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Subject[PATCH 6/9] mm: __GFP_EMERGENCY
__GFP_EMERGENCY will allow the allocation to disregard the watermarks, 
much like PF_MEMALLOC.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/gfp.h | 7 ++++++-
mm/internal.h | 10 +++++++---
2 files changed, 13 insertions(+), 4 deletions(-)
Index: linux-2.6-git/include/linux/gfp.h
===================================================================
--- linux-2.6-git.orig/include/linux/gfp.h 2006-12-14 10:02:18.000000000 +0100
+++ linux-2.6-git/include/linux/gfp.h 2006-12-14 10:02:52.000000000 +0100
@@ -35,17 +35,21 @@ struct vm_area_struct;
#define __GFP_HIGH ((__force gfp_t)0x20u) /* Should access emergency pools? */
#define __GFP_IO ((__force gfp_t)0x40u) /* Can start physical IO? */
#define __GFP_FS ((__force gfp_t)0x80u) /* Can call down to low-level FS? */
+
#define __GFP_COLD ((__force gfp_t)0x100u) /* Cache-cold page required */
#define __GFP_NOWARN ((__force gfp_t)0x200u) /* Suppress page allocation failure warning */
#define __GFP_REPEAT ((__force gfp_t)0x400u) /* Retry the allocation. Might fail */
#define __GFP_NOFAIL ((__force gfp_t)0x800u) /* Retry for ever. Cannot fail */
+
#define __GFP_NORETRY ((__force gfp_t)0x1000u)/* Do not retry. Might fail */
#define __GFP_NO_GROW ((__force gfp_t)0x2000u)/* Slab internal usage */
#define __GFP_COMP ((__force gfp_t)0x4000u)/* Add compound page metadata */
#define __GFP_ZERO ((__force gfp_t)0x8000u)/* Return zeroed page on success */
+
#define __GFP_NOMEMALLOC ((__force gfp_t)0x10000u) /* Don't use emergency reserves */
#define __GFP_HARDWALL ((__force gfp_t)0x20000u) /* Enforce hardwall cpuset memory allocs */
#define __GFP_THISNODE ((__force gfp_t)0x40000u)/* No fallback, no policies */
+#define __GFP_EMERGENCY ((__force gfp_t)0x80000u) /* Use emergency reserves */

#define __GFP_BITS_SHIFT 20 /* Room for 20 __GFP_FOO bits */
#define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
@@ -54,7 +58,8 @@ struct vm_area_struct;
#define GFP_LEVEL_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS| \
__GFP_COLD|__GFP_NOWARN|__GFP_REPEAT| \
__GFP_NOFAIL|__GFP_NORETRY|__GFP_NO_GROW|__GFP_COMP| \
- __GFP_NOMEMALLOC|__GFP_HARDWALL|__GFP_THISNODE)
+ __GFP_NOMEMALLOC|__GFP_HARDWALL|__GFP_THISNODE| \
+ __GFP_EMERGENCY)

/* This equals 0, but use constants in case they ever change */
#define GFP_NOWAIT (GFP_ATOMIC & ~__GFP_HIGH)
Index: linux-2.6-git/mm/internal.h
===================================================================
--- linux-2.6-git.orig/mm/internal.h 2006-12-14 10:02:52.000000000 +0100
+++ linux-2.6-git/mm/internal.h 2006-12-14 10:02:52.000000000 +0100
@@ -75,7 +75,9 @@ static int inline gfp_to_alloc_flags(gfp
alloc_flags |= ALLOC_HARDER;

if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
- if (!in_irq() && (p->flags & PF_MEMALLOC))
+ if (gfp_mask & __GFP_EMERGENCY)
+ alloc_flags |= ALLOC_NO_WATERMARKS;
+ else if (!in_irq() && (p->flags & PF_MEMALLOC))
alloc_flags |= ALLOC_NO_WATERMARKS;
else if (!in_interrupt() &&
unlikely(test_thread_flag(TIF_MEMDIE)))
@@ -103,7 +105,7 @@ static inline int alloc_flags_to_rank(in
return rank;
}

-static inline int gfp_to_rank(gfp_t gfp_mask)
+static __always_inline int gfp_to_rank(gfp_t gfp_mask)
{
/*
* Although correct this full version takes a ~3% performance
@@ -118,7 +120,9 @@ static inline int gfp_to_rank(gfp_t gfp_
*/

if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
- if (!in_irq() && (current->flags & PF_MEMALLOC))
+ if (gfp_mask & __GFP_EMERGENCY)
+ return 0;
+ else if (!in_irq() && (current->flags & PF_MEMALLOC))
return 0;
else if (!in_interrupt() &&
unlikely(test_thread_flag(TIF_MEMDIE)))
--

-
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