Messages in this thread Patch in this message | | | Date | Fri, 08 Jun 2012 05:19:16 +0100 | From | Ben Hutchings <> | Subject | [ 36/82] slub: fix a memory leak in get_partial_node() |
| |
3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Joonsoo Kim <js1304@gmail.com>
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: Ben Hutchings <ben@decadent.org.uk> --- mm/slub.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/mm/slub.c +++ b/mm/slub.c @@ -1506,15 +1506,19 @@ 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); @@ -1556,7 +1560,6 @@ object = t; available = page->objects - page->inuse; } else { - page->freelist = t; available = put_cpu_partial(s, page, 0); } if (kmem_cache_debug(s) || available > s->cpu_partial / 2)
| |