Re: [BUG] Netfilter ipt_owner deadlock

[Patrick McHardy <kaber@trash.net>]

Unfortunately I also can't think of a solution except
for marking it broken on SMP ;(

Regards
Patrick

Harald Welte wrote:
> 
> ------------------------------------------------------------------------
> 
> Subject:
> [BUG] Netfilter ipt_owner deadlock
> From:
> Christophe Saout <christophe@saout.de>
> Date:
> Fri, 14 May 2004 17:19:05 +0200
> To:
> linux-net@vger.kernel.org
> 
> To:
> linux-net@vger.kernel.org
> 
> 
> Hi,
> 
> there's a nasty problem with the ipt_owner netfilter code:
> 
> It does a spin_lock(&files->file_lock), sometimes from softirq context.
> This can lead to deadlocks on SMP systems. The lock must not be taken
> from softirq context because the rest of the kernel doesn't use
> spin_lock_bh.
> 
> On a UP machine (that had an SMP compiled kernel) the machine repeatedly
> locked up after approx. five minutes. SysRQ shows backtraces like fput
> -> timer interrupt -> softirq -> ipv4 -> netfilter -> ipt_owner -> hang.
> 
> I don't see a clean solution for this (except for changing all the
> spin_locks to spin_lock_bhs which I think is way too aggressive).
> 
> Any ideas?
> 
> 
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