From: Michal Hocko <mhocko@xxxxxxxx>
Jia He has noticed that b9f00e147f27 ("mm, page_alloc: reduce branches
in zone_statistics") has an unintentional side effect that remote node
allocation requests are accounted as NUMA_MISS rathat than NUMA_HIT and
NUMA_OTHER if such a request doesn't use __GFP_OTHER_NODE. There are
many of these potentially because the flag is used very rarely while
we have many users of __alloc_pages_node.
Fix this by simply ignoring __GFP_OTHER_NODE (it can be removed in a
follow up patch) and treat all allocations that were satisfied from the
preferred zone's node as NUMA_HITS because this is the same node we
requested the allocation from in most cases. If this is not the local
node then we just account it as NUMA_OTHER rather than NUMA_LOCAL.
One downsize would be that an allocation request for a node which is
outside of the mempolicy nodemask would be reported as a hit which is a
bit weird but that was the case before b9f00e147f27 already.
Reported-by: Jia He <hejianet@xxxxxxxxx>
Fixes: b9f00e147f27 ("mm, page_alloc: reduce branches in zone_statistics")
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
mm/page_alloc.c | 16 ++++------------
1 file changed, 4 insertions(+), 12 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f6d5b73e1d7c..506946a902c5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2583,25 +2583,17 @@ int __isolate_free_page(struct page *page, unsigned int order)
* Update NUMA hit/miss statistics
*
* Must be called with interrupts disabled.
- *
- * When __GFP_OTHER_NODE is set assume the node of the preferred
- * zone is the local node. This is useful for daemons who allocate
- * memory on behalf of other processes.
*/
static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
gfp_t flags)
{
#ifdef CONFIG_NUMA
- int local_nid = numa_node_id();
- enum zone_stat_item local_stat = NUMA_LOCAL;
-
- if (unlikely(flags & __GFP_OTHER_NODE)) {
- local_stat = NUMA_OTHER;
- local_nid = preferred_zone->node;
- }
+ if (z->node == preferred_zone->node) {
+ enum zone_stat_item local_stat = NUMA_LOCAL;
- if (z->node == local_nid) {
__inc_zone_state(z, NUMA_HIT);
+ if (z->node != numa_node_id())
+ local_stat = NUMA_OTHER;
__inc_zone_state(z, local_stat);
} else {
__inc_zone_state(z, NUMA_MISS);
--
2.10.2
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