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authorJoonsoo Kim <js1304@gmail.com>2012-05-17 00:13:02 +0900
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-06-10 00:36:11 +0900
commit75df3ae2060eb00b909ac65fc4d2798c4e53969a (patch)
tree1a4fa75c42c7d182e4ab6595d3850de491cf0d0c
parent22aca500eb55daf5c84bffb001d3cce14da08b08 (diff)
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slub: fix a memory leak in get_partial_node()
commit 02d7633fa567be7bf55a993b79d2a31b95ce2227 upstream. In the case which is below, 1. acquire slab for cpu partial list 2. free object to it by remote cpu 3. page->freelist = t then memory leak is occurred. Change acquire_slab() not to zap freelist when it works for cpu partial list. I think it is a sufficient solution for fixing a memory leak. Below is output of 'slabinfo -r kmalloc-256' when './perf stat -r 30 hackbench 50 process 4000 > /dev/null' is done. ***Vanilla*** Sizes (bytes) Slabs Debug Memory ------------------------------------------------------------------------ Object : 256 Total : 468 Sanity Checks : Off Total: 3833856 SlabObj: 256 Full : 111 Redzoning : Off Used : 2004992 SlabSiz: 8192 Partial: 302 Poisoning : Off Loss : 1828864 Loss : 0 CpuSlab: 55 Tracking : Off Lalig: 0 Align : 8 Objects: 32 Tracing : Off Lpadd: 0 ***Patched*** Sizes (bytes) Slabs Debug Memory ------------------------------------------------------------------------ Object : 256 Total : 300 Sanity Checks : Off Total: 2457600 SlabObj: 256 Full : 204 Redzoning : Off Used : 2348800 SlabSiz: 8192 Partial: 33 Poisoning : Off Loss : 108800 Loss : 0 CpuSlab: 63 Tracking : Off Lalig: 0 Align : 8 Objects: 32 Tracing : Off Lpadd: 0 Total and loss number is the impact of this patch. Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--mm/slub.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 80848cd3901..71de9b5685f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1514,15 +1514,19 @@ static inline void *acquire_slab(struct kmem_cache *s,
freelist = page->freelist;
counters = page->counters;
new.counters = counters;
- if (mode)
+ if (mode) {
new.inuse = page->objects;
+ new.freelist = NULL;
+ } else {
+ new.freelist = freelist;
+ }
VM_BUG_ON(new.frozen);
new.frozen = 1;
} while (!__cmpxchg_double_slab(s, page,
freelist, counters,
- NULL, new.counters,
+ new.freelist, new.counters,
"lock and freeze"));
remove_partial(n, page);
@@ -1564,7 +1568,6 @@ static void *get_partial_node(struct kmem_cache *s,
object = t;
available = page->objects - page->inuse;
} else {
- page->freelist = t;
available = put_cpu_partial(s, page, 0);
stat(s, CPU_PARTIAL_NODE);
}