linux-kernel - Re: [BUG] lockup with the latest kernel

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Date:	Thu, 27 Aug 2009 21:05:32 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Tejun Heo <tj@...nel.org>
cc:	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [BUG] lockup with the latest kernel



On Fri, 28 Aug 2009, Tejun Heo wrote:
> > 
> >     x86: make x86_32 use tlb_64.c
> >     
> >     Impact: less contention when issuing invalidate IPI, cleanup
> >     
> >     Make x86_32 use the same tlb code as 64bit.  The 64bit code uses
> >     multiple IPI vectors for tlb shootdown to reduce contention.  This
> >     patch makes x86_32 allocate the same 8 IPIs as x86_64 and share the
> >     code paths.
> >     
> >     Note that the usage of asmlinkage is inconsistent for x86_32 and 64
> >     and calls for further cleanup.  This has been noted with a FIXME
> >     comment in tlb_64.c.
> >     
> >     Signed-off-by: Tejun Heo <tj@...nel.org>
> > 
> > I can easily hit this bug at this commit, but I ran for a week on the 
> > commit before it. Thus I'm assuming this is the bug (but I'm not 100% 
> > sure).
> 
> Drat, why does it have to be mine?  ;-)
> 
> Joke aside, thank you very much for bisecting it.
> 
> ...
> >> [13288.222084] EIP: 0060:[<c0110821>] EFLAGS: 00000002 CPU: 0
> >> [13288.222084] EIP is at default_send_IPI_mask_logical+0x53/0x92

Is this one perhaps fixed by b04e6373d694 ("x86: don't call 
'->send_IPI_mask()' with an empty mask")

It sounds a _lot_ like that bug. Older dual-cpu x86 box, and APIC getting 
confused by the occasional empty CPU mask, and then subsequent IPI's will 
hang.

		Linus
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