====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.8.5678/24657 is trying to acquire lock: ffff8880275446b8 (&q->elevator_lock){+.+.}-{4:4}, at: elevator_change+0x1bc/0x530 block/elevator.c:679 but task is already holding lock: ffff888027544190 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x15/0x20 block/blk-mq.c:206 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #6 (&q->q_usage_counter(io)#49){++++}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 blk_alloc_queue+0x610/0x790 block/blk-core.c:504 blk_mq_alloc_queue+0x174/0x290 block/blk-mq.c:4420 __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4467 nbd_dev_add+0x492/0xb10 drivers/block/nbd.c:1991 nbd_init+0x291/0x2b0 drivers/block/nbd.c:2729 do_one_initcall+0x11d/0x700 init/main.c:1347 do_initcall_level init/main.c:1409 [inline] do_initcalls init/main.c:1425 [inline] do_basic_setup init/main.c:1445 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1658 kernel_init+0x1f/0x1e0 init/main.c:1548 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #5 (fs_reclaim){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4329 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4343 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4565 [inline] slab_alloc_node mm/slub.c:4925 [inline] __kmalloc_cache_node_noprof+0x66/0x6c0 mm/slub.c:5530 _kmalloc_node_noprof include/linux/slab.h:1174 [inline] alloc_worker kernel/workqueue.c:2706 [inline] create_worker+0x110/0x750 kernel/workqueue.c:2849 workqueue_prepare_cpu+0xb5/0x160 kernel/workqueue.c:6841 cpuhp_invoke_callback+0x3b4/0x9a0 kernel/cpu.c:194 __cpuhp_invoke_callback_range+0x158/0x1d0 kernel/cpu.c:972 cpuhp_invoke_callback_range kernel/cpu.c:996 [inline] cpuhp_up_callbacks kernel/cpu.c:1027 [inline] _cpu_up+0x3f6/0x960 kernel/cpu.c:1674 cpu_up+0x1ba/0x230 kernel/cpu.c:1706 cpuhp_bringup_mask+0xf8/0x180 kernel/cpu.c:1772 cpuhp_bringup_cpus_parallel kernel/cpu.c:1862 [inline] bringup_nonboot_cpus+0x170/0x1b0 kernel/cpu.c:1876 smp_init+0x32/0x150 kernel/smp.c:1014 kernel_init_freeable+0x44b/0x7b0 init/main.c:1650 kernel_init+0x1f/0x1e0 init/main.c:1548 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #4 (cpu_hotplug_lock){++++}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read include/linux/percpu-rwsem.h:77 [inline] cpus_read_lock+0x42/0x170 kernel/cpu.c:490 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:190 nbd_reconnect_socket drivers/block/nbd.c:1379 [inline] nbd_genl_reconfigure+0xd82/0x1a00 drivers/block/nbd.c:2468 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2556 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900 sock_sendmsg_nosec net/socket.c:775 [inline] __sock_sendmsg net/socket.c:790 [inline] ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2684 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2738 __sys_sendmsg+0x160/0x210 net/socket.c:2770 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&nsock->tx_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 nbd_handle_cmd drivers/block/nbd.c:1143 [inline] nbd_queue_rq+0x428/0x1080 drivers/block/nbd.c:1207 blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2117 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2355 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2918 blk_mq_flush_plug_list block/blk-mq.c:2966 [inline] blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2938 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1273 blk_finish_plug block/blk-core.c:1300 [inline] __submit_bio+0x584/0x6c0 block/blk-core.c:690 __submit_bio_noacct_mq block/blk-core.c:763 [inline] submit_bio_noacct_nocheck+0x549/0xc00 block/blk-core.c:797 submit_bio_noacct+0xd17/0x1ff0 block/blk-core.c:928 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline] __bh_submit+0x658/0x850 fs/buffer.c:1225 bh_submit fs/buffer.c:1239 [inline] block_read_full_folio+0x1f7/0x8c0 fs/buffer.c:2449 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2510 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4140 read_mapping_folio include/linux/pagemap.h:1015 [inline] read_part_sector+0xd1/0x370 block/partitions/core.c:724 adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:357 check_partition block/partitions/core.c:143 [inline] blk_add_partitions block/partitions/core.c:591 [inline] bdev_disk_changed+0x7b1/0x1260 block/partitions/core.c:695 blkdev_get_whole+0x187/0x290 block/bdev.c:751 bdev_open+0x2c7/0xe40 block/bdev.c:960 blkdev_open+0x34e/0x4f0 block/fops.c:672 do_dentry_open+0x6ab/0x14d0 fs/open.c:947 vfs_open+0x82/0x3f0 fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x2873/0x4280 fs/namei.c:4859 do_file_open+0x20e/0x430 fs/namei.c:4888 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&cmd->lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199 blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2117 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2355 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2918 blk_mq_flush_plug_list block/blk-mq.c:2966 [inline] blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2938 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1273 blk_finish_plug block/blk-core.c:1300 [inline] __submit_bio+0x584/0x6c0 block/blk-core.c:690 __submit_bio_noacct_mq block/blk-core.c:763 [inline] submit_bio_noacct_nocheck+0x549/0xc00 block/blk-core.c:797 submit_bio_noacct+0xd17/0x1ff0 block/blk-core.c:928 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline] __bh_submit+0x658/0x850 