====================================================== WARNING: possible circular locking dependency detected 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 Not tainted ------------------------------------------------------ syz.2.428/7020 is trying to acquire lock: ffffaf80126ab988 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove fs/kernfs/dir.c:1549 [inline] ffffaf80126ab988 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove+0x34/0x58 fs/kernfs/dir.c:1540 but task is already holding lock: ffffaf8019f0c520 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:205 [inline] ffffaf8019f0c520 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x374/0x10b8 block/blk-mq.c:5060 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->q_usage_counter(io)#19){++++}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1ac/0x448 kernel/locking/lockdep.c:5825 blk_alloc_queue+0x5ae/0x6c6 block/blk-core.c:461 blk_mq_alloc_queue+0x168/0x25c block/blk-mq.c:4400 __blk_mq_alloc_disk+0x2a/0x118 block/blk-mq.c:4447 nbd_dev_add+0x45c/0xb2e drivers/block/nbd.c:1943 nbd_init+0x3f4/0x41a drivers/block/nbd.c:2680 do_one_initcall+0x1a2/0xae4 init/main.c:1269 do_initcall_level init/main.c:1331 [inline] do_initcalls init/main.c:1347 [inline] do_basic_setup init/main.c:1366 [inline] kernel_init_freeable+0x6e4/0x7a4 init/main.c:1579 kernel_init+0x28/0x24c init/main.c:1469 ret_from_fork_kernel+0x2a/0xbb4 arch/riscv/kernel/process.c:214 ret_from_fork_kernel_asm+0x16/0x18 arch/riscv/kernel/entry.S:327 -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1ac/0x448 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4234 [inline] fs_reclaim_acquire+0xd0/0x106 mm/page_alloc.c:4248 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4131 [inline] slab_alloc_node mm/slub.c:4209 [inline] kmem_cache_alloc_lru_noprof+0x4e/0x3c6 mm/slub.c:4248 alloc_inode+0xd2/0x210 fs/inode.c:348 iget_locked+0x2c2/0x7a0 fs/inode.c:1438 kernfs_get_inode+0x46/0x3f8 fs/kernfs/inode.c:253 kernfs_fill_super fs/kernfs/mount.c:307 [inline] kernfs_get_tree+0x542/0x9d8 fs/kernfs/mount.c:391 sysfs_get_tree+0x3a/0x12c fs/sysfs/mount.c:31 vfs_get_tree+0x7e/0x318 fs/super.c:1815 do_new_mount fs/namespace.c:3805 [inline] path_mount+0x6c8/0x1be4 fs/namespace.c:4120 do_mount fs/namespace.c:4133 [inline] __do_sys_mount fs/namespace.c:4344 [inline] __se_sys_mount fs/namespace.c:4321 [inline] __riscv_sys_mount+0x5e0/0x776 fs/namespace.c:4321 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:343 handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197 -> #0 (&root->kernfs_rwsem){++++}-{4:4}: check_noncircular+0x132/0x146 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x12b2/0x24ea kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1ac/0x448 kernel/locking/lockdep.c:5825 down_write+0x9c/0x19a kernel/locking/rwsem.c:1590 kernfs_remove fs/kernfs/dir.c:1549 [inline] kernfs_remove+0x34/0x58 fs/kernfs/dir.c:1540 sysfs_remove_dir+0xc8/0x10e fs/sysfs/dir.c:101 __kobject_del+0xe0/0x202 lib/kobject.c:604 kobject_del lib/kobject.c:627 [inline] kobject_del+0x42/0x66 lib/kobject.c:619 elv_unregister_queue block/elevator.c:503 [inline] elevator_change_done+0x46e/0x55e block/elevator.c:646 elevator_change+0x298/0x4d4 block/elevator.c:694 elevator_set_none+0xa8/0x126 block/elevator.c:781 blk_mq_elv_switch_none block/blk-mq.c:5023 [inline] __blk_mq_update_nr_hw_queues+0x504/0x10b8 block/blk-mq.c:5068 blk_mq_update_nr_hw_queues+0x42/0x66 block/blk-mq.c:5119 nbd_start_device+0x170/0xba8 drivers/block/nbd.c:1478 nbd_genl_connect+0xc1a/0x1b86 drivers/block/nbd.c:2228 genl_family_rcv_msg_doit+0x206/0x2e6 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x514/0x78e net/netlink/genetlink.c:1210 netlink_rcv_skb+0x206/0x3be net/netlink/af_netlink.c:2552 genl_rcv+0x36/0x4c net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x544/0x88a net/netlink/af_netlink.c:1346 netlink_sendmsg+0x860/0xdd8 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg+0xcc/0x160 net/socket.c:729 ____sys_sendmsg+0x63e/0x79c net/socket.c:2614 ___sys_sendmsg+0x144/0x1e6 net/socket.c:2668 __sys_sendmsg+0x188/0x246 net/socket.c:2700 __do_sys_sendmsg net/socket.c:2705 [inline] __se_sys_sendmsg net/socket.c:2703 [inline] __riscv_sys_sendmsg+0x70/0xa2 net/socket.c:2703 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:343 handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197 other info that might help us debug this: Chain exists of: &root->kernfs_rwsem --> fs_reclaim --> &q->q_usage_counter(io)#19 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#19); lock(fs_reclaim); lock(&q->q_usage_counter(io)#19); lock(&root->kernfs_rwsem); *** DEADLOCK *** 6 locks held by syz.2.428/7020: #0: ffffffff8992d570 (cb_lock){++++}-{4:4}, at: genl_rcv+0x28/0x4c net/netlink/genetlink.c:1218 #1: ffffffff8992d4a8 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline] #1: ffffffff8992d4a8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline] #1: ffffffff8992d4a8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:57 [inline] #1: ffffffff8992d4a8 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x532/0x78e net/netlink/genetlink.c:1209 #2: ffffaf801a09d188 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x2a/0x66 block/blk-mq.c:5117 #3: ffffaf801a09d0d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0x3a/0x66 block/blk-mq.c:5118 #4: ffffaf8019f0c520 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:205 [inline] #4: ffffaf8019f0c520 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x374/0x10b8 block/blk-mq.c:5060 #5: ffffaf8019f0c558 (&q->q_usage_counter(queue)){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:205 [inline] #5: ffffaf8019f0c558 (&q->q_usage_counter(queue)){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x374/0x10b8 block/blk-mq.c:5060 stack backtrace: CPU: 0 UID: 0 PID: 7020 Comm: syz.2.428 Not tainted 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 PREEMPT Hardware name: riscv-virtio,qemu (DT) Call Trace: [] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:132 [] show_stack+0x30/0x3c arch/riscv/kernel/stacktrace.c:138 [] __dump_stack lib/dump_stack.c:94 [inline] [] dump_stack_lvl+0x12e/0x1a6 lib/dump_stack.c:120 [] dump_stack+0x1c/0x24 lib/dump_stack.c:129 [] print_circular_bug+0x254/0x29a kernel/locking/lockdep.c:2043 [] check_noncircular+0x132/0x146 kernel/locking/lockdep.c:2175 [] check_prev_add kernel/locking/lockdep.c:3165 [inline] [] check_prevs_add kernel/locking/lockdep.c:3284 [inline] [] validate_chain kernel/locking/lockdep.c:3908 [inline] [] __lock_acquire+0x12b2/0x24ea kernel/locking/lockdep.c:5237 [] lock_acquire kernel/locking/lockdep.c:5868 [inline] [] lock_acquire+0x1ac/0x448 kernel/locking/lockdep.c:5825 [] down_write+0x9c/0x19a kernel/locking/rwsem.c:1590 [] kernfs_remove fs/kernfs/dir.c:1549 [inline] [] kernfs_remove+0x34/0x58 fs/kernfs/dir.c:1540 [] sysfs_remove_dir+0xc8/0x10e fs/sysfs/dir.c:101 [] __kobject_del+0xe0/0x202 lib/kobject.c:604 [] kobject_del lib/kobject.c:627 [inline] [] kobject_del+0x42/0x66 lib/kobject.c:619 [] elv_unregister_queue block/elevator.c:503 [inline] [] elevator_change_done+0x46e/0x55e block/elevator.c:646 [] elevator_change+0x298/0x4d4 block/elevator.c:694 [] elevator_set_none+0xa8/0x126 block/elevator.c:781 [] blk_mq_elv_switch_none block/blk-mq.c:5023 [inline] [] __blk_mq_update_nr_hw_queues+0x504/0x10b8 block/blk-mq.c:5068 [] blk_mq_update_nr_hw_queues+0x42/0x66 block/blk-mq.c:5119 [] nbd_start_device+0x170/0xba8 drivers/block/nbd.c:1478 [] nbd_genl_connect+0xc1a/0x1b86 drivers/block/nbd.c:2228 [] genl_family_rcv_msg_doit+0x206/0x2e6 net/netlink/genetlink.c:1115 [] genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] [] genl_rcv_msg+0x514/0x78e net/netlink/genetlink.c:1210 [] netlink_rcv_skb+0x206/0x3be net/netlink/af_netlink.c:2552 [] genl_rcv+0x36/0x4c net/netlink/genetlink.c:1219 [] netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] [] netlink_unicast+0x544/0x88a net/netlink/af_netlink.c:1346 [] netlink_sendmsg+0x860/0xdd8 net/netlink/af_netlink.c:1896 [] sock_sendmsg_nosec net/socket.c:714 [inline] [] __sock_sendmsg+0xcc/0x160 net/socket.c:729 [] ____sys_sendmsg+0x63e/0x79c net/socket.c:2614 [] ___sys_sendmsg+0x144/0x1e6 net/socket.c:2668 [] __sys_sendmsg+0x188/0x246 net/socket.c:2700 [] __do_sys_sendmsg net/socket.c:2705 [inline] [] __se_sys_sendmsg net/socket.c:2703 [inline] [] __riscv_sys_sendmsg+0x70/0xa2 net/socket.c:2703 [] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 [] do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:343 [] handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197 nbd0: detected capacity change from 0 to 32