====================================================== WARNING: possible circular locking dependency detected 6.12.0-syzkaller-03657-g43fb83c17ba2 #0 Not tainted ------------------------------------------------------ kworker/0:6/6021 is trying to acquire lock: ffff888024390fa0 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_unregister_queue+0x125/0x2e0 block/blk-sysfs.c:869 but task is already holding lock: ffff888024391030 (&q->sysfs_dir_lock){+.+.}-{4:4}, at: blk_unregister_queue+0xdb/0x2e0 block/blk-sysfs.c:860 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&q->sysfs_dir_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 blk_mq_sysfs_unregister_hctxs+0x92/0x2d0 block/blk-mq-sysfs.c:278 __blk_mq_update_nr_hw_queues+0x93f/0x1460 block/blk-mq.c:4930 blk_mq_update_nr_hw_queues+0x2a/0x40 block/blk-mq.c:4985 nbd_start_device+0x15b/0xd70 drivers/block/nbd.c:1413 nbd_start_device_ioctl drivers/block/nbd.c:1464 [inline] __nbd_ioctl drivers/block/nbd.c:1539 [inline] nbd_ioctl+0x21a/0xfd0 drivers/block/nbd.c:1579 compat_blkdev_ioctl+0x2f7/0x750 block/ioctl.c:749 __do_compat_sys_ioctl+0x1cb/0x2c0 fs/ioctl.c:1004 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #4 (&q->q_usage_counter(io)#53){++++}-{0:0}: bio_queue_enter block/blk.h:75 [inline] blk_mq_submit_bio+0x1fc4/0x24c0 block/blk-mq.c:3092 __submit_bio+0x384/0x540 block/blk-core.c:629 __submit_bio_noacct_mq block/blk-core.c:710 [inline] submit_bio_noacct_nocheck+0x6fb/0xd70 block/blk-core.c:739 submit_bio_noacct+0x93a/0x1e10 block/blk-core.c:868 submit_bh fs/buffer.c:2825 [inline] block_read_full_folio+0x812/0xa50 fs/buffer.c:2452 filemap_read_folio+0xc6/0x2a0 mm/filemap.c:2367 filemap_update_page mm/filemap.c:2451 [inline] filemap_get_pages+0x1560/0x1be0 mm/filemap.c:2572 filemap_read+0x3ca/0xd70 mm/filemap.c:2647 blkdev_read_iter+0x187/0x480 block/fops.c:767 new_sync_read fs/read_write.c:484 [inline] vfs_read+0x87f/0xbe0 fs/read_write.c:565 ksys_read+0x12b/0x250 fs/read_write.c:708 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (mapping.invalidate_lock#2){++++}-{4:4}: down_read+0x9a/0x330 kernel/locking/rwsem.c:1524 filemap_invalidate_lock_shared include/linux/fs.h:873 [inline] filemap_fault+0x62e/0x2820 mm/filemap.c:3352 __do_fault+0x10a/0x490 mm/memory.c:4882 do_read_fault mm/memory.c:5297 [inline] do_fault mm/memory.c:5431 [inline] do_pte_missing+0xec5/0x3e70 mm/memory.c:3965 handle_pte_fault mm/memory.c:5766 [inline] __handle_mm_fault+0x100a/0x2a10 mm/memory.c:5909 handle_mm_fault+0x3fa/0xaa0 mm/memory.c:6077 faultin_page mm/gup.c:1187 [inline] __get_user_pages+0x8d9/0x3b50 mm/gup.c:1485 populate_vma_page_range+0x27f/0x3a0 mm/gup.c:1923 __mm_populate+0x1d6/0x380 mm/gup.c:2026 do_mlock+0x40a/0x7d0 mm/mlock.c:653 __do_sys_mlock mm/mlock.c:661 [inline] __se_sys_mlock mm/mlock.c:659 [inline] __ia32_sys_mlock+0x57/0x80 mm/mlock.c:659 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #2 (&mm->mmap_lock){++++}-{4:4}: __might_fault mm/memory.c:6716 [inline] __might_fault+0x11b/0x190 mm/memory.c:6709 _inline_copy_from_user include/linux/uaccess.h:162 [inline] _copy_from_user+0x29/0xd0 lib/usercopy.c:18 copy_from_user include/linux/uaccess.h:212 [inline] compat_blk_trace_setup+0xc9/0x200 kernel/trace/blktrace.c:664 blk_trace_ioctl+0x24a/0x290 kernel/trace/blktrace.c:745 compat_blkdev_ioctl+0x13c/0x750 block/ioctl.c:742 __do_compat_sys_ioctl+0x1cb/0x2c0 fs/ioctl.c:1004 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (&q->debugfs_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 blk_register_queue+0x13c/0x550 block/blk-sysfs.c:774 add_disk_fwnode+0x785/0x1300 block/genhd.c:493 add_disk include/linux/blkdev.h:751 [inline] brd_alloc.isra.0+0x50a/0x7c0 drivers/block/brd.c:399 brd_init+0x12b/0x1d0 drivers/block/brd.c:479 do_one_initcall+0x128/0x630 init/main.c:1266 do_initcall_level init/main.c:1328 [inline] do_initcalls init/main.c:1344 [inline] do_basic_setup init/main.c:1363 [inline] kernel_init_freeable+0x58f/0x8b0 init/main.c:1577 kernel_init+0x1c/0x2b0 init/main.c:1466 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #0 (&q->sysfs_lock){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 blk_unregister_queue+0x125/0x2e0 block/blk-sysfs.c:869 del_gendisk+0x2df/0xae0 block/genhd.c:710 md_kobj_release+0xb2/0x100 drivers/md/md.c:5742 kobject_cleanup lib/kobject.c:689 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1e4/0x5a0 lib/kobject.c:737 process_one_work+0x958/0x1b30 kernel/workqueue.c:3229 process_scheduled_works kernel/workqueue.c:3310 [inline] worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 other info that might help us debug this: Chain exists of: &q->sysfs_lock --> &q->q_usage_counter(io)#53 --> &q->sysfs_dir_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->sysfs_dir_lock); lock(&q->q_usage_counter(io)#53); lock(&q->sysfs_dir_lock); lock(&q->sysfs_lock); *** DEADLOCK *** 3 locks held by kworker/0:6/6021: #0: ffff888040583d48 ((wq_completion)md_misc){+.+.}-{0:0}, at: process_one_work+0x1212/0x1b30 kernel/workqueue.c:3204 #1: ffffc9000457fd80 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}, at: process_one_work+0x8bb/0x1b30 kernel/workqueue.c:3205 #2: ffff888024391030 (&q->sysfs_dir_lock){+.+.}-{4:4}, at: blk_unregister_queue+0xdb/0x2e0 block/blk-sysfs.c:860 stack backtrace: CPU: 0 UID: 0 PID: 6021 Comm: kworker/0:6 Not tainted 6.12.0-syzkaller-03657-g43fb83c17ba2 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: md_misc mddev_delayed_delete Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x41c/0x610 kernel/locking/lockdep.c:2074 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206 check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 blk_unregister_queue+0x125/0x2e0 block/blk-sysfs.c:869 del_gendisk+0x2df/0xae0 block/genhd.c:710 md_kobj_release+0xb2/0x100 drivers/md/md.c:5742 kobject_cleanup lib/kobject.c:689 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1e4/0x5a0 lib/kobject.c:737 process_one_work+0x958/0x1b30 kernel/workqueue.c:3229 process_scheduled_works kernel/workqueue.c:3310 [inline] worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244