======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.6.1879/11430 is trying to acquire lock:
ffff0000c827c678 (&q->elevator_lock){+.+.}-{4:4}, at: elevator_change+0x188/0x35c block/elevator.c:679

but task is already holding lock:
ffff0000c827c158 (&q->q_usage_counter(io)#38){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x20/0x38 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)#38){++++}-{0:0}:
       blk_alloc_queue+0x488/0x590 block/blk-core.c:461
       blk_mq_alloc_queue+0x148/0x284 block/blk-mq.c:4453
       __blk_mq_alloc_disk+0x38/0x10c block/blk-mq.c:4500
       nbd_dev_add+0x3d0/0x880 drivers/block/nbd.c:1954
       nbd_init+0x15c/0x174 drivers/block/nbd.c:2692
       do_one_initcall+0x274/0xc38 init/main.c:1392
       do_initcall_level+0x12c/0x1c4 init/main.c:1454
       do_initcalls+0x70/0xd0 init/main.c:1470
       do_basic_setup+0x7c/0x90 init/main.c:1490
       kernel_init_freeable+0x268/0x3a8 init/main.c:1703
       kernel_init+0x24/0x1dc init/main.c:1593
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842

-> #5 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:4320 [inline]
       fs_reclaim_acquire+0x90/0x110 mm/page_alloc.c:4334
       might_alloc include/linux/sched/mm.h:317 [inline]
       slab_pre_alloc_hook mm/slub.c:4521 [inline]
       slab_alloc_node mm/slub.c:4876 [inline]
       kmem_cache_alloc_node_noprof+0x60/0x6c8 mm/slub.c:4951
       kmalloc_reserve+0xc4/0x214 net/core/skbuff.c:613
       __alloc_skb+0x230/0x610 net/core/skbuff.c:713
       alloc_skb include/linux/skbuff.h:1385 [inline]
       __ip6_append_data+0x289c/0x383c net/ipv6/ip6_output.c:1701
       ip6_append_data+0x100/0x270 net/ipv6/ip6_output.c:1891
       rawv6_sendmsg+0xe3c/0x1438 net/ipv6/raw.c:913
       inet_sendmsg+0xb4/0xd8 net/ipv4/af_inet.c:866
       sock_sendmsg_nosec net/socket.c:787 [inline]
       __sock_sendmsg+0xc8/0x138 net/socket.c:802
       ____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2698
       ___sys_sendmsg+0x198/0x224 net/socket.c:2752
       __sys_sendmsg+0x160/0x214 net/socket.c:2784
       __do_sys_sendmsg net/socket.c:2789 [inline]
       __se_sys_sendmsg net/socket.c:2787 [inline]
       __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2787
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

-> #4 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_sock_nested+0x58/0x110 net/core/sock.c:3787
       lock_sock include/net/sock.h:1713 [inline]
       inet_shutdown+0x74/0x354 net/ipv4/af_inet.c:915
       kernel_sock_shutdown+0x6c/0x80 net/socket.c:3785
       nbd_mark_nsock_dead+0x280/0x4f4 drivers/block/nbd.c:318
       recv_work+0x1d58/0x1e74 drivers/block/nbd.c:1021
       process_one_work kernel/workqueue.c:3314 [inline]
       process_scheduled_works+0x788/0x10b8 kernel/workqueue.c:3397
       worker_thread+0x798/0xbd0 kernel/workqueue.c:3478
       kthread+0x304/0x3d4 kernel/kthread.c:436
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842

