This is a note to let you know that I've just added the patch titled
mm: fix remote numa hits statistics
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-fix-remote-numa-hits-statistics.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2df26639e708a88dcc22171949da638a9998f3bc Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@xxxxxxxx>
Date: Tue, 10 Jan 2017 16:57:39 -0800
Subject: mm: fix remote numa hits statistics
From: Michal Hocko <mhocko@xxxxxxxx>
commit 2df26639e708a88dcc22171949da638a9998f3bc upstream.
Jia He has noticed that commit 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.
Fixes: b9f00e147f27 ("mm, page_alloc: reduce branches in zone_statistics")
Link: http://lkml.kernel.org/r/20170102153057.9451-2-mhocko@xxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reported-by: Jia He <hejianet@xxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx> # with cbmc[1] superpowers
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Taku Izumi <izumi.taku@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2556,30 +2556,23 @@ int __isolate_free_page(struct page *pag
* 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)) {
+ if (z->node != numa_node_id())
local_stat = NUMA_OTHER;
- local_nid = preferred_zone->node;
- }
- if (z->node == local_nid) {
+ if (z->node == preferred_zone->node)
__inc_zone_state(z, NUMA_HIT);
- __inc_zone_state(z, local_stat);
- } else {
+ else {
__inc_zone_state(z, NUMA_MISS);
__inc_zone_state(preferred_zone, NUMA_FOREIGN);
}
+ __inc_zone_state(z, local_stat);
#endif
}
Patches currently in stable-queue which might be from mhocko@xxxxxxxx are
queue-4.9/mm-memcg-fix-the-active-list-aging-for-lowmem-requests-when-memcg-is-enabled.patch
queue-4.9/mm-fix-remote-numa-hits-statistics.patch
queue-4.9/mm-pmd-dirty-emulation-in-page-fault-handler.patch
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