mm/page_alloc: don't re-init pageset in zone_pcp_update()

When memory hotplug is triggered, we call pageset_init() on
per-cpu-pagesets which both contain pages and are in use, causing both the
leakage of those pages and (potentially) bad behaviour if a page is
allocated from a pageset while it is being cleared.

Avoid this by factoring out pageset_set_high_and_batch() (which contains
all needed logic too set a pageset's ->high and ->batch inrespective of
system state) from zone_pageset_init() and using the new
pageset_set_high_and_batch() instead of zone_pageset_init() in
zone_pcp_update().

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 5 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 03a3f943d98e..fab9506273be 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4104,11 +4104,9 @@ static void pageset_set_high(struct per_cpu_pageset *p,
         pageset_update(&p->pcp, high, batch);
 }
 
-static void __meminit zone_pageset_init(struct zone *zone, int cpu)
+static void __meminit pageset_set_high_and_batch(struct zone *zone,
+                struct per_cpu_pageset *pcp)
 {
-        struct per_cpu_pageset *pcp = per_cpu_ptr(zone->pageset, cpu);
-
-        pageset_init(pcp);
         if (percpu_pagelist_fraction)
                 pageset_set_high(pcp,
                         (zone->managed_pages /
@@ -4117,6 +4115,14 @@ static void __meminit zone_pageset_init(struct zone *zone, int cpu)
                 pageset_set_batch(pcp, zone_batchsize(zone));
 }
 
+static void __meminit zone_pageset_init(struct zone *zone, int cpu)
+{
+        struct per_cpu_pageset *pcp = per_cpu_ptr(zone->pageset, cpu);
+
+        pageset_init(pcp);
+        pageset_set_high_and_batch(zone, pcp);
+}
+
 static void __meminit setup_zone_pageset(struct zone *zone)
 {
         int cpu;
@@ -6100,7 +6106,8 @@ void __meminit zone_pcp_update(struct zone *zone)
         unsigned cpu;
         mutex_lock(&pcp_batch_high_lock);
         for_each_possible_cpu(cpu)
-                zone_pageset_init(zone, cpu);
+                pageset_set_high_and_batch(zone,
+                                per_cpu_ptr(zone->pageset, cpu));
         mutex_unlock(&pcp_batch_high_lock);
 }
 #endif