====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.299/5727 is trying to acquire lock: ffffffff88780f08 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0x20a/0x2204 mm/percpu.c:1782 but task is already holding lock: ffffaf801aa9d5e0 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] ffffaf801aa9d5e0 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5131 [inline] ffffaf801aa9d5e0 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x7c0/0x11e4 block/blk-mq.c:5185 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+0x1d2/0x44c kernel/locking/lockdep.c:5825 blk_alloc_queue+0x5b4/0x6c0 block/blk-core.c:461 blk_mq_alloc_queue+0x15e/0x250 block/blk-mq.c:4415 __blk_mq_alloc_disk+0x2a/0xd8 block/blk-mq.c:4462 nbd_dev_add+0x426/0xaec drivers/block/nbd.c:1954 nbd_init+0x3d4/0x3f8 drivers/block/nbd.c:2692 do_one_initcall+0x194/0xaa0 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+0x6ca/0x78c init/main.c:1688 kernel_init+0x28/0x240 init/main.c:1578 ret_from_fork_kernel+0x2a/0xbbc arch/riscv/kernel/process.c:228 ret_from_fork_kernel_asm+0x16/0x18 arch/riscv/kernel/entry.S:363 -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1d2/0x44c kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4331 [inline] fs_reclaim_acquire+0xc6/0x100 mm/page_alloc.c:4345 might_alloc include/linux/sched/mm.h:317 [inline] prepare_alloc_pages+0x146/0x51c mm/page_alloc.c:5008 __alloc_frozen_pages_noprof+0x158/0x20c8 mm/page_alloc.c:5229 __alloc_pages_noprof+0xe/0x138 mm/page_alloc.c:5274 __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+0x16c/0xd00 mm/percpu-vm.c:285 pcpu_alloc_noprof+0x50e/0x2204 mm/percpu.c:1870 xt_percpu_counter_alloc+0x138/0x194 net/netfilter/x_tables.c:1934 find_check_entry.isra.0+0xe8/0x880 net/ipv6/netfilter/ip6_tables.c:545 translate_table+0xb0c/0x142c net/ipv6/netfilter/ip6_tables.c:733 ip6t_register_table+0x11a/0x3f8 net/ipv6/netfilter/ip6_tables.c:1751 ip6table_security_table_init+0x46/0x70 net/ipv6/netfilter/ip6table_security.c:45 xt_find_table_lock+0x294/0x4c0 net/netfilter/x_tables.c:1260 xt_request_find_table_lock+0x28/0xfc net/netfilter/x_tables.c:1285 get_info+0x164/0x52c net/ipv6/netfilter/ip6_tables.c:979 do_ip6t_get_ctl+0x16a/0x900 net/ipv6/netfilter/ip6_tables.c:1668 nf_getsockopt+0x6e/0xd4 net/netfilter/nf_sockopt.c:116 ipv6_getsockopt+0x412/0x954 net/ipv6/ipv6_sockglue.c:1473 tcp_getsockopt+0x84/0xd8 net/ipv4/tcp.c:4832 sock_common_getsockopt+0x86/0xb8 net/core/sock.c:3946 do_sock_getsockopt+0x34e/0x5d4 net/socket.c:2383 __sys_getsockopt+0xd6/0x170 net/socket.c:2412 __do_sys_getsockopt net/socket.c:2419 [inline] __se_sys_getsockopt net/socket.c:2416 [inline] __riscv_sys_getsockopt+0xa6/0x114 net/socket.c:2416 syscall_handler+0x92/0x114 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x3d2/0x58c arch/riscv/kernel/traps.c:344 handle_exception+0x15e/0x16a arch/riscv/kernel/entry.S:232 -> #0 (pcpu_alloc_mutex){+.+.}-{4:4}: check_noncircular+0x138/0x14c 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+0xe9c/0x25ac kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1d2/0x44c kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x164/0x1890 kernel/locking/mutex.c:776 _mutex_lock_killable+0x16/0x20 kernel/locking/mutex.c:844 pcpu_alloc_noprof+0x20a/0x2204 mm/percpu.c:1782 init_alloc_hint lib/sbitmap.c:16 [inline] sbitmap_init_node+0x298/0x748 lib/sbitmap.c:126 sbitmap_queue_init_node+0x3a/0x3fc lib/sbitmap.c:454 bt_alloc block/blk-mq-tag.c:546 [inline] blk_mq_init_tags+0x15a/0x2d8 block/blk-mq-tag.c:571 blk_mq_alloc_rq_map block/blk-mq.c:3546 [inline] blk_mq_alloc_map_and_rqs+0x1d2/0xda8 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:4802 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5133 [inline] blk_mq_update_nr_hw_queues+0xa4a/0x11e4 block/blk-mq.c:5185 nbd_start_device+0x156/0xb74 drivers/block/nbd.c:1489 nbd_genl_connect+0xe74/0x1a4c drivers/block/nbd.c:2239 genl_family_rcv_msg_doit+0x1f6/0x2d8 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x4b2/0x73c net/netlink/genetlink.c:1210 netlink_rcv_skb+0x1e8/0x394 net/netlink/af_netlink.c:2550 genl_rcv+0x32/0x4c net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x50c/0x7d8 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x7e0/0xd64 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0xca/0x160 net/socket.c:742 ____sys_sendmsg+0x636/0x794 net/socket.c:2592 ___sys_sendmsg+0x1a4/0x1e8 net/socket.c:2646 __sys_sendmsg+0x18e/0x234 net/socket.c:2678 __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __riscv_sys_sendmsg+0x70/0xa4 net/socket.c:2681 syscall_handler+0x92/0x114 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x3d2/0x58c arch/riscv/kernel/traps.c:344 handle_exception+0x15e/0x16a arch/riscv/kernel/entry.S:232 other info that might help us debug this: Chain exists of: pcpu_alloc_mutex --> 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(pcpu_alloc_mutex); *** DEADLOCK *** 6 locks held by syz.2.299/5727: #0: ffffffff89c01ed0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x24/0x4c net/netlink/genetlink.c:1218 #1: ffffffff89c01dc8 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline] #1: ffffffff89c01dc8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline] #1: ffffffff89c01dc8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:57 [inline] #1: ffffffff89c01dc8 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x4d2/0x73c net/netlink/genetlink.c:1209 #2: ffffaf801a7e29d0 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x9e/0x11e4 block/blk-mq.c:5183 #3: ffffaf801a7e28d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0xb2/0x11e4 block/blk-mq.c:5184 #4: ffffaf801aa9d5e0 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #4: ffffaf801aa9d5e0 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5131 [inline] #4: ffffaf801aa9d5e0 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x7c0/0x11e4 block/blk-mq.c:5185 #5: ffffaf801aa9d618 (&q->q_usage_counter(queue)#3){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:206 [inline] #5: ffffaf801aa9d618 (&q->q_usage_counter(queue)#3){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5131 [inline] #5: ffffaf801aa9d618 (&q->q_usage_counter(queue)#3){+.+.}-{0:0}, at: blk_mq_update_nr_hw_queues+0x7c0/0x11e4 block/blk-mq.c:5185 stack backtrace: CPU: 1 UID: 0 PID: 5727 Comm: syz.2.299 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+0x114/0x1ac lib/dump_stack.c:120 [] dump_stack+0x1c/0x28 lib/dump_stack.c:129 [] print_circular_bug+0x250/0x29c kernel/locking/lockdep.c:2043 [] check_noncircular+0x138/0x14c 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+0xe9c/0x25ac kernel/locking/lockdep.c:5237 [] lock_acquire kernel/locking/lockdep.c:5868 [inline] [] lock_acquire+0x1d2/0x44c kernel/locking/lockdep.c:5825 [] __mutex_lock_common kernel/locking/mutex.c:614 [inline] [] __mutex_lock+0x164/0x1890 kernel/locking/mutex.c:776 [] _mutex_lock_killable+0x16/0x20 kernel/locking/mutex.c:844 [] pcpu_alloc_noprof+0x20a/0x2204 mm/percpu.c:1782 [] init_alloc_hint lib/sbitmap.c:16 [inline] [] sbitmap_init_node+0x298/0x748 lib/sbitmap.c:126 [] sbitmap_queue_init_node+0x3a/0x3fc lib/sbitmap.c:454 [] bt_alloc block/blk-mq-tag.c:546 [inline] [] blk_mq_init_tags+0x15a/0x2d8 block/blk-mq-tag.c:571 [] blk_mq_alloc_rq_map block/blk-mq.c:3546 [inline] [] blk_mq_alloc_map_and_rqs+0x1d2/0xda8 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:4802 [inline] [] __blk_mq_update_nr_hw_queues block/blk-mq.c:5133 [inline] [] blk_mq_update_nr_hw_queues+0xa4a/0x11e4 block/blk-mq.c:5185 [] nbd_start_device+0x156/0xb74 drivers/block/nbd.c:1489 [] nbd_genl_connect+0xe74/0x1a4c drivers/block/nbd.c:2239 [] genl_family_rcv_msg_doit+0x1f6/0x2d8 net/netlink/genetlink.c:1115 [] genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] [] genl_rcv_msg+0x4b2/0x73c net/netlink/genetlink.c:1210 [] netlink_rcv_skb+0x1e8/0x394 net/netlink/af_netlink.c:2550 [] genl_rcv+0x32/0x4c net/netlink/genetlink.c:1219 [] netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] [] netlink_unicast+0x50c/0x7d8 net/netlink/af_netlink.c:1344 [] netlink_sendmsg+0x7e0/0xd64 net/netlink/af_netlink.c:1894 [] sock_sendmsg_nosec net/socket.c:727 [inline] [] __sock_sendmsg+0xca/0x160 net/socket.c:742 [] ____sys_sendmsg+0x636/0x794 net/socket.c:2592 [] ___sys_sendmsg+0x1a4/0x1e8 net/socket.c:2646 [] __sys_sendmsg+0x18e/0x234 net/socket.c:2678 [] __do_sys_sendmsg net/socket.c:2683 [inline] [] __se_sys_sendmsg net/socket.c:2681 [inline] [] __riscv_sys_sendmsg+0x70/0xa4 net/socket.c:2681 [] syscall_handler+0x92/0x114 arch/riscv/include/asm/syscall.h:112 [] do_trap_ecall_u+0x3d2/0x58c arch/riscv/kernel/traps.c:344 [] handle_exception+0x15e/0x16a arch/riscv/kernel/entry.S:232 nbd0: detected capacity change from 0 to 63