCH 1/3 v2] slub: prefetch next freelist pointer in __slab_alloc() Joonsoo Kim
2012-07-04 12:58 ` JoonSoo Kim
2012-07-04 13:00 ` Pekka Enberg
2012-07-04 14:30 ` JoonSoo Kim
2012-07-04 15:08 ` Pekka Enberg
2012-07-04 15:26 ` Eric Dumazet
2012-07-04 15:48 ` JoonSoo Kim
2012-07-04 16:15 ` Eric Dumazet
2012-07-04 16:24 ` JoonSoo Kim
2012-07-04 15:45 ` JoonSoo Kim
2012-07-04 15:59 ` Pekka Enberg
2012-07-04 16:04 ` JoonSoo Kim
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=alpine.DEB.2.00.1207060928580.26790@router.home \
--to=cl@linux.com \
--cc=js1304@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=penberg@kernel.org \
/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