On 11/21/2012 12:18 AM, Andrew Morton wrote: > On Tue, 20 Nov 2012 13:18:19 +0400 > Glauber Costa <glommer@xxxxxxxxxxxxx> wrote: > >> On 11/12/2012 03:37 PM, Mel Gorman wrote: >>> diff --git a/include/linux/gfp.h b/include/linux/gfp.h >>> index 02c1c971..d0a7967 100644 >>> --- a/include/linux/gfp.h >>> +++ b/include/linux/gfp.h >>> @@ -31,6 +31,7 @@ struct vm_area_struct; >>> #define ___GFP_THISNODE 0x40000u >>> #define ___GFP_RECLAIMABLE 0x80000u >>> #define ___GFP_NOTRACK 0x200000u >>> +#define ___GFP_NO_KSWAPD 0x400000u >>> #define ___GFP_OTHER_NODE 0x800000u >>> #define ___GFP_WRITE 0x1000000u >> >> Keep in mind that this bit has been reused in -mm. >> If this patch needs to be reverted, we'll need to first change >> the definition of __GFP_KMEMCG (and __GFP_BITS_SHIFT as a result), or it >> would break things. > > I presently have > > /* Plain integer GFP bitmasks. Do not use this directly. */ > #define ___GFP_DMA 0x01u > #define ___GFP_HIGHMEM 0x02u > #define ___GFP_DMA32 0x04u > #define ___GFP_MOVABLE 0x08u > #define ___GFP_WAIT 0x10u > #define ___GFP_HIGH 0x20u > #define ___GFP_IO 0x40u > #define ___GFP_FS 0x80u > #define ___GFP_COLD 0x100u > #define ___GFP_NOWARN 0x200u > #define ___GFP_REPEAT 0x400u > #define ___GFP_NOFAIL 0x800u > #define ___GFP_NORETRY 0x1000u > #define ___GFP_MEMALLOC 0x2000u > #define ___GFP_COMP 0x4000u > #define ___GFP_ZERO 0x8000u > #define ___GFP_NOMEMALLOC 0x10000u > #define ___GFP_HARDWALL 0x20000u > #define ___GFP_THISNODE 0x40000u > #define ___GFP_RECLAIMABLE 0x80000u > #define ___GFP_KMEMCG 0x100000u > #define ___GFP_NOTRACK 0x200000u > #define ___GFP_NO_KSWAPD 0x400000u > #define ___GFP_OTHER_NODE 0x800000u > #define ___GFP_WRITE 0x1000000u > > and > Humm, I didn't realize there were also another free space at 0x100000u. This seems fine. > #define __GFP_BITS_SHIFT 25 /* Room for N __GFP_FOO bits */ > #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) > > Which I think is OK? Yes, if we haven't increased the size of the flag-space, no need to change it. > > I'd forgotten about __GFP_BITS_SHIFT. Should we do this? > > --- a/include/linux/gfp.h~a > +++ a/include/linux/gfp.h > @@ -35,6 +35,7 @@ struct vm_area_struct; > #define ___GFP_NO_KSWAPD 0x400000u > #define ___GFP_OTHER_NODE 0x800000u > #define ___GFP_WRITE 0x1000000u > +/* If the above are modified, __GFP_BITS_SHIFT may need updating */ > This is a very helpful comment. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>