[PATCH] mm: gfp_atomic comments

Clarify in comments that GFP_ATOMIC means both "don't sleep" and "use
emergency pools", hence both ALLOC_HARDER and ALLOC_HIGH.

Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 3 insertions, 1 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 8b2eab90abb6..da7ce8730e97 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -57,6 +57,7 @@ struct vm_area_struct;
                         __GFP_NOFAIL|__GFP_NORETRY|__GFP_NO_GROW|__GFP_COMP| \
                         __GFP_NOMEMALLOC|__GFP_HARDWALL)
 
+/* GFP_ATOMIC means both !wait (__GFP_WAIT not set) and use emergency pool */
 #define GFP_ATOMIC      (__GFP_HIGH)
 #define GFP_NOIO        (__GFP_WAIT)
 #define GFP_NOFS        (__GFP_WAIT | __GFP_IO)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ce991b173aa9..d41a0662d4da 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -931,7 +931,8 @@ restart:
          *
          * The caller may dip into page reserves a bit more if the caller
          * cannot run direct reclaim, or if the caller has realtime scheduling
-         * policy.
+         * policy or is asking for __GFP_HIGH memory.  GFP_ATOMIC requests will
+         * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH).
          */
         alloc_flags = ALLOC_WMARK_MIN;
         if ((unlikely(rt_task(p)) && !in_interrupt()) || !wait)