Re: [RFC][PATCH 1/6] mm: Introduce __GFP_NO_OOM_KILL

[Andrew Morton]

On Tue, 12 May 2009 00:14:23 +0200
"Rafael J. Wysocki" <rjw@xxxxxxx> wrote:

> On Monday 11 May 2009, David Rientjes wrote:
> > On Sun, 10 May 2009, Rafael J. Wysocki wrote:
> > 
> > > Index: linux-2.6/mm/page_alloc.c
> > > ===================================================================
> > > --- linux-2.6.orig/mm/page_alloc.c
> > > +++ linux-2.6/mm/page_alloc.c
> > > @@ -1619,8 +1619,12 @@ nofail_alloc:
> > >  			goto got_pg;
> > >  		}
> > >  
> > > -		/* The OOM killer will not help higher order allocs so fail */
> > > -		if (order > PAGE_ALLOC_COSTLY_ORDER) {
> > > +		/*
> > > +		 * The OOM killer will not help higher order allocs so fail.
> > > +		 * Also fail if the caller doesn't want the OOM killer to run.
> > > +		 */
> > > +		if (order > PAGE_ALLOC_COSTLY_ORDER
> > > +				|| (gfp_mask & __GFP_NO_OOM_KILL)) {
> > >  			clear_zonelist_oom(zonelist, gfp_mask);
> > >  			goto nopage;
> > >  		}
> > > Index: linux-2.6/include/linux/gfp.h
> > > ===================================================================
> > > --- linux-2.6.orig/include/linux/gfp.h
> > > +++ linux-2.6/include/linux/gfp.h
> > > @@ -51,8 +51,9 @@ struct vm_area_struct;
> > >  #define __GFP_THISNODE	((__force gfp_t)0x40000u)/* No fallback, no policies */
> > >  #define __GFP_RECLAIMABLE ((__force gfp_t)0x80000u) /* Page is reclaimable */
> > >  #define __GFP_MOVABLE	((__force gfp_t)0x100000u)  /* Page is movable */
> > > +#define __GFP_NO_OOM_KILL ((__force gfp_t)0x200000u)  /* Don't invoke out_of_memory() */
> > >  
> > > -#define __GFP_BITS_SHIFT 21	/* Room for 21 __GFP_FOO bits */
> > > +#define __GFP_BITS_SHIFT 22	/* Number of __GFP_FOO bits */
> > >  #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
> > >  
> > >  /* This equals 0, but use constants in case they ever change */
> > > 
> > 
> > Nack, unnecessary in mmotm and my patch series from 
> > http://lkml.org/lkml/2009/5/10/118.
> 
> Andrew, what's your opinion, please?

I don't understand which part of David's patch series is supposed to
address your requirement.  If it's "don't kill tasks which are in D
state" then that's a problem because right now I think that patch is
wrong.  It's still being discussed.

> I can wait with these patches until the dust settles in the mm land.

Yes, it is pretty dusty at present.  I'd suggest that finding something
else to do for a few days would be a wise step ;)

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