linux-kernel - Re: [patch] x86: fix broken flush_tlb_others

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Date:	Wed, 14 Jan 2009 08:32:45 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Suresh Siddha <suresh.b.siddha@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	hpa@...or.com, tglx@...utronix.de, travis@....com,
	rusty@...tcorp.com.au, linux-kernel@...r.kernel.org
Subject: Re: [patch] x86: fix broken flush_tlb_others_ipi()


* Suresh Siddha <suresh.b.siddha@...el.com> wrote:

> This commit broke flush_tlb_others_ipi() causing boot hangs on a
> 16 logical cpu system.
> 
> >	commit 4595f9620cda8a1e973588e743cf5f8436dd20c6
> >	Author: Rusty Russell <rusty@...tcorp.com.au>
> >	Date:   Sat Jan 10 21:58:09 2009 -0800
> >
> >	    x86: change flush_tlb_others to take a const struct cpumask
> 
> This change resulted in sending the invalidate tlb vector to the
> sender itself causing the hang. flush_tlb_others_ipi() should exclude
> the sender itself from the destination list.
> 
> Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
> ---
> 
> diff --git a/arch/x86/kernel/tlb_64.c b/arch/x86/kernel/tlb_64.c
> index 2d971a3..53289e1 100644
> --- a/arch/x86/kernel/tlb_64.c
> +++ b/arch/x86/kernel/tlb_64.c
> @@ -188,7 +188,7 @@ static void flush_tlb_others_ipi(const struct cpumask *cpumask,
>  	 * We have to send the IPI only to
>  	 * CPUs affected.
>  	 */
> -	send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR_START + sender);
> +	send_IPI_mask(f->flush_cpumask, INVALIDATE_TLB_VECTOR_START + sender);
>  
>  	while (!cpumask_empty(to_cpumask(f->flush_cpumask)))
>  		cpu_relax();

Good catch! This might explain one of the hangs i was seeing on a 
test-system.

	Ingo
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