slub: fix a memory leak in get_partial_node()
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. Cc: <stable@vger.kernel.org> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
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@ -1514,15 +1514,19 @@ static inline void *acquire_slab(struct kmem_cache *s,
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freelist = page->freelist;
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freelist = page->freelist;
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counters = page->counters;
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counters = page->counters;
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new.counters = counters;
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new.counters = counters;
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if (mode)
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if (mode) {
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new.inuse = page->objects;
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new.inuse = page->objects;
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new.freelist = NULL;
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} else {
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new.freelist = freelist;
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}
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VM_BUG_ON(new.frozen);
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VM_BUG_ON(new.frozen);
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new.frozen = 1;
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new.frozen = 1;
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} while (!__cmpxchg_double_slab(s, page,
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} while (!__cmpxchg_double_slab(s, page,
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freelist, counters,
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freelist, counters,
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NULL, new.counters,
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new.freelist, new.counters,
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"lock and freeze"));
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"lock and freeze"));
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remove_partial(n, page);
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remove_partial(n, page);
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@ -1564,7 +1568,6 @@ static void *get_partial_node(struct kmem_cache *s,
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object = t;
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object = t;
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available = page->objects - page->inuse;
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available = page->objects - page->inuse;
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} else {
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} else {
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page->freelist = t;
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available = put_cpu_partial(s, page, 0);
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available = put_cpu_partial(s, page, 0);
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stat(s, CPU_PARTIAL_NODE);
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stat(s, CPU_PARTIAL_NODE);
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}
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}
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