====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.5.208/6347 is trying to acquire lock: ffffffff8875dea8 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0xd68/0x1d5c mm/percpu.c:1782 but task is already holding lock: ffffaf801a61bb58 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:205 [inline] ffffaf801a61bb58 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x868/0x10e4 block/blk-mq.c:5079 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+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:4399 __blk_mq_alloc_disk+0x2a/0x11a block/blk-mq.c:4446 nbd_dev_add+0x45c/0xb2e drivers/block/nbd.c:1951 nbd_init+0x3f4/0x41a drivers/block/nbd.c:2688 do_one_initcall+0x1a2/0xaec init/main.c:1283 do_initcall_level init/main.c:1345 [inline] do_initcalls init/main.c:1361 [inline] do_basic_setup init/main.c:1380 [inline] kernel_init_freeable+0x6e4/0x7a6 init/main.c:1593 kernel_init+0x28/0x24c init/main.c:1483 ret_from_fork_kernel+0x2a/0xbc6 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:4269 [inline] fs_reclaim_acquire+0xd0/0x106 mm/page_alloc.c:4283 might_alloc include/linux/sched/mm.h:318 [inline] prepare_alloc_pages+0x15a/0x532 mm/page_alloc.c:4951 __alloc_frozen_pages_noprof+0x164/0x2124 mm/page_alloc.c:5172 __alloc_pages_noprof+0xe/0x22 mm/page_alloc.c:5217 __alloc_pages_node_noprof include/linux/gfp.h:284 [inline] alloc_pages_node_noprof include/linux/gfp.h:311 [inline] pcpu_alloc_pages mm/percpu-vm.c:95 [inline] pcpu_populate_chunk+0x272/0xf48 mm/percpu-vm.c:285 pcpu_alloc_noprof+0x93e/0x1d5c mm/percpu.c:1870 bpf_map_alloc_percpu+0x23a/0x99e kernel/bpf/syscall.c:560 prealloc_init kernel/bpf/hashtab.c:344 [inline] htab_map_alloc+0x11c8/0x16ee kernel/bpf/hashtab.c:569 map_create+0x54c/0x27bc kernel/bpf/syscall.c:1497 __sys_bpf+0x39e/0x45ee kernel/bpf/syscall.c:6116 __do_sys_bpf kernel/bpf/syscall.c:6244 [inline] __se_sys_bpf kernel/bpf/syscall.c:6242 [inline] __riscv_sys_bpf+0x70/0xce kernel/bpf/syscall.c:6242 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x39e/0x53a 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:598 [inline] __mutex_lock+0x16a/0x19b4 kernel/locking/mutex.c:760 _mutex_lock_killable+0x16/0x1e kernel/locking/mutex.c:828 pcpu_alloc_noprof+0xd68/0x1d5c 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:3534 [inline] blk_mq_alloc_map_and_rqs+0x1f4/0xe34 block/blk-mq.c:4097 __blk_mq_alloc_map_and_rqs block/blk-mq.c:4119 [inline] __blk_mq_alloc_map_and_rqs+0x11a/0x1c6 block/blk-mq.c:4110 blk_mq_realloc_tag_set_tags block/blk-mq.c:4758 [inline] __blk_mq_update_nr_hw_queues+0xa66/0x10e4 block/blk-mq.c:5081 blk_mq_update_nr_hw_queues+0x42/0x66 block/blk-mq.c:5133 nbd_start_device+0x170/0xba8 drivers/block/nbd.c:1486 nbd_genl_connect+0xc1a/0x1b86 drivers/block/nbd.c:2236 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+0x850/0xdc8 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0xcc/0x160 net/socket.c:742 ____sys_sendmsg+0x640/0x79e net/socket.c:2630 ___sys_sendmsg+0x144/0x1e6 net/socket.c:2684 __sys_sendmsg+0x188/0x246 net/socket.c:2716 __do_sys_sendmsg net/socket.c:2721 [inline] __se_sys_sendmsg net/socket.c:2719 [inline] __riscv_sys_sendmsg+0x70/0xa2 net/socket.c:2719 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x39e/0x53a 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)#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.5.208/6347: #0: ffffffff89b5fa30 (cb_lock){++++}-{4:4}, at: genl_rcv+0x28/0x4c net/netlink/genetlink.c:1218 #1: ffffffff89b5f968 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline] #1: ffffffff89b5f968 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline] #1: ffffffff89b5f968 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:57 [inline] #1: ffffffff89b5f968 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x532/0x78e net/netlink/genetlink.c:1209 #2: ffffaf801a71d9c8 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x2a/0x66 block/blk-mq.c:5131 #3: ffffaf801a71d8d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0x3a/0x66 block/blk-mq.c:5132 #4: ffffaf801a61bb58 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:205 [inline] #4: ffffaf801a61bb58 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x868/0x10e4 block/blk-mq.c:5079 #5: ffffaf801a61bb90 (&q->q_usage_counter(queue)#3){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:205 [inline] #5: ffffaf801a61bb90 (&q->q_usage_counter(queue)#3){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues+0x868/0x10e4 block/blk-mq.c:5079 stack backtrace: CPU: 0 UID: 0 PID: 6347 Comm: syz.5.208 Not tainted syzkaller #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+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:598 [inline] [] __mutex_lock+0x16a/0x19b4 kernel/locking/mutex.c:760 [] _mutex_lock_killable+0x16/0x1e kernel/locking/mutex.c:828 [] pcpu_alloc_noprof+0xd68/0x1d5c 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:3534 [inline] [] blk_mq_alloc_map_and_rqs+0x1f4/0xe34 block/blk-mq.c:4097 [] __blk_mq_alloc_map_and_rqs block/blk-mq.c:4119 [inline] [] __blk_mq_alloc_map_and_rqs+0x11a/0x1c6 block/blk-mq.c:4110 [] blk_mq_realloc_tag_set_tags block/blk-mq.c:4758 [inline] [] __blk_mq_update_nr_hw_queues+0xa66/0x10e4 block/blk-mq.c:5081 [] blk_mq_update_nr_hw_queues+0x42/0x66 block/blk-mq.c:5133 [] nbd_start_device+0x170/0xba8 drivers/block/nbd.c:1486 [] nbd_genl_connect+0xc1a/0x1b86 drivers/block/nbd.c:2236 [] 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+0x850/0xdc8 net/netlink/af_netlink.c:1896 [] sock_sendmsg_nosec net/socket.c:727 [inline] [] __sock_sendmsg+0xcc/0x160 net/socket.c:742 [] ____sys_sendmsg+0x640/0x79e net/socket.c:2630 [] ___sys_sendmsg+0x144/0x1e6 net/socket.c:2684 [] __sys_sendmsg+0x188/0x246 net/socket.c:2716 [] __do_sys_sendmsg net/socket.c:2721 [inline] [] __se_sys_sendmsg net/socket.c:2719 [inline] [] __riscv_sys_sendmsg+0x70/0xa2 net/socket.c:2719 [] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 [] do_trap_ecall_u+0x39e/0x53a arch/riscv/kernel/traps.c:343 [] handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:198 nbd0: detected capacity change from 0 to 127