[PATCH v3 1/5] mm/slab: Fix drain freelist excessively

[Wanpeng Li <liwanp@linux.vnet.ibm.com>]

Changelog:
 v1 -> v2:
  * Fix the callers that pass # of objects. Make sure they pass # of slabs.
 v2 -> v3:
  * introduce helper function slabs_tofree 

The drain_freelist is called to drain slabs_free lists for cache reap,
cache shrink, memory hotplug callback etc. The tofree parameter should
be the number of slab to free instead of the number of slab objects to
free.

This patch fix the callers that pass # of objects. Make sure they pass #
of slabs.

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
---
 mm/slab.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index e6122b2..3002771 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1180,6 +1180,12 @@ static int init_cache_node_node(int node)
 	return 0;
 }
 
+static inline int slabs_tofree(struct kmem_cache *cachep,
+						struct kmem_cache_node *n)
+{
+	return (n->free_objects + cachep->num - 1) / cachep->num;
+}
+
 static void cpuup_canceled(long cpu)
 {
 	struct kmem_cache *cachep;
@@ -1241,7 +1247,7 @@ free_array_cache:
 		n = cachep->node[node];
 		if (!n)
 			continue;
-		drain_freelist(cachep, n, n->free_objects);
+		drain_freelist(cachep, n, slabs_tofree(cachep, n));
 	}
 }
 
@@ -1408,7 +1414,7 @@ static int __meminit drain_cache_node_node(int node)
 		if (!n)
 			continue;
 
-		drain_freelist(cachep, n, n->free_objects);
+		drain_freelist(cachep, n, slabs_tofree(cachep, n));
 
 		if (!list_empty(&n->slabs_full) ||
 		    !list_empty(&n->slabs_partial)) {
@@ -2532,7 +2538,7 @@ static int __cache_shrink(struct kmem_cache *cachep)
 		if (!n)
 			continue;
 
-		drain_freelist(cachep, n, n->free_objects);
+		drain_freelist(cachep, n, slabs_tofree(cachep, n));
 
 		ret += !list_empty(&n->slabs_full) ||
 			!list_empty(&n->slabs_partial);
-- 
1.8.1.2

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