Re: [PATCH 1/4] mm: Add __GFP_NO_OOM_KILL flag

Wu Fengguang
2009-05-03T11:54:50Z

On Sun, May 03, 2009 at 02:22:06AM +0200, Rafael J. Wysocki wrote:
> From: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
>
> > > Remind me: why can't we just allocate N pages at suspend-time?
> >
> > We need half of memory free. The reason we can't "just allocate" is
> > probably OOM killer; but my memories are quite weak :-(.
>
> hm. You'd think that with our splendid range of __GFP_foo falgs, there
> would be some combo which would suit this requirement but I can't
> immediately spot one.
>
> We can always add another I guess. Something like...
>
> Signed-off-by: Rafael J. Wysocki <rjw-KKrjLPT3xs0@public.gmane.org>
> ---
> include/linux/gfp.h | 3 ++-
> mm/page_alloc.c | 3 ++-
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> Index: linux-2.6/mm/page_alloc.c
> ===================================================================
> --- linux-2.6.orig/mm/page_alloc.c
> +++ linux-2.6/mm/page_alloc.c
> @@ -1620,7 +1620,8 @@ nofail_alloc:
> }
>
> /* The OOM killer will not help higher order allocs so fail */
> - if (order > PAGE_ALLOC_COSTLY_ORDER) {
> + 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 */
^ missed a white space :)