linux-kernel - Re: Regression in 3.8-rc1: "BUG: sleeping function called from invalid context"

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Message-ID: <1356199828.21834.8500.camel@edumazet-glaptop>
Date:	Sat, 22 Dec 2012 10:10:28 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Larry Finger <Larry.Finger@...inger.net>,
	LKML <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Pekka Enberg <penberg@...nel.org>, netdev@...r.kernel.org
Subject: Re: Regression in 3.8-rc1:  "BUG: sleeping function called from
 invalid context"

On Sat, 2012-12-22 at 19:02 +0100, Borislav Petkov wrote:
> Top-posting so that the rest can remain untouched.
> 
> Right, so AFAICT, something is holding rtnl_mutex (probably some
> rtnetlink traffic) and device_rename() is doing kstrdup with
> GFP_KERNEL which, among others, has __GFP_WAIT and *that* triggers the
> might_sleep_if() check in slab_pre_alloc_hook():
> 
> static inline int slab_pre_alloc_hook(struct kmem_cache *s, gfp_t flags)
> {
>         flags &= gfp_allowed_mask;
>         lockdep_trace_alloc(flags);
>         might_sleep_if(flags & __GFP_WAIT);		<--- HERE
> 
> Adding Christoph and Pekka although the slub.c might_sleep stuff is from
> 2010. Still, they might have a better idea.
> 
> Oh well, let's add netdev while we're at it. :-)

RTNL is a mutex, its perfectly valid to use GFP_KERNEL while holding a
mutex.

As replied before your mail, fix for the problem is already in David
tree.

http://git.kernel.org/?p=linux/kernel/git/davem/net.git;a=commitdiff;h=30e6c9fa93cf3dbc7cc6df1d748ad25e4264545a


Bug was added in commit c91f6df2db4972d3cc983e6988b9abf1ad02f5f9 :

http://git.kernel.org/?p=linux/kernel/git/davem/net.git;a=commit;h=c91f6df2db4972d3cc983e6988b9abf1ad02f5f9


Thanks


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