INFO: suspicious RCU usage. on 3.3.0-rc7-next-20120316

From: Justin P. Mattock
Date: Sun Mar 18 2012 - 11:36:43 EST


with the current linux-next I am seeing this in dmesg..:

[ 3.643089] isapnp: No Plug & Play device found
[ 3.643690] Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled
[ 3.673061]
[ 3.699307] ===============================
[ 3.725757] [ INFO: suspicious RCU usage. ]
[ 3.752134] 3.3.0-rc7-next-20120316 #1 Not tainted
[ 3.778508] -------------------------------
[ 3.778510] kernel/cgroup.c:1719 suspicious rcu_dereference_check() usage!
[ 3.778512]
[ 3.778512] other info that might help us debug this:
[ 3.778513]
[ 3.778515]
[ 3.778515] rcu_scheduler_active = 1, debug_locks = 1
[ 3.778517] no locks held by swapper/0/1.
[ 3.778517]
[ 3.778518] stack backtrace:
[ 3.778519] Pid: 1, comm: swapper/0 Not tainted 3.3.0-rc7-next-20120316 #1
[ 3.778521] Call Trace:
[ 3.778528] [<c158cc21>] ? printk+0x1d/0x1f
[ 3.778534] [<c10a822a>] lockdep_rcu_suspicious+0xca/0x100
[ 3.778536] [<c10bedea>] cgroup_path+0x17a/0x1c0
[ 3.778540] [<c12d4e92>] ? __raw_spin_lock_init+0x32/0x60
[ 3.778545] [<c12b9eba>] blkg_lookup_create+0x1aa/0x430
[ 3.778548] [<c1596ec5>] ? _raw_spin_lock_irq+0x55/0x60
[ 3.778550] [<c12bc32b>] blk_throtl_init+0x11b/0x210
[ 3.778552] [<c12bc24a>] ? blk_throtl_init+0x3a/0x210
[ 3.778554] [<c12ba600>] blkcg_init_queue+0x30/0x80
[ 3.778558] [<c129fc77>] blk_alloc_queue_node+0x1e7/0x220
[ 3.778560] [<c129fcc2>] blk_alloc_queue+0x12/0x20
[ 3.778563] [<c13a4139>] brd_alloc+0x69/0x180
[ 3.778566] [<c1398ab5>] ? device_pm_init+0x65/0x90
[ 3.778569] [<c186f0e7>] brd_init+0xb0/0x185
[ 3.778574] [<c138fe07>] ? device_register+0x17/0x20
[ 3.778577] [<c1003034>] do_one_initcall+0x34/0x170
[ 3.778578] [<c186f037>] ? regmap_initcall+0xc/0xc
[ 3.778582] [<c183e8d9>] kernel_init+0x103/0x198
[ 3.778584] [<c183e19a>] ? rdinit_setup+0x22/0x22
[ 3.778586] [<c183e7d6>] ? start_kernel+0x38b/0x38b
[ 3.778589] [<c159ef02>] kernel_thread_helper+0x6/0x10
[ 3.778592] [<c136d379>] ? tty_change_softcar+0x29/0xe0
[ 3.780902] brd: module loaded
[ 3.782352] loop: module loaded
[ 3.782641] ahci 0000:00:1f.2: version 3.


dmesg here:
http://fpaste.org/CpBD/

from what I remember I was doing a git pull and ran out of memory then ran git pull again and everything seemed alright, so I proceeded with building and running this kernel on reboot this showed up.

Justin P. Mattock
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