mm: page_alloc: calculate classzone_idx once from the zonelist ref

PATCH In review Dan Carpenter 3 participants 3 messages May 20, 2014 – May 21, 2014

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Memory management Page allocator

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Dan Carpenter

author

2014-05-20 11:18 UTC #0 lore raw

Hello Mel Gorman,

The patch a486e00b8283: "mm: page_alloc: calculate classzone_idx once from the zonelist ref" from May 17, 2014, leads to the following static checker warning:

	mm/page_alloc.c:2543 __alloc_pages_slowpath()
	warn: we tested 'nodemask' before and it was 'false'

mm/page_alloc.c

  2537           * Find the true preferred zone if the allocation is unconstrained by
  2538           * cpusets.
  2539           */
  2540          if (!(alloc_flags & ALLOC_CPUSET) && !nodemask) {
                                                     ^^^^^^^^^

Patch introduces this test.

2541 struct zoneref *preferred_zoneref;
2542 preferred_zoneref = first_zones_zonelist(zonelist, high_zoneidx,
2543 nodemask ? : &cpuset_current_mems_allowed,

                                        ^^^^^^^^

Patch introduces this test as well.

  2544                                  &preferred_zone);
  2545                  classzone_idx = zonelist_zone_idx(preferred_zoneref);
  2546          }

regards,
dan carpenter

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Mel Gorman

2014-05-20 12:43 UTC #1 lore raw

PATCH 1/1 mm: page_alloc: Calculate classzone_idx once from the zonelist ref

Dan Carpenter reported the following bug

The patch a486e00b8283: "mm: page_alloc: calculate classzone_idx once from the zonelist ref" from May 17, 2014, leads to the following static checker warning:

mm/page_alloc.c:2543 __alloc_pages_slowpath()
warn: we tested 'nodemask' before and it was 'false'

mm/page_alloc.c

  2537           * Find the true preferred zone if the allocation is unconstrained by
  2538           * cpusets.
  2539           */
  2540          if (!(alloc_flags & ALLOC_CPUSET) && !nodemask) {
                                                     ^^^^^^^^^

Patch introduces this test.

2541 struct zoneref *preferred_zoneref;
2542 preferred_zoneref = first_zones_zonelist(zonelist, high_zoneidx,
2543 nodemask ? : &cpuset_current_mems_allowed,

                                        ^^^^^^^^

Patch introduces this test as well.

  2544                                  &preferred_zone);
  2545                  classzone_idx = zonelist_zone_idx(preferred_zoneref);
  2546          }

This patch should resolve it and is a fix to the mmotm patch mm-page_alloc-calculate-classzone_idx-once-from-the-zonelist-ref

Signed-off-by Mel Gorman <[email protected]>

---
 mm/page_alloc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

mm/page_alloc.c +1 -2

index 0959b09..ebb947d 100644
@@ -2590,8 +2590,7 @@ restart:
 	if (!(alloc_flags & ALLOC_CPUSET) && !nodemask) {
 		struct zoneref *preferred_zoneref;
 		preferred_zoneref = first_zones_zonelist(zonelist, high_zoneidx,
-				nodemask ? : &cpuset_current_mems_allowed,
-				&preferred_zone);
+				NULL, &preferred_zone);
 		classzone_idx = zonelist_zone_idx(preferred_zoneref);
 	}

David Rientjes

Acked-by on v1 1/1

2014-05-21 00:06 UTC #2 lore raw

Re: [PATCH] mm: page_alloc: Calculate classzone_idx once from the zonelist ref

Quoted 40 lines · Mel Gorman

Dan Carpenter reported the following bug
The patch a486e00b8283: "mm: page_alloc: calculate classzone_idx once from the zonelist ref" from May 17, 2014, leads to the following static checker warning:
mm/page_alloc.c:2543 __alloc_pages_slowpath()
warn: we tested 'nodemask' before and it was 'false'
mm/page_alloc.c
  2537           * Find the true preferred zone if the allocation is unconstrained by
  2538           * cpusets.
  2539           */
  2540          if (!(alloc_flags & ALLOC_CPUSET) && !nodemask) {
                                                     ^^^^^^^^^
Patch introduces this test.
2541 struct zoneref *preferred_zoneref;
2542 preferred_zoneref = first_zones_zonelist(zonelist, high_zoneidx,
2543 nodemask ? : &cpuset_current_mems_allowed,
                                        ^^^^^^^^
Patch introduces this test as well.
  2544                                  &preferred_zone);
  2545                  classzone_idx = zonelist_zone_idx(preferred_zoneref);
  2546          }
This patch should resolve it and is a fix to the mmotm patch mm-page_alloc-calculate-classzone_idx-once-from-the-zonelist-ref
Signed-off-by Mel Gorman <[email protected]>
---
 mm/page_alloc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
mm/page_alloc.c +0 -0
index 0959b09..ebb947d 100644

mm/page_alloc.c restart: · line 2596

Quoted 9 lines

mm/page_alloc.c +1 -2

@@ -2590,8 +2590,7 @@ restart:
 	if (!(alloc_flags & ALLOC_CPUSET) && !nodemask) {
 		struct zoneref *preferred_zoneref;
 		preferred_zoneref = first_zones_zonelist(zonelist, high_zoneidx,
-				nodemask ? : &cpuset_current_mems_allowed,
-				&preferred_zone);
+				NULL, &preferred_zone);
 		classzone_idx = zonelist_zone_idx(preferred_zoneref);
 	}

The switch from "nodemask : &cpuset_current_mems_allowed" to NULL isn't described in the changelog but makes sense as well because of !(alloc_flags & ALLOC_CPUSET).

Acked-by David Rientjes <[email protected]>