mm: page_alloc: only check the alloc flags and gfp_mask for dirty once

Currently it's calculated once per zone in the zonelist.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index da526905b4a5..30f327a720fd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1917,6 +1917,8 @@ get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
         nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */
         int zlc_active = 0;             /* set if using zonelist_cache */
         int did_zlc_setup = 0;          /* just call zlc_setup() one time */
+        bool consider_zone_dirty = (alloc_flags & ALLOC_WMARK_LOW) &&
+                                (gfp_mask & __GFP_WRITE);
 
         classzone_idx = zone_idx(preferred_zone);
 zonelist_scan:
@@ -1976,8 +1978,7 @@ zonelist_scan:
                  * will require awareness of zones in the
                  * dirty-throttling and the flusher threads.
                  */
-                if ((alloc_flags & ALLOC_WMARK_LOW) &&
-                    (gfp_mask & __GFP_WRITE) && !zone_dirty_ok(zone))
+                if (consider_zone_dirty && !zone_dirty_ok(zone))
                         continue;
 
                 mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];