mm, page_alloc: use masks and shifts when converting GFP flags to migrate types
This patch redefines which GFP bits are used for specifying mobility and
the order of the migrate types. Once redefined it's possible to convert
GFP flags to a migrate type with a simple mask and shift. The only
downside is that readers of OOM kill messages and allocation failures may
have been used to the existing values but scripts/gfp-translate will help.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index f92cbd2..440fca3 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -14,7 +14,7 @@
#define ___GFP_HIGHMEM 0x02u
#define ___GFP_DMA32 0x04u
#define ___GFP_MOVABLE 0x08u
-#define ___GFP_WAIT 0x10u
+#define ___GFP_RECLAIMABLE 0x10u
#define ___GFP_HIGH 0x20u
#define ___GFP_IO 0x40u
#define ___GFP_FS 0x80u
@@ -29,7 +29,7 @@
#define ___GFP_NOMEMALLOC 0x10000u
#define ___GFP_HARDWALL 0x20000u
#define ___GFP_THISNODE 0x40000u
-#define ___GFP_RECLAIMABLE 0x80000u
+#define ___GFP_WAIT 0x80000u
#define ___GFP_NOACCOUNT 0x100000u
#define ___GFP_NOTRACK 0x200000u
#define ___GFP_NO_KSWAPD 0x400000u
@@ -126,6 +126,7 @@
/* This mask makes up all the page movable related flags */
#define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
+#define GFP_MOVABLE_SHIFT 3
/* Control page allocator reclaim behavior */
#define GFP_RECLAIM_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS|\
@@ -152,14 +153,15 @@
/* Convert GFP flags to their corresponding migrate type */
static inline int gfpflags_to_migratetype(const gfp_t gfp_flags)
{
- WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
+ VM_WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
+ BUILD_BUG_ON((1UL << GFP_MOVABLE_SHIFT) != ___GFP_MOVABLE);
+ BUILD_BUG_ON((___GFP_MOVABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_MOVABLE);
if (unlikely(page_group_by_mobility_disabled))
return MIGRATE_UNMOVABLE;
/* Group based on mobility */
- return (((gfp_flags & __GFP_MOVABLE) != 0) << 1) |
- ((gfp_flags & __GFP_RECLAIMABLE) != 0);
+ return (gfp_flags & GFP_MOVABLE_MASK) >> GFP_MOVABLE_SHIFT;
}
#ifdef CONFIG_HIGHMEM