====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.144/4734 is trying to acquire lock: ffffffff88b616a8 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0xcba/0x1a96 mm/percpu.c:1782 but task is already holding lock: ffffaf801b4a0060 (&q->q_usage_counter(io)#21){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] ffffaf801b4a0060 (&q->q_usage_counter(io)#21){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5132 [inline] ffffaf801b4a0060 (&q->q_usage_counter(io)#21){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x82e/0x1300 block/blk-mq.c:5186 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->q_usage_counter(io)#21){++++}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b0/0x44e 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:4415 __blk_mq_alloc_disk+0x2a/0xe4 block/blk-mq.c:4462 nbd_dev_add+0x45c/0xb2e drivers/block/nbd.c:1954 nbd_init+0x3f6/0x41c drivers/block/nbd.c:2692 do_one_initcall+0x1a0/0xaec init/main.c:1378 do_initcall_level init/main.c:1440 [inline] do_initcalls init/main.c:1456 [inline] do_basic_setup init/main.c:1475 [inline] kernel_init_freeable+0x6e4/0x7a6 init/main.c:1688 kernel_init+0x28/0x24c init/main.c:1578 ret_from_fork_kernel+0x2a/0xc78 arch/riscv/kernel/process.c:214 ret_from_fork_kernel_asm+0x16/0x18 arch/riscv/kernel/entry.S:328 -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b0/0x44e kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4301 [inline] fs_reclaim_acquire+0xd0/0x106 mm/page_alloc.c:4315 might_alloc include/linux/sched/mm.h:317 [inline] prepare_alloc_pages+0x15e/0x564 mm/page_alloc.c:4978 __alloc_frozen_pages_noprof+0x164/0x211a mm/page_alloc.c:5199 __alloc_pages_noprof+0xe/0x22 mm/page_alloc.c:5244 __alloc_pages_node_noprof include/linux/gfp.h:285 [inline] alloc_pages_node_noprof include/linux/gfp.h:312 [inline] pcpu_alloc_pages mm/percpu-vm.c:95 [inline] pcpu_populate_chunk+0x272/0xf4e mm/percpu-vm.c:285 pcpu_alloc_noprof+0x92a/0x1a96 mm/percpu.c:1870 xt_percpu_counter_alloc+0x13a/0x194 net/netfilter/x_tables.c:1934 find_check_entry.constprop.0+0xe4/0x8a4 net/ipv4/netfilter/ip_tables.c:526 translate_table+0xc08/0x15e2 net/ipv4/netfilter/ip_tables.c:716 do_replace+0x2f8/0x44a net/ipv4/netfilter/ip_tables.c:1137 do_ipt_set_ctl+0x39e/0x916 net/ipv4/netfilter/ip_tables.c:1635 nf_setsockopt+0x78/0xda net/netfilter/nf_sockopt.c:101 ip_setsockopt+0xd2/0xe6 net/ipv4/ip_sockglue.c:1424 tcp_setsockopt+0x8e/0xe0 net/ipv4/tcp.c:4166 sock_common_setsockopt+0x90/0xc0 net/core/sock.c:3972 do_sock_setsockopt+0x20a/0x402 net/socket.c:2322 __sys_setsockopt+0x142/0x1e6 net/socket.c:2347 __do_sys_setsockopt net/socket.c:2353 [inline] __se_sys_setsockopt net/socket.c:2350 [inline] __riscv_sys_setsockopt+0xa6/0x114 net/socket.c:2350 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x3d8/0x56c arch/riscv/kernel/traps.c:343 handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:198 -> #0 (pcpu_alloc_mutex){+.+.}-{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+0x1b0/0x44e kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x16a/0x19b4 kernel/locking/mutex.c:776 _mutex_lock_killable+0x16/0x1e kernel/locking/mutex.c:844 pcpu_alloc_noprof+0xcba/0x1a96 mm/percpu.c:1782 init_alloc_hint lib/sbitmap.c:16 [inline] sbitmap_init_node+0x2b0/0x792 lib/sbitmap.c:126 sbitmap_queue_init_node+0x42/0x430 lib/sbitmap.c:454 bt_alloc block/blk-mq-tag.c:546 [inline] blk_mq_init_tags+0x164/0x2e6 block/blk-mq-tag.c:571 blk_mq_alloc_rq_map block/blk-mq.c:3546 [inline] blk_mq_alloc_map_and_rqs+0x1f4/0xe34 block/blk-mq.c:4114 __blk_mq_alloc_map_and_rqs block/blk-mq.c:4136 [inline] __blk_mq_alloc_map_and_rqs block/blk-mq.c:4127 [inline] blk_mq_realloc_tag_set_tags block/blk-mq.c:4803 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5134 [inline] blk_mq_update_nr_hw_queues+0xb14/0x1300 block/blk-mq.c:5186 nbd_start_device+0x170/0xba8 drivers/block/nbd.c:1489 nbd_start_device_ioctl drivers/block/nbd.c:1548 [inline] __nbd_ioctl drivers/block/nbd.c:1623 [inline] nbd_ioctl+0x474/0xbde drivers/block/nbd.c:1663 blkdev_ioctl+0xb2e/0x12da block/ioctl.c:791 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __riscv_sys_ioctl+0x180/0x1e4 fs/ioctl.c:583 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x3d8/0x56c arch/riscv/kernel/traps.c:343 handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:198 other info that might help us debug this: Chain exists of: pcpu_alloc_mutex --> fs_reclaim --> &q->q_usage_counter(io)#21 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#21); lock(fs_reclaim); lock(&q->q_usage_counter(io)#21); lock(pcpu_alloc_mutex); *** DEADLOCK *** 4 locks held by syz.2.144/4734: #0: ffffaf801b4981d0 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0xaa/0x1300 block/blk-mq.c:5184 #1: ffffaf801b4980d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0xd2/0x1300 block/blk-mq.c:5185 #2: ffffaf801b4a0060 (&q->q_usage_counter(io)#21){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #2: ffffaf801b4a0060 (&q->q_usage_counter(io)#21){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5132 [inline] #2: ffffaf801b4a0060 (&q->q_usage_counter(io)#21){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x82e/0x1300 block/blk-mq.c:5186 #3: ffffaf801b4a0098 (&q->q_usage_counter(queue)#5){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #3: ffffaf801b4a0098 (&q->q_usage_counter(queue)#5){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5132 [inline] #3: ffffaf801b4a0098 (&q->q_usage_counter(queue)#5){+.+.}-{0:0}, at: blk_mq_update_nr_hw_queues+0x82e/0x1300 block/blk-mq.c:5186 stack backtrace: CPU: 0 UID: 0 PID: 4734 Comm: syz.2.144 Not tainted syzkaller #0 PREEMPT Hardware name: riscv-virtio,qemu (DT) Call Trace: [] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:149 [] show_stack+0x30/0x3c arch/riscv/kernel/stacktrace.c:155 [] __dump_stack lib/dump_stack.c:94 [inline] [] dump_stack_lvl+0x12a/0x1a2 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+0x1b0/0x44e kernel/locking/lockdep.c:5825 [] __mutex_lock_common kernel/locking/mutex.c:614 [inline] [] __mutex_lock+0x16a/0x19b4 kernel/locking/mutex.c:776 [] _mutex_lock_killable+0x16/0x1e kernel/locking/mutex.c:844 [] pcpu_alloc_noprof+0xcba/0x1a96 mm/percpu.c:1782 [] init_alloc_hint lib/sbitmap.c:16 [inline] [] sbitmap_init_node+0x2b0/0x792 lib/sbitmap.c:126 [] sbitmap_queue_init_node+0x42/0x430 lib/sbitmap.c:454 [] bt_alloc block/blk-mq-tag.c:546 [inline] [] blk_mq_init_tags+0x164/0x2e6 block/blk-mq-tag.c:571 [] blk_mq_alloc_rq_map block/blk-mq.c:3546 [inline] [] blk_mq_alloc_map_and_rqs+0x1f4/0xe34 block/blk-mq.c:4114 [] __blk_mq_alloc_map_and_rqs block/blk-mq.c:4136 [inline] [] __blk_mq_alloc_map_and_rqs block/blk-mq.c:4127 [inline] [] blk_mq_realloc_tag_set_tags block/blk-mq.c:4803 [inline] [] __blk_mq_update_nr_hw_queues block/blk-mq.c:5134 [inline] [] blk_mq_update_nr_hw_queues+0xb14/0x1300 block/blk-mq.c:5186 [] nbd_start_device+0x170/0xba8 drivers/block/nbd.c:1489 [] nbd_start_device_ioctl drivers/block/nbd.c:1548 [inline] [] __nbd_ioctl drivers/block/nbd.c:1623 [inline] [] nbd_ioctl+0x474/0xbde drivers/block/nbd.c:1663 [] blkdev_ioctl+0xb2e/0x12da block/ioctl.c:791 [] vfs_ioctl fs/ioctl.c:51 [inline] [] __do_sys_ioctl fs/ioctl.c:597 [inline] [] __se_sys_ioctl fs/ioctl.c:583 [inline] [] __riscv_sys_ioctl+0x180/0x1e4 fs/ioctl.c:583 [] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 [] do_trap_ecall_u+0x3d8/0x56c arch/riscv/kernel/traps.c:343 [] handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:198 block nbd2: shutting down sockets