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From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-mm@kvack.org, thomas.jarosch@intra2net.com
Subject: Re: [patch 1/1] alloc_pages(): permit get_zeroed_page(GFP_ATOMIC) from interrupt context
Date: Mon, 27 Aug 2007 13:33:47 -0700	[thread overview]
Message-ID: <20070827133347.424f83a6.akpm@linux-foundation.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0708271308380.5457@schroedinger.engr.sgi.com>

On Mon, 27 Aug 2007 13:13:16 -0700 (PDT)
Christoph Lameter <clameter@sgi.com> wrote:

> On Thu, 23 Aug 2007, akpm@linux-foundation.org wrote:
> 
> > See http://bugzilla.kernel.org/show_bug.cgi?id=8928
> > 
> > I think it makes sense to permit a non-BUGging get_zeroed_page(GFP_ATOMIC)
> > from interrupt context.
> 
> AFAIK this works now. GFP_ATOMIC does not set __GFP_HIGHMEM and thus the 
> check
> 
> 	VM_BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
> 
> does not trigger

The crash happens in

	clear_highpage
	->kmap_atomic
	  ->kmap_atomic_prot
	    ->BUG_ON(!pte_none(*(kmap_pte-idx)));

ie: this CPU held a kmap slot when the interrupt happened.


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  reply	other threads:[~2007-08-27 20:33 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-23 21:07 akpm, Andrew Morton
2007-08-27 20:13 ` Christoph Lameter
2007-08-27 20:33   ` Andrew Morton [this message]
2007-08-27 21:00     ` Christoph Lameter
2007-08-27 21:04       ` Andrew Morton
2007-08-27 21:20         ` Christoph Lameter
2007-08-27 21:32           ` Christoph Lameter
2007-08-27 21:34           ` Andrew Morton
2007-08-27 21:43             ` Christoph Lameter
2007-08-27 22:11               ` Andrew Morton
2007-08-27 22:12                 ` Christoph Lameter
2007-08-27 22:45                   ` Andrew Morton
2007-08-27 23:01                     ` Christoph Lameter
2007-08-27 23:40                       ` Andrew Morton
2007-08-27 23:48                         ` Christoph Lameter

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