On 08/24/2015 02:09 PM, Mel Gorman wrote:
An allocation request will either use the given nodemask or the cpuset
current tasks mems_allowed. A cpuset retry will recheck the callers nodemask
and while it's trivial overhead during an extremely rare operation, also
unnecessary. This patch fixes it.
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2c1c3bf54d15..32d1cec124bc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3171,7 +3171,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
gfp_t alloc_mask; /* The gfp_t that was actually used for allocation */
struct alloc_context ac = {
.high_zoneidx = gfp_zone(gfp_mask),
- .nodemask = nodemask,
+ .nodemask = nodemask ? : &cpuset_current_mems_allowed,
Hm this is a functional change for atomic allocations with NULL
nodemask. ac.nodemask is passed down to __alloc_pages_slowpath() which
might determine that ALLOC_CPUSET is not to be used (because it's
atomic). Yet it would use the restricted ac.nodemask in
get_page_from_freelist() and elsewhere.
.migratetype = gfpflags_to_migratetype(gfp_mask),
};
@@ -3206,8 +3206,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
/* The preferred zone is used for statistics later */
preferred_zoneref = first_zones_zonelist(ac.zonelist, ac.high_zoneidx,
- ac.nodemask ? : &cpuset_current_mems_allowed,
- &ac.preferred_zone);
+ ac.nodemask, &ac.preferred_zone);
if (!ac.preferred_zone)
goto out;
ac.classzone_idx = zonelist_zone_idx(preferred_zoneref);
--
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