From: Christof Schmitt <christof.schmitt@xxxxxxxxxx> Testing with request based dm multipathing and lock dependency checking revealed this problem. Fix this by disabling interrupts when acquiring the map_lock from the ioctl call in __bind and __unbind. It seems that the problem has been introduced with this patch: http://lkml.indiana.edu/hypermail/linux/kernel/0810.0/1067.html ====================================================== [ INFO: soft-safe -> soft-unsafe lock order detected ] 2.6.27.13-1.1.mz11dbg-default #1 ------------------------------------------------------ multipath/3857 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: (&md->map_lock){----}, at: [<000003e000573a0e>] dm_get_table+0x32/0x68 [dm_mod] and this task is already holding: (&q->__queue_lock){.+..}, at: [<000003e000573b04>] dm_resume+0xc0/0x1b8 [dm_mod] which would create a new lock dependency: (&q->__queue_lock){.+..} -> (&md->map_lock){----} but this new dependency connects a soft-irq-safe lock: (&q->__queue_lock){.+..} ... which became soft-irq-safe at: [<00000000001633fa>] mark_irqflags+0xa6/0x154 [<0000000000165486>] __lock_acquire+0x5ea/0x780 [<0000000000165686>] lock_acquire+0x6a/0x90 [<00000000003b5f8a>] _spin_lock+0x4a/0x64 [<000003e000786fd2>] scsi_device_unbusy+0xb2/0xe4 [scsi_mod] [<000003e00077def4>] scsi_finish_command+0x4c/0x11c [scsi_mod] [<000003e000787278>] scsi_softirq_done+0x170/0x180 [scsi_mod] [<00000000002a4c2a>] blk_done_softirq+0xc6/0xe4 [<000000000013c9d2>] __do_softirq+0xee/0x1ec [<000000000010fcc8>] do_softirq+0x9c/0xd8 [<000000000013c3e6>] irq_exit+0x82/0xe0 [<00000000002fda4c>] do_IRQ+0x170/0x190 [<0000000000113c36>] io_return+0x0/0x8 [<0000000000109c10>] default_idle+0x198/0x1a8 to a soft-irq-unsafe lock: (&md->map_lock){----} ... which became soft-irq-unsafe at: ... [<0000000000163478>] mark_irqflags+0x124/0x154 [<0000000000165486>] __lock_acquire+0x5ea/0x780 [<0000000000165686>] lock_acquire+0x6a/0x90 [<00000000003b6146>] _write_lock+0x4a/0x64 [<000003e000572a1a>] __bind+0x116/0x184 [dm_mod] [<000003e000572b18>] dm_swap_table+0x90/0xb8 [dm_mod] [<000003e0005791e4>] do_resume+0xe4/0x17c [dm_mod] [<000003e00057932e>] dev_suspend+0xb2/0xc8 [dm_mod] [<000003e000579f46>] ctl_ioctl+0x236/0x2ac [dm_mod] [<000003e000579fea>] dm_ctl_ioctl+0x2e/0x40 [dm_mod] [<00000000001e7764>] vfs_ioctl+0x50/0xbc [<00000000001e7c64>] do_vfs_ioctl+0x26c/0x280 [<00000000001e7d4e>] SyS_ioctl+0xd6/0xfc [<0000000000113696>] sysc_noemu+0x10/0x16 [<000002000019269e>] 0x2000019269e [...] stack backtrace: CPU: 3 Not tainted 2.6.27.13-1.1.mz11dbg-default #1 Process multipath (pid: 3857, task: 0000000139e06038, ksp: 000000013416b858) 0000000139e067d0 000000013416b708 0000000000000002 0000000000000000 000000013416b7a8 000000013416b720 000000013416b720 0000000000104c3e 0000000000000003 0000000000000000 0000000000000000 000000010000000b 0000000000000060 0000000000000008 000000013416b708 000000013416b778 00000000003ba8b8 0000000000104c3e 000000013416b708 000000013416b760 Call Trace: ([<0000000000104b86>] show_trace+0xb2/0xd0) [<0000000000104c5c>] show_stack+0xb8/0xc8 [<00000000003b2392>] dump_stack+0xae/0xbc [<00000000001640ec>] print_bad_irq_dependency+0x320/0x334 [<0000000000164226>] check_usage+0x126/0x138 [<0000000000164368>] check_prev_add+0x130/0x530 [<0000000000164d3a>] validate_chain+0x5d2/0x734 [<00000000001655aa>] __lock_acquire+0x70e/0x780 [<0000000000165686>] lock_acquire+0x6a/0x90 [<00000000003b645a>] _read_lock+0x4a/0x64 [<000003e000573a0e>] dm_get_table+0x32/0x68 [dm_mod] [<000003e000574b9a>] dm_request_fn+0x3e/0x1a4 [dm_mod] [<000000000029f1ac>] blk_invoke_request_fn+0x94/0x170 [<000000000029f304>] blk_start_queue+0x7c/0x9c [<000003e000573b20>] dm_resume+0xdc/0x1b8 [dm_mod] [<000003e00057924a>] do_resume+0x14a/0x17c [dm_mod] [<000003e00057932e>] dev_suspend+0xb2/0xc8 [dm_mod] [<000003e000579f46>] ctl_ioctl+0x236/0x2ac [dm_mod] [<000003e000579fea>] dm_ctl_ioctl+0x2e/0x40 [dm_mod] [<00000000001e7764>] vfs_ioctl+0x50/0xbc [<00000000001e7c64>] do_vfs_ioctl+0x26c/0x280 [<00000000001e7d4e>] SyS_ioctl+0xd6/0xfc [<0000000000113696>] sysc_noemu+0x10/0x16 [<000002000019269e>] 0x2000019269e INFO: lockdep is turned off. Signed-off-by: Christof Schmitt <christof.schmitt@xxxxxxxxxx> --- linux-2.6.27.13-1.orig/drivers/md/dm.c +++ linux-2.6.27.13-1/drivers/md/dm.c @@ -1943,7 +1943,7 @@ static int __bind(struct mapped_device * if (dm_table_request_based(t) && !blk_queue_stopped(q)) stop_queue(q); - write_lock(&md->map_lock); + write_lock_irq(&md->map_lock); md->map = t; dm_table_set_restrictions(t, q); dm_table_set_integrity(t, md); @@ -1952,7 +1952,7 @@ static int __bind(struct mapped_device * } else { set_disk_ro(md->disk, 0); } - write_unlock(&md->map_lock); + write_unlock_irq(&md->map_lock); return 0; } @@ -1965,9 +1965,9 @@ static void __unbind(struct mapped_devic return; dm_table_event_callback(map, NULL, NULL); - write_lock(&md->map_lock); + write_lock_irq(&md->map_lock); md->map = NULL; - write_unlock(&md->map_lock); + write_unlock_irq(&md->map_lock); dm_table_destroy(map); } -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
