linux-kernel - Re: percpu related boot crash on x86

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Message-ID: <1295521967.2825.15.camel@edumazet-laptop>
Date:	Thu, 20 Jan 2011 12:12:47 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Pekka Enberg <penberg@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	Tejun Heo <tj@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: percpu related boot crash on x86

Le jeudi 20 janvier 2011 à 11:47 +0100, Peter Zijlstra a écrit :
> On Thu, 2011-01-20 at 10:31 +0200, Pekka Enberg wrote:
> >    if (!irqs_disabled())
> > 
> > guard around the debugging code to make vfree() always work with IRQs 
> > disabled. 
> 
> That won't be sufficient, __purge_vmap_area_lazy() needs to call
> flush_tlb_kernel_range() occasionally.
> 
> There really is a good reason vmalloc()/vfree() don't work with
> interrupts disabled.
> 

Hmm, I would try to increase PERCPU_DYNAMIC_RESERVE, or pcpu_mem_alloc()
could try to use kzalloc() even for allocations bigger than one PAGE,
and fallback to vzalloc().

We have more alloc_percpu() uses, we also should try to use first chunk
if possible.



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