Not sure why the code tries to unlock the rcu. The only case where slab grabs the lock is around mem_cgroup_get_kmem_cache() call, which won't result into calling cache_grow() (that tries to unlock the rcu).
===================================== [ BUG: bad unlock balance detected! ] 3.4.0-rc4+ #33 Not tainted ------------------------------------- swapper/0/0 is trying to release lock (rcu_read_lock) at: [<ffffffff8134f0b4>] cache_grow.constprop.63+0xe8/0x371 but there are no more locks to release!
other info that might help us debug this: no locks held by swapper/0/0.
stack backtrace: Pid: 0, comm: swapper/0 Not tainted 3.4.0-rc4+ #33 Call Trace: [<ffffffff8134f0b4>] ? cache_grow.constprop.63+0xe8/0x371 [<ffffffff8134cf09>] print_unlock_inbalance_bug.part.26+0xd1/0xd9 [<ffffffff8134f0b4>] ? cache_grow.constprop.63+0xe8/0x371 [<ffffffff8106865e>] print_unlock_inbalance_bug+0x4e/0x50 [<ffffffff8134f0b4>] ? cache_grow.constprop.63+0xe8/0x371 [<ffffffff8106cb26>] __lock_release+0xd6/0xe0 [<ffffffff8106cb8c>] lock_release+0x5c/0x80 [<ffffffff8134f0cc>] cache_grow.constprop.63+0x100/0x371 [<ffffffff8134f5c6>] cache_alloc_refill+0x289/0x2dc [<ffffffff810bf682>] ? kmem_cache_alloc+0x92/0x260 [<ffffffff81676a0f>] ? pidmap_init+0x79/0xb2 [<ffffffff810bf842>] kmem_cache_alloc+0x252/0x260 [<ffffffff810bf5f0>] ? kmem_freepages+0x180/0x180 [<ffffffff81676a0f>] pidmap_init+0x79/0xb2 [<ffffffff81667aa3>] start_kernel+0x297/0x2f8 [<ffffffff8166769e>] ? repair_env_string+0x5a/0x5a [<ffffffff816672fd>] x86_64_start_reservations+0x101/0x105 [<ffffffff816673f1>] x86_64_start_kernel+0xf0/0xf7
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- include/linux/slab_def.h | 2 -- 1 file changed, 2 deletions(-)
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h index c4f7e45..2d371ae 100644 --- a/include/linux/slab_def.h +++ b/include/linux/slab_def.h @@ -245,13 +245,11 @@ mem_cgroup_kmem_cache_prepare_sleep(struct kmem_cache *cachep) * enabled. */ kmem_cache_get_ref(cachep); - rcu_read_unlock(); }
static inline void mem_cgroup_kmem_cache_finish_sleep(struct kmem_cache *cachep) { - rcu_read_lock(); kmem_cache_drop_ref(cachep); }