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authorSasha Levin <sasha.levin@oracle.com>2013-06-10 15:18:00 -0400
committerPekka Enberg <penberg@kernel.org>2013-06-13 10:01:58 +0300
commit907985f48bc60818e291c631249f9bc84c83a06f (patch)
parent317ddd256b9c24b0d78fa8018f80f1e495481a10 (diff)
slab: prevent warnings when allocating with __GFP_NOWARN
Sasha Levin noticed that the warning introduced by commit 6286ae9 ("slab: Return NULL for oversized allocations) is being triggered: WARNING: CPU: 15 PID: 21519 at mm/slab_common.c:376 kmalloc_slab+0x2f/0xb0() can: request_module (can-proto-4) failed. mpoa: proc_mpc_write: could not parse '' Modules linked in: CPU: 15 PID: 21519 Comm: trinity-child15 Tainted: G W 3.10.0-rc4-next-20130607-sasha-00011-gcd78395-dirty #2 0000000000000009 ffff880020a95e30 ffffffff83ff4041 0000000000000000 ffff880020a95e68 ffffffff8111fe12 fffffffffffffff0 00000000000082d0 0000000000080000 0000000000080000 0000000001400000 ffff880020a95e78 Call Trace: [<ffffffff83ff4041>] dump_stack+0x4e/0x82 [<ffffffff8111fe12>] warn_slowpath_common+0x82/0xb0 [<ffffffff8111fe55>] warn_slowpath_null+0x15/0x20 [<ffffffff81243dcf>] kmalloc_slab+0x2f/0xb0 [<ffffffff81278d54>] __kmalloc+0x24/0x4b0 [<ffffffff8196ffe3>] ? security_capable+0x13/0x20 [<ffffffff812a26b7>] ? pipe_fcntl+0x107/0x210 [<ffffffff812a26b7>] pipe_fcntl+0x107/0x210 [<ffffffff812b7ea0>] ? fget_raw_light+0x130/0x3f0 [<ffffffff812aa5fb>] SyS_fcntl+0x60b/0x6a0 [<ffffffff8403ca98>] tracesys+0xe1/0xe6 Andrew Morton writes: __GFP_NOWARN is frequently used by kernel code to probe for "how big an allocation can I get". That's a bit lame, but it's used on slow paths and is pretty simple. However, SLAB would still spew a warning when a big allocation happens if the __GFP_NOWARN flag is _not_ set to expose kernel bugs. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> [ penberg@kernel.org: improve changelog ] Signed-off-by: Pekka Enberg <penberg@kernel.org>
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index ff3218a0f5e..2d414508e9e 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -373,8 +373,10 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
int index;
+ if (size > KMALLOC_MAX_SIZE) {
+ WARN_ON_ONCE(!(flags & __GFP_NOWARN));
return NULL;
+ }
if (size <= 192) {
if (!size)