Re: [Slub allocator] There are chances that kmem_cache_cpu->freelist gets lost if the process happens to be rescheduled to a differenet cpu before the local_irq_save() completes in __slab_alloc()

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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Christoph Lameter <cl@linux.com>
Cc: zhihua che <zhihua.che@gmail.com>,
	linux-kernel@vger.kernel.org,
	Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [Slub allocator] There are chances that kmem_cache_cpu->freelist gets lost if the process happens to be rescheduled to a differenet cpu before the local_irq_save() completes in __slab_alloc()
Date: Mon, 12 Dec 2011 20:31:38 +0100	[thread overview]
Message-ID: <1323718298.2583.21.camel@edumazet-laptop> (raw)
In-Reply-To: <alpine.DEB.2.00.1112121252430.31975@router.home>

Le lundi 12 décembre 2011 à 12:53 -0600, Christoph Lameter a écrit :
> On Mon, 12 Dec 2011, Eric Dumazet wrote:
> 
> > Indeed, I reproduced the leak with hackbench and lot of threads.
> 
> Ran it here and did not see anything. But obviously this is an issue.
> Strange that no one noticed earlier. Usage of CONFIG_PREEMPT must not be
> that frequent.
> 

Yes, probably :(

All I did was using hackbench with 4000 threads on my 16 cpu machine,

while :; do hackbench 100 process 2000 ; done

I got about one leak (freelist chain, so several objects leaked) per
second.

next prev parent reply	other threads:[~2011-12-12 19:31 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-12 14:28 zhihua che
2011-12-12 15:09 ` Eric Dumazet
2011-12-12 15:50   ` Christoph Lameter
2011-12-12 17:39     ` Eric Dumazet
2011-12-12 18:53       ` Christoph Lameter
2011-12-12 19:31         ` Eric Dumazet [this message]
2011-12-13  3:57       ` Eric Dumazet
2011-12-13  4:47         ` zhihua che
2011-12-13 16:27         ` Christoph Lameter
2011-12-13 20:11           ` Pekka Enberg

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