[PATCH] mempool: NOMEMALLOC and NORETRY

Mempools have 2 problems.

The first is that mempool_alloc can possibly get stuck in __alloc_pages
when they should opt to fail, and take an element from their reserved pool.

The second is that it will happily eat emergency PF_MEMALLOC reserves
instead of going to their reserved pools.

Fix the first by passing __GFP_NORETRY in the allocation calls in
mempool_alloc.  Fix the second by introducing a __GFP_MEMPOOL flag which
directs the page allocator not to allocate from the reserve pool.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 848a1baac079..af7407e8cfc5 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -38,14 +38,16 @@ struct vm_area_struct;
 #define __GFP_NO_GROW   0x2000u /* Slab internal usage */
 #define __GFP_COMP      0x4000u /* Add compound page metadata */
 #define __GFP_ZERO      0x8000u /* Return zeroed page on success */
+#define __GFP_NOMEMALLOC 0x10000u /* Don't use emergency reserves */
 
-#define __GFP_BITS_SHIFT 16     /* Room for 16 __GFP_FOO bits */
+#define __GFP_BITS_SHIFT 20     /* Room for 20 __GFP_FOO bits */
 #define __GFP_BITS_MASK ((1 << __GFP_BITS_SHIFT) - 1)
 
 /* if you forget to add the bitmask here kernel will crash, period */
 #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_NOFAIL|__GFP_NORETRY|__GFP_NO_GROW|__GFP_COMP| \
+                        __GFP_NOMEMALLOC)
 
 #define GFP_ATOMIC      (__GFP_HIGH)
 #define GFP_NOIO        (__GFP_WAIT)