On Thu, 2006-09-28 at 13:54 +0200, Michal Piotrowski wrote: > Hi, > > On 28/09/06, Andrew Morton <akpm@xxxxxxxx> wrote: > > > > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.18/2.6.18-mm2/ > > > > > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.18-mm2 #1 > ------------------------------------------------------- > nash/1264 is trying to acquire lock: > (&bdev_part_lock_key){--..}, at: [<c0310d4a>] mutex_lock+0x1c/0x1f > > but task is already holding lock: > (&new->reconfig_mutex){--..}, at: [<c03108ff>] > mutex_lock_interruptible+0x1c/0x1f > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #2 (&new->reconfig_mutex){--..}: > [<c01390b8>] add_lock_to_list+0x5c/0x7a > [<c013b1dd>] __lock_acquire+0x9f3/0xaef > [<c013b643>] lock_acquire+0x71/0x91 > [<c031068f>] __mutex_lock_interruptible_slowpath+0xd2/0x326 > [<c03108ff>] mutex_lock_interruptible+0x1c/0x1f > [<c02ba4e3>] md_open+0x28/0x5d -> mddev->reconfig_mutex > [<c0197853>] do_open+0x8b/0x377 -> bdev->bd_mutex (whole) > [<c0197cd5>] blkdev_open+0x1d/0x46 > [<c0172f36>] __dentry_open+0x133/0x260 > [<c01730d1>] nameidata_to_filp+0x1c/0x2e > [<c0173111>] do_filp_open+0x2e/0x35 > [<c0173170>] do_sys_open+0x58/0xde > [<c0173222>] sys_open+0x16/0x18 > [<c0103297>] syscall_call+0x7/0xb > [<ffffffff>] 0xffffffff > > -> #1 (&bdev->bd_mutex){--..}: > [<c01390b8>] add_lock_to_list+0x5c/0x7a > [<c013b1dd>] __lock_acquire+0x9f3/0xaef > [<c013b643>] lock_acquire+0x71/0x91 > [<c0310b0f>] __mutex_lock_slowpath+0xd2/0x2f1 > [<c0310d4a>] mutex_lock+0x1c/0x1f > [<c0197824>] do_open+0x5c/0x377 > [<c0197bab>] blkdev_get+0x6c/0x77 > [<c01978d0>] do_open+0x108/0x377 > [<c0197bab>] blkdev_get+0x6c/0x77 > [<c0197eb1>] open_by_devnum+0x30/0x3c > [<c0147419>] swsusp_check+0x14/0xc5 > [<c0145865>] software_resume+0x7e/0x100 > [<c010049e>] init+0x121/0x29f > [<c0103f23>] kernel_thread_helper+0x7/0x10 > [<c0109523>] save_stack_trace+0x17/0x30 > [<c0138fb0>] save_trace+0x4f/0xfb > [<c01390b8>] add_lock_to_list+0x5c/0x7a > [<c013b1dd>] __lock_acquire+0x9f3/0xaef > [<c013b643>] lock_acquire+0x71/0x91 > [<c0310b0f>] __mutex_lock_slowpath+0xd2/0x2f1 > [<c0310d4a>] mutex_lock+0x1c/0x1f > [<c0197824>] do_open+0x5c/0x377 -> bdev->bd_mutex (whole) > [<c0197bab>] blkdev_get+0x6c/0x77 > [<c01978d0>] do_open+0x108/0x377 -> bdev->bd_mutex (partition) > [<c0197bab>] blkdev_get+0x6c/0x77 > [<c0197eb1>] open_by_devnum+0x30/0x3c > [<c0147419>] swsusp_check+0x14/0xc5 > [<c0145865>] software_resume+0x7e/0x100 > [<c010049e>] init+0x121/0x29f > [<c0103f23>] kernel_thread_helper+0x7/0x10 > [<ffffffff>] 0xffffffff > > -> #0 (&bdev_part_lock_key){--..}: > [<c013a7b6>] print_circular_bug_tail+0x30/0x64 > [<c013b114>] __lock_acquire+0x92a/0xaef > [<c013b643>] lock_acquire+0x71/0x91 > [<c0310b0f>] __mutex_lock_slowpath+0xd2/0x2f1 > [<c0310d4a>] mutex_lock+0x1c/0x1f > [<c0197323>] bd_claim_by_disk+0x5f/0x18e -> bdev->bd_mutex (partition) > [<c02b44ec>] bind_rdev_to_array+0x1f0/0x20e > [<c02b6453>] autostart_arrays+0x24b/0x322 > [<c02b9158>] md_ioctl+0x91/0x13f4 > [<c01ea5bc>] blkdev_driver_ioctl+0x49/0x5b > [<c01ead23>] blkdev_ioctl+0x755/0x7a2 > [<c0196f9d>] block_ioctl+0x16/0x1b > [<c01801d2>] do_ioctl+0x22/0x67 > [<c0180460>] vfs_ioctl+0x249/0x25c > [<c01804ba>] sys_ioctl+0x47/0x75 > [<c0103297>] syscall_call+0x7/0xb > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by nash/1264: > #0: (&new->reconfig_mutex){--..}, at: [<c03108ff>] > mutex_lock_interruptible+0x1c/0x1f > stack backtrace: > [<c0104215>] dump_trace+0x64/0x1cd > [<c0104390>] show_trace_log_lvl+0x12/0x25 > [<c01049e5>] show_trace+0xd/0x10 > [<c0104aad>] dump_stack+0x19/0x1b > [<c013a7df>] print_circular_bug_tail+0x59/0x64 > [<c013b114>] __lock_acquire+0x92a/0xaef > [<c013b643>] lock_acquire+0x71/0x91 > [<c0310b0f>] __mutex_lock_slowpath+0xd2/0x2f1 > [<c0310d4a>] mutex_lock+0x1c/0x1f > [<c0197323>] bd_claim_by_disk+0x5f/0x18e -> bdev->bd_mutex (part) > [<c02b44ec>] bind_rdev_to_array+0x1f0/0x20e autorun_devices -> mddev->reconfig_mutex > [<c02b6453>] autostart_arrays+0x24b/0x322 > [<c02b9158>] md_ioctl+0x91/0x13f4 > [<c01ea5bc>] blkdev_driver_ioctl+0x49/0x5b > [<c01ead23>] blkdev_ioctl+0x755/0x7a2 > [<c0196f9d>] block_ioctl+0x16/0x1b > [<c01801d2>] do_ioctl+0x22/0x67 > [<c0180460>] vfs_ioctl+0x249/0x25c > [<c01804ba>] sys_ioctl+0x47/0x75 > [<c0103297>] syscall_call+0x7/0xb > DWARF2 unwinder stuck at syscall_call+0x7/0xb > > Leftover inexact backtrace: Looks like a real deadlock here. It seems to me #2 is the easiest to break. static int md_open(struct inode *inode, struct file *file) { /* * Succeed if we can lock the mddev, which confirms that * it isn't being stopped right now. */ mddev_t *mddev = inode->i_bdev->bd_disk->private_data; int err; if ((err = mddev_lock(mddev))) goto out; err = 0; mddev_get(mddev); mddev_unlock(mddev); check_disk_change(inode->i_bdev); out: return err; } mddev_get() is a simple atomic_inc(), and I fail to see how waiting for the lock makes any difference. - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
