linux-kernel - Re: [PATCH 4/4] slub: deactivate freelist of kmem_cache_cpu all at once in deactivate

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAAmzW4OuyCJVEHd823LvN3+uz=MN-4HGYyw8pbSUvhBN79wSjQ@mail.gmail.com>
Date:	Sun, 10 Jun 2012 19:27:27 +0900
From:	JoonSoo Kim <js1304@...il.com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Pekka Enberg <penberg@...nel.org>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 4/4] slub: deactivate freelist of kmem_cache_cpu all at
 once in deactivate_slab()

2012/6/9 Christoph Lameter <cl@...ux.com>:
> On Sat, 9 Jun 2012, Joonsoo Kim wrote:
>
>> Current implementation of deactivate_slab() which deactivate
>> freelist of kmem_cache_cpu one by one is inefficient.
>> This patch changes it to deactivate freelist all at once.
>> But, there is no overall performance benefit,
>> because deactivate_slab() is invoked infrequently.
>
> Hmm, deactivate freelist can race with slab_free. Need to look at this in
> detail.

Implemented logic is nearly same as previous one.
I just merge first step of previous deactivate_slab() with second one.
In case of failure of cmpxchg_double_slab(), reloading page->freelist,
page->counters and recomputing inuse
ensure that race with slab_free() cannot be possible.
In case that we need a lock, try to get a lock before invoking
cmpxchg_double_slab(),
so race with slab_free cannot be occured too.

Above is my humble opinion, please give me some comments.
--
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/