linux-kernel - Re: [tip:x86/urgent] x86-32: Restore irq stacks NUMA-aware allocations

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Message-ID: <20101029205915.GC6130@lenovo>
Date:	Sat, 30 Oct 2010 00:59:15 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Peter Zijlstra <peterz@...radead.org>, mingo@...hat.com,
	hpa@...or.com, linux-kernel@...r.kernel.org, brgerst@...il.com,
	tglx@...utronix.de, mingo@...e.hu,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86-32: Restore irq stacks NUMA-aware
	allocations

On Fri, Oct 29, 2010 at 10:53:07PM +0200, Eric Dumazet wrote:
> Le samedi 30 octobre 2010 à 00:28 +0400, Cyrill Gorcunov a écrit :
> > On Fri, Oct 29, 2010 at 08:32:26PM +0200, Peter Zijlstra wrote:
> > > On Fri, 2010-10-29 at 06:43 +0000, tip-bot for Eric Dumazet wrote:
> > > > +       irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
> > > > +                                              THREAD_FLAGS,
> > > > +                                              THREAD_ORDER)); 
> > > 
> > > Shouldn't we be checking for a NULL return from alloc_pages_node()
> > > before calling page_address() on it?
> > > --
> > 
> 
> I didnt check for NULL because original code was not either.
> 
> If you cannot allocate memory for the IRQ stack, only choice is to crash
> anyway.
> 
> Adding BUG_ON() is not that helpful in this respect.
> 

 I believe it was a nit in first place, so the BUG_ON simply tells to code
readers that we knew the NULL can happen here but there is simply no way
to continue then.

 Cyrill
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