fs/buffer.c:1225 bh_submit fs/buffer.c:1239 [inline] block_read_full_folio+0x1f7/0x8c0 fs/buffer.c:2449 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2510 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4140 read_mapping_folio include/linux/pagemap.h:1015 [inline] read_part_sector+0xd1/0x370 block/partitions/core.c:724 adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:357 check_partition block/partitions/core.c:143 [inline] blk_add_partitions block/partitions/core.c:591 [inline] bdev_disk_changed+0x7b1/0x1260 block/partitions/core.c:695 blkdev_get_whole+0x187/0x290 block/bdev.c:751 bdev_open+0x2c7/0xe40 block/bdev.c:960 blkdev_open+0x34e/0x4f0 block/fops.c:672 do_dentry_open+0x6ab/0x14d0 fs/open.c:947 vfs_open+0x82/0x3f0 fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x2873/0x4280 fs/namei.c:4859 do_file_open+0x20e/0x430 fs/namei.c:4888 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (set->srcu){.+.+}-{0:0}: lock_sync kernel/locking/lockdep.c:5916 [inline] lock_sync+0x9d/0x110 kernel/locking/lockdep.c:5904 srcu_lock_sync include/linux/srcu.h:199 [inline] __synchronize_srcu+0xa2/0x300 kernel/rcu/srcutree.c:1481 blk_mq_wait_quiesce_done block/blk-mq.c:284 [inline] blk_mq_wait_quiesce_done block/blk-mq.c:281 [inline] blk_mq_quiesce_queue block/blk-mq.c:304 [inline] blk_mq_quiesce_queue+0x149/0x1c0 block/blk-mq.c:299 elevator_switch+0x17b/0x7e0 block/elevator.c:576 elevator_change+0x352/0x530 block/elevator.c:681 elevator_set_default+0x29e/0x360 block/elevator.c:754 blk_register_queue+0x48e/0x630 block/blk-sysfs.c:992 __add_disk+0x73f/0xe40 block/genhd.c:528 add_disk_fwnode+0x118/0x5c0 block/genhd.c:597 add_disk include/linux/blkdev.h:800 [inline] nbd_dev_add+0x77a/0xb10 drivers/block/nbd.c:2021 nbd_init+0x291/0x2b0 drivers/block/nbd.c:2729 do_one_initcall+0x11d/0x700 init/main.c:1347 do_initcall_level init/main.c:1409 [inline] do_initcalls init/main.c:1425 [inline] do_basic_setup init/main.c:1445 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1658 kernel_init+0x1f/0x1e0 init/main.c:1548 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (&q->elevator_lock){+.+.}-{4:4}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 elevator_change+0x1bc/0x530 block/elevator.c:679 elevator_set_none+0x92/0xf0 block/elevator.c:769 blk_mq_elv_switch_none block/blk-mq.c:5101 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5146 [inline] blk_mq_update_nr_hw_queues+0x4c1/0x15f0 block/blk-mq.c:5211 nbd_start_device+0x1a6/0xbd0 drivers/block/nbd.c:1526 nbd_genl_connect+0xff2/0x1a40 drivers/block/nbd.c:2276 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2556 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900 sock_sendmsg_nosec net/socket.c:775 [inline] __sock_sendmsg net/socket.c:790 [inline] ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2684 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2738 __sys_sendmsg+0x160/0x210 net/socket.c:2770 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &q->elevator_lock --> fs_reclaim --> &q->q_usage_counter(io)#49 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#49); lock(fs_reclaim); lock(&q->q_usage_counter(io)#49); lock(&q->elevator_lock); *** DEADLOCK *** 6 locks held by syz.8.5678/24657: #0: ffffffff906ed6e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff906ed7a0 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline] #1: ffffffff906ed7a0 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline] #1: ffffffff906ed7a0 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:57 [inline] #1: ffffffff906ed7a0 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x57b/0x800 net/netlink/genetlink.c:1208 #2: ffff88802750c1c0 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x9d/0x15f0 block/blk-mq.c:5209 #3: ffff88802750c0d0 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0xb0/0x15f0 block/blk-mq.c:5210 #4: ffff888027544190 (&q->q_usage_counter(io)#49){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x15/0x20 block/blk-mq.c:206 #5: ffff8880275441c8 (&q->q_usage_counter(queue)#33){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x15/0x20 block/blk-mq.c:206 stack backtrace: CPU: 0 UID: 0 PID: 24657 Comm: syz.8.5678 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 elevator_change+0x1bc/0x530 block/elevator.c:679 elevator_set_none+0x92/0xf0 block/elevator.c:769 blk_mq_elv_switch_none block/blk-mq.c:5101 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5146 [inline] blk_mq_update_nr_hw_queues+0x4c1/0x15f0 block/blk-mq.c:5211 nbd_start_device+0x1a6/0xbd0 drivers/block/nbd.c:1526 nbd_genl_connect+0xff2/0x1a40 drivers/block/nbd.c:2276 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2556 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900 sock_sendmsg_nosec net/socket.c:775 [inline] __sock_sendmsg net/socket.c:790 [inline] ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2684 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2738 __sys_sendmsg+0x160/0x210 net/socket.c:2770 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fab02b9ce59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fab039ca028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fab02e15fa0 RCX: 00007fab02b9ce59 RDX: 0000000000000004 RSI: 0000200000001ac0 RDI: 0000000000000007 RBP: 00007fab02c32e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fab02e16038 R14: 00007fab02e15fa0 R15: 00007fff6d2b8768