======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.3237/13392 is trying to acquire lock:
ffff8881099d7800 (&q->elevator_lock){+.+.}-{4:4}, at: elevator_change+0x1af/0x480

but task is already holding lock:
ffff8881099d72c0 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: elevator_change+0x194/0x480

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #6 (&q->q_usage_counter(io)#52){++++}-{0:0}:
       blk_alloc_queue+0x53e/0x630
       __blk_mq_alloc_disk+0x194/0x390
       nbd_dev_add+0x494/0xb60
       nbd_init+0x15f/0x1e0
       do_one_initcall+0x256/0x880
       do_initcall_level+0x10a/0x1a0
       do_initcalls+0x59/0xa0
       kernel_init_freeable+0x32f/0x4b0
       kernel_init+0x1d/0x1d0
       ret_from_fork+0x5b0/0xb20
       ret_from_fork_asm+0x1a/0x30

-> #5 (fs_reclaim){+.+.}-{0:0}:
       fs_reclaim_acquire+0x71/0x100
       kmem_cache_alloc_node_noprof+0x48/0x700
       __alloc_skb+0x262/0x440
       tcp_stream_alloc_skb+0x3d/0x350
       tcp_sendmsg_locked+0x10e1/0x51e0
       tcp_sendmsg+0x2f/0x50
       sock_write_iter+0x421/0x550
       vfs_write+0x612/0xba0
       ksys_write+0x150/0x270
       do_syscall_64+0xf0/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (sk_lock-AF_INET){+.+.}-{0:0}:
       lock_sock_nested+0x48/0x100
       inet_shutdown+0x6a/0x390
       nbd_mark_nsock_dead+0x2cb/0x550
       recv_work+0x1cb5/0x1dd0
       process_scheduled_works+0xa2f/0x1470
       worker_thread+0xe79/0x1460
       kthread+0x787/0x910
       ret_from_fork+0x5b0/0xb20
       ret_from_fork_asm+0x1a/0x30

-> #3 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock+0x199/0x12d0
       nbd_queue_rq+0x373/0x1150
       blk_mq_dispatch_rq_list+0x499/0x1990
       __blk_mq_sched_dispatch_requests+0xd38/0x1570
       blk_mq_sched_dispatch_requests+0xd7/0x190
       blk_mq_run_hw_queue+0x348/0x4f0
       blk_mq_dispatch_list+0xd11/0xe10
       blk_mq_flush_plug_list+0x45f/0x540
       __blk_flush_plug+0x3ed/0x4d0
       __submit_bio+0x4c6/0x5d0
       submit_bio_noacct_nocheck+0x2f4/0xa20
       block_read_full_folio+0x599/0x830
       filemap_read_folio+0x12c/0x3a0
       do_read_cache_folio+0x354/0x590
       read_part_sector+0xb6/0x2b0
       adfspart_check_ICS+0xa5/0xa40
       bdev_disk_changed+0x785/0x14c0
       blkdev_get_whole+0x372/0x510
       bdev_open+0x324/0xd70
       blkdev_open+0x461/0x600
       do_dentry_open+0x7a4/0x1230
       vfs_open+0x3b/0x340
       path_openat+0x3642/0x4050
       do_filp_open+0x23f/0x4a0
       do_sys_openat2+0x12f/0x220
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0xf0/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock+0x199/0x12d0
       nbd_queue_rq+0xc1/0x1150
       blk_mq_dispatch_rq_list+0x499/0x1990
       __blk_mq_sched_dispatch_requests+0xd38/0x1570
       blk_mq_sched_dispatch_requests+0xd7/0x190
       blk_mq_run_hw_queue+0x348/0x4f0
       blk_mq_dispatch_list+0xd11/0xe10
       blk_mq_flush_plug_list+0x45f/0x540
       __blk_flush_plug+0x3ed/0x4d0
       __submit_bio+0x4c6/0x5d0
       submit_bio_noacct_nocheck+0x2f4/0xa20
       block_read_full_folio+0x599/0x830
       filemap_read_folio+0x12c/0x3a0
       do_read_cache_folio+0x354/0x590
       read_part_sector+0xb6/0x2b0
       adfspart_check_ICS+0xa5/0xa40
       bdev_disk_changed+0x785/0x14c0
       blkdev_get_whole+0x372/0x510
       bdev_open+0x324/0xd70
       blkdev_open+0x461/0x600
       do_dentry_open+0x7a4/0x1230
       vfs_open+0x3b/0x340
       path_openat+0x3642/0x4050
       do_filp_open+0x23f/0x4a0
       do_sys_openat2+0x12f/0x220
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0xf0/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (set->srcu){.+.+}-{0:0}:
       __synchronize_srcu+0xc9/0x3d0
       elevator_switch+0x1e8/0x750
       elevator_change+0x2fa/0x480
       elevator_set_default+0x375/0x440
       blk_register_queue+0x308/0x3a0
       __add_disk+0x6cb/0xe30
       add_disk_fwnode+0xfb/0x4b0
       nbd_dev_add+0x733/0xb60
       nbd_init+0x15f/0x1e0
       do_one_initcall+0x256/0x880
       do_initcall_level+0x10a/0x1a0
       do_initcalls+0x59/0xa0
       kernel_init_freeable+0x32f/0x4b0
       kernel_init+0x1d/0x1d0
       ret_from_fork+0x5b0/0xb20
       ret_from_fork_asm+0x1a/0x30

