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Subject: Re: [RFC/PATCH v2] mm: Introduce GFP_PANIC for non-failing
 allocations
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Rik van Riel <riel@redhat.com>
Cc: Christoph Lameter <cl@linux.com>, Cyrill Gorcunov <gorcunov@gmail.com>,
       Andrew Morton <akpm@linux-foundation.org>, mingo@elte.hu, mel@csn.ul.ie,
       linux-kernel@vger.kernel.org, rientjes@google.com, xemul@openvz.org
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References: <20090504122740.GH4173@lenovo> <20090504131311.GA23330@elte.hu>
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	 <1241792580.28600.41.camel@penberg-laptop>
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Date: Fri, 08 May 2009 17:39:49 +0300
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Hi Rik,

On Fri, 2009-05-08 at 10:37 -0400, Rik van Riel wrote:
> > @@ -1556,7 +1556,8 @@ nofail_alloc:
> >  				zonelist, high_zoneidx, ALLOC_NO_WATERMARKS);
> >  			if (page)
> >  				goto got_pg;
> > -			if (gfp_mask & __GFP_NOFAIL) {
> > +			/* GFP_PANIC sets both flags */
> > +			if ((gfp_mask & __GFP_NOFAIL) && !(gfp_mask & __GFP_NORETRY)) {
> >  				congestion_wait(WRITE, HZ/50);
> 
> Do you mean ((gfp_mask & GFP_PANIC) == GFP_PANIC))  ?

No, we only want to loop if __GFP_NOFAIL is set but __GFP_NORETRY is not
set.

> 
> > @@ -1670,6 +1671,9 @@ nopage:
> >  		dump_stack();
> >  		show_mem();
> >  	}
> > +	if (unlikely(gfp_mask & GFP_PANIC))
> > +		panic("Out of memory: %s order: %d, gfp_mask:0x%x\n",
> > +			p->comm, order, gfp_mask);
> 
> Ditto here.

Yes, indeed. Fixed up. Thanks!