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Message-ID: <1321948113.27077.24.camel@edumazet-laptop>
Date: Tue, 22 Nov 2011 08:48:33 +0100
From: Eric Dumazet <eric.dumazet@...il.com>
To: Christoph Lameter <cl@...ux.com>
Cc: Christian Kujau <lists@...dbynature.de>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Markus Trippelsdorf <markus@...ppelsdorf.de>,
"Alex,Shi" <alex.shi@...el.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
Pekka Enberg <penberg@...nel.org>,
Matt Mackall <mpm@...enic.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Tejun Heo <tj@...nel.org>
Subject: Re: WARNING: at mm/slub.c:3357, kernel BUG at mm/slub.c:3413
Le lundi 21 novembre 2011 à 21:18 -0600, Christoph Lameter a écrit :
> Hmmm... That means that c->page points to page not frozen. Per cpu
> partial pages are frozen until they are reused or until the partial list
> is flushed.
>
> Does this ever happen on x86 or only on other platforms? In put_cpu_partial() the
> this_cpu_cmpxchg really needs really to be irq safe. this_cpu_cmpxchg is
> only preempt safe.
>
> Index: linux-2.6/mm/slub.c
> ===================================================================
> --- linux-2.6.orig/mm/slub.c 2011-11-21 21:15:41.575673204 -0600
> +++ linux-2.6/mm/slub.c 2011-11-21 21:16:33.442336849 -0600
> @@ -1969,7 +1969,7 @@
> page->pobjects = pobjects;
> page->next = oldpage;
>
> - } while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage);
> + } while (irqsafe_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage);
> stat(s, CPU_PARTIAL_FREE);
> return pobjects;
> }
>
For x86, I wonder if our !X86_FEATURE_CX16 support is correct on SMP
machines.
this_cpu_cmpxchg16b_emu() claims to be IRQ safe, but may be buggy...
Could we have somewhere a NMI handler calling kmalloc() ?
Please Markus send us :
cat /proc/cpuinfo
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