mm: add __GFP_OTHER_NODE flag

Add a new __GFP_OTHER_NODE flag to tell the low level numa statistics in
zone_statistics() that an allocation is on behalf of another thread.  This
way the local and remote counters can be still correct, even when
background daemons like khugepaged are changing memory mappings.

This only affects the accounting, but I think it's worth doing that right
to avoid confusing users.

I first tried to just pass down the right node, but this required a lot of
changes to pass down this parameter and at least one addition of a 10th
argument to a 9 argument function.  Using the flag is a lot less
intrusive.

Open: should be also used for migration?

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index dca31761b3110e92f5a0e28e47cef0c60d910cef..bfb8f934521e02b313cc1a497ec08850ac3493c1 100644 (file)
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -35,6 +35,7 @@ struct vm_area_struct;
 #define ___GFP_NOTRACK         0
 #endif
 #define ___GFP_NO_KSWAPD       0x400000u
+#define ___GFP_OTHER_NODE      0x800000u
 
 /*
  * GFP bitmasks..
@@ -83,6 +84,7 @@ struct vm_area_struct;
 #define __GFP_NOTRACK  ((__force gfp_t)___GFP_NOTRACK)  /* Don't track with kmemcheck */
 
 #define __GFP_NO_KSWAPD        ((__force gfp_t)___GFP_NO_KSWAPD)
+#define __GFP_OTHER_NODE ((__force gfp_t)___GFP_OTHER_NODE) /* On behalf of other node */
 
 /*
  * This may seem redundant, but it's a way of annotating false positives vs.

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 833e676d6d92c1e46336eca0b2206e3aa4273795..461c0119664ff88d2bf8797f2541ccae74ce0698 100644 (file)
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -220,12 +220,12 @@ static inline unsigned long node_page_state(int node,
                zone_page_state(&zones[ZONE_MOVABLE], item);
 }
 
-extern void zone_statistics(struct zone *, struct zone *);
+extern void zone_statistics(struct zone *, struct zone *, gfp_t gfp);
 
 #else
 
 #define node_page_state(node, item) global_page_state(item)
-#define zone_statistics(_zl,_z) do { } while (0)
+#define zone_statistics(_zl, _z, gfp) do { } while (0)
 
 #endif /* CONFIG_NUMA */
 

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6d0032bdb5d8ef3497379b4efc346c20ca573ff5..136a547262a0badb41bb7cce60ab4e7e91dcb301 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1337,7 +1337,7 @@ again:
        }
 
        __count_zone_vm_events(PGALLOC, zone, 1 << order);
-       zone_statistics(preferred_zone, zone);
+       zone_statistics(preferred_zone, zone, gfp_flags);
        local_irq_restore(flags);
 
        VM_BUG_ON(bad_range(zone, page));

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 0c3b5048773e6d486f43343a859ebf785161036e..772b39b87d955078b4f0d7a1b7114751e0ef9a74 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -500,8 +500,12 @@ void refresh_cpu_vm_stats(int cpu)
  * z       = the zone from which the allocation occurred.
  *
  * 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.
  */
-void zone_statistics(struct zone *preferred_zone, struct zone *z)
+void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)
 {
        if (z->zone_pgdat == preferred_zone->zone_pgdat) {
                __inc_zone_state(z, NUMA_HIT);
@@ -509,7 +513,8 @@ void zone_statistics(struct zone *preferred_zone, struct zone *z)
                __inc_zone_state(z, NUMA_MISS);
                __inc_zone_state(preferred_zone, NUMA_FOREIGN);
        }
-       if (z->node == numa_node_id())
+       if (z->node == ((flags & __GFP_OTHER_NODE) ?
+                       preferred_zone->node : numa_node_id()))
                __inc_zone_state(z, NUMA_LOCAL);
        else
                __inc_zone_state(z, NUMA_OTHER);