Date: Mon, 29 Mar 2004 16:21:23 -0800
From: Andrew Morton <akpm@osdl.org>
To: "Martin J. Bligh" <mbligh@aracnet.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: BUG_ON(!cpus_equal(cpumask, tmp));
Message-Id: <20040329162123.4c57734d.akpm@osdl.org>
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References: <006701c415a4$01df0770$d100000a@sbs2003.local>
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"Martin J. Bligh" <mbligh@aracnet.com> wrote:
>
> The bug is on "BUG_ON(!cpus_equal(cpumask, tmp));" in flush_tlb_others
> This was from 2.6.1-rc1-mjb1, and seems to be a race on shutdown
> (prints after "Power Down"), but I've no reason to believe it's specific
> to the patchset I have - it's not an area I'm touching, I think.
> 
> I presume we've got a race between taking CPUs offline and the 
> tlbflush code ... tlb_flush_mm reads the value from mm->cpu_vm_mask,
> and then presumably some other cpu changes cpu_online_map before it
> gets to calling flush_tlb_others ... does that sound about right?

Looks like it, yes.  I don't think there's a sane way of fixing that - we'd
need the flush_tlb_others() caller to hold some lock which keeps the cpu
add/remove code away.

I'd propose removing the assertion?
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