I have 2.6.26-rc2-mm1 with Rik's splitvm patches. While booting the kernel, I

ran into the following. I searched my email quickly to see that no one else has

reported this problem. Lockdep seems to be complaining about the same lock being

held at the same location (the message is a bit confusing to me).
=============================================

[ INFO: possible recursive locking detected ]

2.6.26-rc2-mm1 #2

---------------------------------------------

insmod/1072 is trying to acquire lock:

 (&cls->mutex){--..}, at: [<ffffffff803eb2cc>] device_add+0x46e/0x5d7
but task is already holding lock:

 (&cls->mutex){--..}, at: [<ffffffff803eb2cc>] device_add+0x46e/0x5d7
other info that might help us debug this:

3 locks held by insmod/1072:

 #0:  (&ioc->sas_discovery_mutex){--..}, at: [<ffffffffa003e7e9>]

mptsas_probe+0x3a1/0x442 [mptsas]

 #1:  (&shost->scan_mutex){--..}, at: [<ffffffff80466cbd>]

scsi_scan_target+0x71/0xb0

 #2:  (&cls->mutex){--..}, at: [<ffffffff803eb2cc>] device_add+0x46e/0x5d7
stack backtrace:

Pid: 1072, comm: insmod Not tainted 2.6.26-rc2-mm1 #2
Call Trace:

 [<ffffffff80254545>] __lock_acquire+0x911/0xc4c

 [<ffffffff80254835>] ? __lock_acquire+0xc01/0xc4c

 [<ffffffff803eb2cc>] ? device_add+0x46e/0x5d7

 [<ffffffff8025490e>] lock_acquire+0x8e/0xb2

 [<ffffffff803eb2cc>] ? device_add+0x46e/0x5d7

 [<ffffffff8059e067>] mutex_lock_nested+0xf2/0x27f

 [<ffffffff803eb2cc>] ? device_add+0x46e/0x5d7

 [<ffffffff8059f80b>] ? _spin_unlock+0x26/0x2a

 [<ffffffff803eb2cc>] device_add+0x46e/0x5d7

 [<ffffffff803eb44e>] device_register+0x19/0x1d

 [<ffffffff803eb531>] device_create+0xdf/0x110

 [<ffffffff80253794>] ? trace_hardirqs_on_caller+0xf9/0x124

 [<ffffffff802537cc>] ? trace_hardirqs_on+0xd/0xf

 [<ffffffff8059df73>] ? mutex_unlock+0x9/0xb

 [<ffffffff803eed13>] ? kobj_map+0x119/0x12e

 [<ffffffff802a4488>] ? e...
[ message continues ]

looks like device_add() recursing - most likely with a different device
--

This is another instance of a problem being caused by semaphore to mutex

conversion in struct class;
There's another thread on this here:
http://marc.info/?t=121074904600001
James
--

Thanks for pointer, it does indeed look like a variant of the same problem
--

	Warm Regards,

	Balbir Singh

	Linux Technology Center

	IBM, ISTL

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