====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ kworker/3:4/5828 is trying to acquire lock: ffff8880293f4358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: mddev_lock_nointr drivers/md/md.h:735 [inline] ffff8880293f4358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: md_start_sync+0x79/0xbe0 drivers/md/md.c:10190 but task is already holding lock: ffffc900067e7d08 ((work_completion)(&mddev->sync_work)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 ((work_completion)(&mddev->sync_work)){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 process_one_work+0x98e/0x1940 kernel/workqueue.c:3298 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #2 ((wq_completion)md_misc){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 touch_wq_lockdep_map+0xad/0x1c0 kernel/workqueue.c:4037 __flush_workqueue+0x131/0x1200 kernel/workqueue.c:4079 md_alloc+0x30/0x10a0 drivers/md/md.c:6313 md_alloc_and_put drivers/md/md.c:6402 [inline] md_probe drivers/md/md.c:6418 [inline] md_probe+0x73/0xf0 drivers/md/md.c:6413 blk_probe_dev+0x149/0x1e0 block/genhd.c:880 blk_request_module+0x16/0xc0 block/genhd.c:893 blkdev_get_no_open+0x9b/0xf0 block/bdev.c:828 blkdev_open+0x141/0x4f0 block/fops.c:663 do_dentry_open+0x6ab/0x14d0 fs/open.c:947 vfs_open+0x82/0x3f0 fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x2873/0x4280 fs/namei.c:4863 do_file_open+0x20e/0x430 fs/namei.c:4892 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_compat_sys_openat fs/open.c:1436 [inline] __se_compat_sys_openat fs/open.c:1434 [inline] __ia32_compat_sys_openat+0x12d/0x210 fs/open.c:1434 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (major_names_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 blk_probe_dev+0x28/0x1e0 block/genhd.c:877 blk_request_module+0x16/0xc0 block/genhd.c:893 blkdev_get_no_open+0x9b/0xf0 block/bdev.c:828 bdev_file_open_by_dev block/bdev.c:1049 [inline] bdev_file_open_by_dev+0x70/0x210 block/bdev.c:1037 md_import_device+0x120/0x360 drivers/md/md.c:3845 md_add_new_disk+0xdbf/0x1820 drivers/md/md.c:7637 md_ioctl+0x2b28/0x36b0 drivers/md/md.c:8476 compat_blkdev_ioctl+0x682/0x7b0 block/ioctl.c:853 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __ia32_compat_sys_ioctl+0x2cf/0x360 fs/ioctl.c:638 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (&mddev->reconfig_mutex){+.+.}-{4:4}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 mddev_lock_nointr drivers/md/md.h:735 [inline] md_start_sync+0x79/0xbe0 drivers/md/md.c:10190 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Chain exists of: &mddev->reconfig_mutex --> (wq_completion)md_misc --> (work_completion)(&mddev->sync_work) Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((work_completion)(&mddev->sync_work)); lock((wq_completion)md_misc); lock((work_completion)(&mddev->sync_work)); lock(&mddev->reconfig_mutex); *** DEADLOCK *** 2 locks held by kworker/3:4/5828: #0: ffff88802177c140 ((wq_completion)md_misc){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc900067e7d08 ((work_completion)(&mddev->sync_work)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 stack backtrace: CPU: 3 UID: 0 PID: 5828 Comm: kworker/3:4 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: md_misc md_start_sync Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 mddev_lock_nointr drivers/md/md.h:735 [inline] md_start_sync+0x79/0xbe0 drivers/md/md.c:10190 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245