====================================================== WARNING: possible circular locking dependency detected 6.12.0-syzkaller-08446-g228a1157fb9f #0 Not tainted ------------------------------------------------------ syz.4.2621/16430 is trying to acquire lock: ffff888144b8acf8 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_mq_elv_switch_none block/blk-mq.c:4847 [inline] ffff888144b8acf8 (&q->sysfs_lock){+.+.}-{4:4}, at: __blk_mq_update_nr_hw_queues+0x446/0x14e0 block/blk-mq.c:4925 but task is already holding lock: ffff888144b8a7c8 (&q->q_usage_counter(io)#53){++++}-{0:0}, at: blk_mq_freeze_queue block/blk-mq.c:212 [inline] ffff888144b8a7c8 (&q->q_usage_counter(io)#53){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x1fc/0x14e0 block/blk-mq.c:4918 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&q->q_usage_counter(io)#53){++++}-{0:0}: bio_queue_enter block/blk.h:75 [inline] blk_mq_submit_bio+0x1fb6/0x24c0 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+0x698/0xd70 block/blk-core.c:739 submit_bio_noacct+0x93a/0x1e20 block/blk-core.c:868 submit_bh fs/buffer.c:2824 [inline] block_read_full_folio+0x812/0xa50 fs/buffer.c:2451 filemap_read_folio+0xc6/0x2a0 mm/filemap.c:2367 filemap_update_page mm/filemap.c:2451 [inline] filemap_get_pages+0x155f/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+0x62c/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 do_user_addr_fault+0x7a3/0x13f0 arch/x86/mm/fault.c:1389 handle_page_fault arch/x86/mm/fault.c:1481 [inline] exc_page_fault+0x5c/0xc0 arch/x86/mm/fault.c:1539 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 rep_movs_alternative+0x30/0x70 arch/x86/lib/copy_user_64.S:50 copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline] raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline] _inline_copy_from_user include/linux/uaccess.h:178 [inline] _copy_from_user+0x9a/0xd0 lib/usercopy.c:18 copy_from_user include/linux/uaccess.h:212 [inline] move_addr_to_kernel+0x68/0x160 net/socket.c:252 __sys_connect+0xb0/0x170 net/socket.c:2070 __do_sys_connect net/socket.c:2080 [inline] __se_sys_connect net/socket.c:2077 [inline] __x64_sys_connect+0x72/0xb0 net/socket.c:2077 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 -> #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] __blk_trace_setup+0xa8/0x180 kernel/trace/blktrace.c:626 blk_trace_ioctl+0x163/0x290 kernel/trace/blktrace.c:740 blkdev_ioctl+0x109/0x6d0 block/ioctl.c:682 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892 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 -> #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+0x5a2/0x840 drivers/block/brd.c:399 brd_init+0x12b/0x1d0 drivers/block/brd.c:479 do_one_initcall+0x128/0x700 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+0x5c7/0x900 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_mq_elv_switch_none block/blk-mq.c:4847 [inline] __blk_mq_update_nr_hw_queues+0x446/0x14e0 block/blk-mq.c:4925 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 blkdev_ioctl+0x276/0x6d0 block/ioctl.c:693 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892 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 other info that might help us debug this: Chain exists of: &q->sysfs_lock --> mapping.invalidate_lock#2 --> &q->q_usage_counter(io)#53 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#53); lock(mapping.invalidate_lock#2); lock(&q->q_usage_counter(io)#53); lock(&q->sysfs_lock); *** DEADLOCK *** 4 locks held by syz.4.2621/16430: #0: ffff888025ad5998 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_ioctl+0x151/0xfd0 drivers/block/nbd.c:1572 #1: ffff888025ad58d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0x20/0x40 block/blk-mq.c:4984 #2: ffff888144b8a7c8 (&q->q_usage_counter(io)#53){++++}-{0:0}, at: blk_mq_freeze_queue block/blk-mq.c:212 [inline] #2: ffff888144b8a7c8 (&q->q_usage_counter(io)#53){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x1fc/0x14e0 block/blk-mq.c:4918 #3: ffff888144b8a800 (&q->q_usage_counter(queue)#37){+.+.}-{0:0}, at: blk_mq_freeze_queue block/blk-mq.c:212 [inline] #3: ffff888144b8a800 (&q->q_usage_counter(queue)#37){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x1fc/0x14e0 block/blk-mq.c:4918 stack backtrace: CPU: 0 UID: 0 PID: 16430 Comm: syz.4.2621 Not tainted 6.12.0-syzkaller-08446-g228a1157fb9f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x419/0x5d0 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_mq_elv_switch_none block/blk-mq.c:4847 [inline] __blk_mq_update_nr_hw_queues+0x446/0x14e0 block/blk-mq.c:4925 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 blkdev_ioctl+0x276/0x6d0 block/ioctl.c:693 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892 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 RIP: 0033:0x7ff661f7e819 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff662d79038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ff662135fa0 RCX: 00007ff661f7e819 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000006 RBP: 00007ff661ff175e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ff662135fa0 R15: 00007ffd325a42c8 block nbd4: shutting down sockets