lockdep reports about recursive locking in kmemleak

[Andrey Vagin]

Hello,

I found a following message in dmesg. Probably we should to do something 
similar as for debug_objects, it sets own class for parent->list_lock. 
Does anyone want to fix that?

=============================================
[ INFO: possible recursive locking detected ]
3.3.0+ #87 Not tainted
---------------------------------------------
udevd/847 is trying to acquire lock:
 (&(&parent->list_lock)->rlock){-.-...}, at: [<ffffffff811783f1>] 
cache_alloc_refill+0xa1/0x300

but task is already holding lock:
 (&(&parent->list_lock)->rlock){-.-...}, at: [<ffffffff81177628>] 
cache_flusharray+0x68/0x180

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&(&parent->list_lock)->rlock);
  lock(&(&parent->list_lock)->rlock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by udevd/847:
 #0:  (&(&parent->list_lock)->rlock){-.-...}, at: [<ffffffff81177628>] 
cache_flusharray+0x68/0x180

stack backtrace:
Pid: 847, comm: udevd Not tainted 3.3.0+ #87
Call Trace:
 [<ffffffff810b835a>] __lock_acquire+0x126a/0x1730
 [<ffffffff810b73f2>] ? __lock_acquire+0x302/0x1730
 [<ffffffff810b88d1>] lock_acquire+0xb1/0x1a0
 [<ffffffff811783f1>] ? cache_alloc_refill+0xa1/0x300
 [<ffffffff8118cdb9>] ? create_object+0x39/0x2e0
 [<ffffffff8153a141>] _raw_spin_lock+0x41/0x50
 [<ffffffff811783f1>] ? cache_alloc_refill+0xa1/0x300
 [<ffffffff811783f1>] cache_alloc_refill+0xa1/0x300
 [<ffffffff810b73f2>] ? __lock_acquire+0x302/0x1730
 [<ffffffff8118cdb9>] ? create_object+0x39/0x2e0
 [<ffffffff81179cbc>] kmem_cache_alloc+0x2cc/0x320
 [<ffffffff8118cdb9>] create_object+0x39/0x2e0
 [<ffffffff810b73f2>] ? __lock_acquire+0x302/0x1730
 [<ffffffff8151fade>] kmemleak_alloc+0x5e/0xc0
 [<ffffffff81179b2c>] kmem_cache_alloc+0x13c/0x320
 [<ffffffff81294d99>] __debug_object_init+0x3b9/0x3d0
 [<ffffffff812944fa>] ? debug_object_activate+0xca/0x190
 [<ffffffff81294dff>] debug_object_init+0x1f/0x30
 [<ffffffff810767d7>] rcuhead_fixup_activate+0x27/0x70
 [<ffffffff81293d35>] debug_object_fixup+0x15/0x20
 [<ffffffff8129450c>] debug_object_activate+0xdc/0x190
 [<ffffffff81177b50>] ? kmem_cache_shrink+0x70/0x70
 [<ffffffff810f0d12>] __call_rcu+0x42/0x1e0
 [<ffffffff810f0ee5>] call_rcu_sched+0x15/0x20
 [<ffffffff81177113>] slab_destroy+0x153/0x160
 [<ffffffff81177628>] ? cache_flusharray+0x68/0x180
 [<ffffffff81177179>] free_block+0x59/0x230
 [<ffffffff81177655>] cache_flusharray+0x95/0x180
 [<ffffffff81176dbf>] ? kmem_cache_free+0x11f/0x320
 [<ffffffff81176f6c>] kmem_cache_free+0x2cc/0x320
 [<ffffffff8115b5b1>] ? __put_anon_vma+0x61/0xb0
 [<ffffffff8115b5b1>] __put_anon_vma+0x61/0xb0
 [<ffffffff8115bb8b>] unlink_anon_vmas+0x13b/0x1a0
 [<ffffffff8114fac1>] free_pgtables+0x91/0x120
 [<ffffffff81156101>] exit_mmap+0xb1/0x120
 [<ffffffff8104e24b>] mmput+0x7b/0x120
 [<ffffffff81053d68>] exit_mm+0x108/0x130
 [<ffffffff8153aa70>] ? _raw_spin_unlock_irq+0x30/0x50
 [<ffffffff81056277>] do_exit+0x167/0x970
 [<ffffffff811b36c3>] ? mntput+0x23/0x40
 [<ffffffff81192f6d>] ? fput+0x1ad/0x280
 [<ffffffff8153ae59>] ? retint_swapgs+0x13/0x1b
 [<ffffffff81056adb>] do_group_exit+0x5b/0xd0
 [<ffffffff81056b67>] sys_exit_group+0x17/0x20
 [<ffffffff81543729>] system_call_fastpath+0x16/0x1b



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