-> #0 (&q->elevator_lock){+.+.}-{4:4}:
       __lock_acquire+0x1520/0x2cd0
       lock_acquire+0x116/0x340
       __mutex_lock+0x199/0x12d0
       elevator_change+0x1af/0x480
       elevator_set_none+0xb5/0x140
       blk_mq_update_nr_hw_queues+0x5ec/0x1a70
       nbd_start_device+0x189/0xb30
       nbd_genl_connect+0x1597/0x1c10
       genl_family_rcv_msg_doit+0x233/0x340
       genl_rcv_msg+0x614/0x7a0
       netlink_rcv_skb+0x226/0x4a0
       genl_rcv+0x28/0x40
       netlink_unicast+0x833/0x9f0
       netlink_sendmsg+0x813/0xb40
       ____sys_sendmsg+0xa67/0xad0
       ___sys_sendmsg+0x2a5/0x360
       __x64_sys_sendmsg+0x1bd/0x2a0
       do_syscall_64+0xf0/0xf80
       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)#52

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&q->q_usage_counter(io)#52);
                               lock(fs_reclaim);
                               lock(&q->q_usage_counter(io)#52);
  lock(&q->elevator_lock);

 *** DEADLOCK ***

6 locks held by syz.2.3237/13392:
 #0: ffffffff8f7b3810 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f7b3628 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
 #2: ffff888109bc49d0 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0xab/0x1a70
 #3: ffff888109bc48d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0xbe/0x1a70
 #4: ffff8881099d72c0 (&q->q_usage_counter(io)#52){++++}-{0:0}, at: elevator_change+0x194/0x480
 #5: ffff8881099d72f8 (&q->q_usage_counter(queue)#36){+.+.}-{0:0}, at: elevator_change+0x194/0x480

stack backtrace:
CPU: 1 UID: 0 PID: 13392 Comm: syz.2.3237 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x1a9/0x280
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x1520/0x2cd0
 lock_acquire+0x116/0x340
 __mutex_lock+0x199/0x12d0
 elevator_change+0x1af/0x480
 elevator_set_none+0xb5/0x140
 blk_mq_update_nr_hw_queues+0x5ec/0x1a70
 nbd_start_device+0x189/0xb30
 nbd_genl_connect+0x1597/0x1c10
 genl_family_rcv_msg_doit+0x233/0x340
 genl_rcv_msg+0x614/0x7a0
 netlink_rcv_skb+0x226/0x4a0
 genl_rcv+0x28/0x40
 netlink_unicast+0x833/0x9f0
 netlink_sendmsg+0x813/0xb40
 ____sys_sendmsg+0xa67/0xad0
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1bd/0x2a0
 do_syscall_64+0xf0/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2a2659ce59
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:00007f2a273ff028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f2a26815fa0 RCX: 00007f2a2659ce59
RDX: 000000000400400c RSI: 0000200000001ac0 RDI: 0000000000000006
RBP: 00007f2a26632e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2a26816038 R14: 00007f2a26815fa0 R15: 00007ffedf26b118
 </TASK>
