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Running 3.0-0.rc5.git0.1.fc16.x86_64 on F15. I got this: Description of problem: [ 3465.914487] [ 3465.914490] =================================================== [ 3465.914497] [ INFO: suspicious rcu_dereference_check() usage. ] [ 3465.914503] --------------------------------------------------- [ 3465.914510] block/cfq-iosched.c:2776 invoked rcu_dereference_check() without protection! [ 3465.914516] [ 3465.914517] other info that might help us debug this: [ 3465.914520] [ 3465.914525] [ 3465.914527] rcu_scheduler_active = 1, debug_locks = 0 [ 3465.914534] 3 locks held by scsi_scan_6/2097: [ 3465.914539] #0: (&shost->scan_mutex){+.+.+.}, at: [<ffffffff8133d968>] scsi_scan_host_selected+0xbf/0x191 [ 3465.914560] #1: (&eq->sysfs_lock){+.+...}, at: [<ffffffff8123902a>] elevator_exit+0x1d/0x4e [ 3465.914577] #2: (&(&q->__queue_lock)->rlock){-.-...}, at: [<ffffffff8125032f>] cfq_exit_queue+0x47/0x179 [ 3465.914592] [ 3465.914594] stack backtrace: [ 3465.914601] Pid: 2097, comm: scsi_scan_6 Not tainted 3.0-0.rc5.git0.1.fc16.x86_64 #1 [ 3465.914606] Call Trace: [ 3465.914616] [<ffffffff81086e4d>] lockdep_rcu_dereference+0xa8/0xb0 [ 3465.914626] [<ffffffff81250227>] __cfq_exit_single_io_context+0x78/0xd7 [ 3465.914635] [<ffffffff81250353>] cfq_exit_queue+0x6b/0x179 [ 3465.914643] [<ffffffff8123903e>] elevator_exit+0x31/0x4e [ 3465.914652] [<ffffffff8123d501>] blk_cleanup_queue+0x4f/0x68 [ 3465.914662] [<ffffffff8133b931>] scsi_free_queue+0xe/0x10 [ 3465.914671] [<ffffffff8133efb2>] __scsi_remove_device+0xac/0xb9 [ 3465.914681] [<ffffffff8133cee8>] scsi_probe_and_add_lun+0xa6e/0xaab [ 3465.914692] [<ffffffff8133d5ff>] __scsi_scan_target+0x580/0x5d2 [ 3465.914702] [<ffffffff81088007>] ? mark_lock+0x2d/0x220 [ 3465.914712] [<ffffffff81089654>] ? mark_held_locks+0x4b/0x6d [ 3465.914723] [<ffffffff814f35d0>] ? _raw_spin_unlock_irqrestore+0x45/0x52 [ 3465.914731] [<ffffffff81089781>] ? trace_hardirqs_on_caller+0x10b/0x12f [ 3465.914740] [<ffffffff8133d6a8>] scsi_scan_channel.part.2+0x57/0x72 [ 3465.914748] [<ffffffff8133d9b2>] scsi_scan_host_selected+0x109/0x191 [ 3465.914756] [<ffffffff8133daaf>] ? do_scsi_scan_host+0x75/0x75 [ 3465.914764] [<ffffffff8133daaa>] do_scsi_scan_host+0x70/0x75 [ 3465.914771] [<ffffffff8133dad2>] do_scan_async+0x23/0x142 [ 3465.914779] [<ffffffff8133daaf>] ? do_scsi_scan_host+0x75/0x75 [ 3465.914786] [<ffffffff8133daaf>] ? do_scsi_scan_host+0x75/0x75 [ 3465.914795] [<ffffffff810745e1>] kthread+0xa8/0xb0 [ 3465.914807] [<ffffffff814fb324>] kernel_thread_helper+0x4/0x10 [ 3465.914816] [<ffffffff814f39d4>] ? retint_restore_args+0x13/0x13 [ 3465.914824] [<ffffffff81074539>] ? __init_kthread_worker+0x5a/0x5a [ 3465.914832] [<ffffffff814fb320>] ? gs_change+0x13/0x13
Following fix is in Jens's block tree "for-linus" branch. commit 3181faa85bda3dc3f5e630a1846526c9caaa38e3 Author: Shaohua Li <shaohua.li> Date: Mon Jun 27 09:03:47 2011 +0200 cfq-iosched: fix a rcu warning I got a rcu warnning at boot. the ioc->ioc_data is rcu_deferenced, but doesn't hold rcu_read_lock. This is yet to make its way into linus's tree.
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=3181faa85bda3dc3f5e630a1846526c9caaa38e3