From: Steven Rostedt <rostedt@goodmis.org>
To: Christoph Lameter <cl@linux.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Pekka Enberg <penberg@kernel.org>, Matt Mackall <mpm@selenic.com>,
Thomas Gleixner <tglx@linutronix.de>,
RT <linux-rt-users@vger.kernel.org>,
Clark Williams <clark@redhat.com>, John Kacur <jkacur@gmail.com>,
"Luis Claudio R. Goncalves" <lgoncalv@redhat.com>
Subject: Re: [RFC][PATCH v2] slub: Keep page and object in sync in slab_alloc_node()
Date: Fri, 18 Jan 2013 10:55:01 -0500 [thread overview]
Message-ID: <1358524501.7383.17.camel@gandalf.local.home> (raw)
In-Reply-To: <1358521484.7383.8.camel@gandalf.local.home>
On Fri, 2013-01-18 at 10:04 -0500, Steven Rostedt wrote:
Just to be more complete:
> CPU0 CPU1
> ---- ----
c = __this_cpu_ptr(s->cpu_slab);
<migrates to CPU0>
> <cpu fetches c->page>
<another task>
> updates c->tid
> updates c->page
> updates c->freelist
> <cpu fetches c->tid>
> <cpu fetches c->freelist>
>
> node_match() succeeds even though
> current c->page wont
>
<migrates back to CPU 1>
> this_cpu_cmpxchg_double() only tests
> the object (freelist) and tid, both which
> will match, but the page that was tested
> isn't the right one.
>
Yes, it's very unlikely, but we are in the business of dealing with the
very unlikely. That's because in our business, the very unlikely is very
likely. Damn, I need to buy a lotto ticket!
-- Steve
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next prev parent reply other threads:[~2013-01-18 15:55 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-17 18:10 [RFC][PATCH] slub: Check for page NULL before doing the node_match check Steven Rostedt
2013-01-17 18:37 ` Steven Rostedt
2013-01-17 21:28 ` Christoph Lameter
2013-01-17 21:36 ` Eric Dumazet
2013-01-17 21:44 ` Steven Rostedt
2013-01-17 21:43 ` Steven Rostedt
2013-01-17 21:51 ` Christoph Lameter
2013-01-17 22:07 ` Steven Rostedt
2013-01-17 22:46 ` Steven Rostedt
2013-01-17 23:10 ` Steven Rostedt
2013-01-17 23:20 ` [RFC][PATCH] slub: Keep page and object in sync in slab_alloc_node() Steven Rostedt
2013-01-18 0:23 ` Steven Rostedt
2013-01-18 0:28 ` [RFC][PATCH v2] " Steven Rostedt
2013-01-18 4:42 ` Joonsoo Kim
2013-01-18 14:52 ` Christoph Lameter
2013-01-18 15:29 ` Steven Rostedt
2013-01-18 14:44 ` Christoph Lameter
2013-01-18 15:04 ` Steven Rostedt
2013-01-18 15:55 ` Steven Rostedt [this message]
2013-01-18 18:29 ` Christoph Lameter
2013-01-18 18:52 ` Steven Rostedt
2013-01-21 1:48 ` Christoph Lameter
2013-01-21 8:11 ` Joonsoo Kim
2013-01-21 12:19 ` Steven Rostedt
2013-01-18 18:23 ` Christoph Lameter
2013-01-18 15:09 ` [RFC][PATCH v3] " Steven Rostedt
2013-01-18 18:40 ` Christoph Lameter
2013-01-18 19:09 ` Eric Dumazet
2013-01-18 19:20 ` Steven Rostedt
2013-01-21 1:40 ` Christoph Lameter
2013-01-18 14:43 ` [RFC][PATCH] slub: Check for page NULL before doing the node_match check Christoph Lameter
[not found] ` <alpine.DEB.2.02.1301171547370.2774@gentwo.org>
2013-01-17 21:56 ` Christoph Lameter
2013-01-17 22:10 ` Steven Rostedt
2013-01-17 21:22 ` Christoph Lameter
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