-> #3 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x164/0xed0 kernel/locking/mutex.c:820
       mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
       nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
       nbd_queue_rq+0x1f4/0xbd8 drivers/block/nbd.c:1207
       blk_mq_dispatch_rq_list+0x3d4/0x13a8 block/blk-mq.c:2148
       __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+0xa48/0x10e8 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xa8/0x158 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x300/0x4dc block/blk-mq.c:2387
       blk_mq_dispatch_list+0xa28/0xb2c block/blk-mq.c:-1
       blk_mq_flush_plug_list+0x3ac/0x494 block/blk-mq.c:2997
       __blk_flush_plug+0x364/0x440 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x3a0/0x480 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x288/0xaac block/blk-core.c:753
       submit_bio_noacct+0xd7c/0x17f0 block/blk-core.c:884
       submit_bio+0x38c/0x528 block/blk-core.c:926
       blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
       submit_bh_wbc+0x4c8/0x5ac fs/buffer.c:2737
       submit_bh fs/buffer.c:2742 [inline]
       block_read_full_folio+0x47c/0x754 fs/buffer.c:2344
       blkdev_read_folio+0x28/0x38 block/fops.c:494
       filemap_read_folio+0xf0/0x2fc mm/filemap.c:2502
       do_read_cache_folio+0x35c/0x5a8 mm/filemap.c:4107
       read_cache_folio+0x68/0x88 mm/filemap.c:4139
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xcc/0x708 block/partitions/core.c:724
       adfspart_check_ICS+0xa4/0x720 block/partitions/acorn.c:356
       check_partition block/partitions/core.c:143 [inline]
       blk_add_partitions block/partitions/core.c:591 [inline]
       bdev_disk_changed+0x6c4/0x11ec block/partitions/core.c:695
       blkdev_get_whole+0x15c/0x240 block/bdev.c:756
       bdev_open+0x2b4/0x880 block/bdev.c:965
       blkdev_open+0x2d4/0x408 block/fops.c:697
       do_dentry_open+0x5c4/0xfb8 fs/open.c:947
       vfs_open+0x44/0x2dc fs/open.c:1079
       do_open fs/namei.c:4699 [inline]
       path_openat+0x22d4/0x2b88 fs/namei.c:4858
       do_file_open+0x1c8/0x2e8 fs/namei.c:4887
       do_sys_openat2+0x114/0x1e8 fs/open.c:1364
       do_sys_open+0xac/0xdc fs/open.c:1370
       __do_sys_openat fs/open.c:1386 [inline]
       __se_sys_openat fs/open.c:1381 [inline]
       __arm64_sys_openat+0xa0/0xbc fs/open.c:1381
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

-> #2 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x164/0xed0 kernel/locking/mutex.c:820
       mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
       nbd_queue_rq+0xb0/0xbd8 drivers/block/nbd.c:1199
       blk_mq_dispatch_rq_list+0x3d4/0x13a8 block/blk-mq.c:2148
       __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+0xa48/0x10e8 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xa8/0x158 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x300/0x4dc block/blk-mq.c:2387
       blk_mq_dispatch_list+0xa28/0xb2c block/blk-mq.c:-1
       blk_mq_flush_plug_list+0x3ac/0x494 block/blk-mq.c:2997
       __blk_flush_plug+0x364/0x440 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x3a0/0x480 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x288/0xaac block/blk-core.c:753
       submit_bio_noacct+0xd7c/0x17f0 block/blk-core.c:884
       submit_bio+0x38c/0x528 block/blk-core.c:926
       blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
       submit_bh_wbc+0x4c8/0x5ac fs/buffer.c:2737
       submit_bh fs/buffer.c:2742 [inline]
       block_read_full_folio+0x47c/0x754 fs/buffer.c:2344
       blkdev_read_folio+0x28/0x38 block/fops.c:494
       filemap_read_folio+0xf0/0x2fc mm/filemap.c:2502
       do_read_cache_folio+0x35c/0x5a8 mm/filemap.c:4107
       read_cache_folio+0x68/0x88 mm/filemap.c:4139
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xcc/0x708 block/partitions/core.c:724
       adfspart_check_ICS+0xa4/0x720 block/partitions/acorn.c:356
       check_partition block/partitions/core.c:143 [inline]
       blk_add_partitions block/partitions/core.c:591 [inline]
       bdev_disk_changed+0x6c4/0x11ec block/partitions/core.c:695
       blkdev_get_whole+0x15c/0x240 block/bdev.c:756
       bdev_open+0x2b4/0x880 block/bdev.c:965
       blkdev_open+0x2d4/0x408 block/fops.c:697
       do_dentry_open+0x5c4/0xfb8 fs/open.c:947
       vfs_open+0x44/0x2dc fs/open.c:1079
       do_open fs/namei.c:4699 [inline]
       path_openat+0x22d4/0x2b88 fs/namei.c:4858
       do_file_open+0x1c8/0x2e8 fs/namei.c:4887
       do_sys_openat2+0x114/0x1e8 fs/open.c:1364
       do_sys_open+0xac/0xdc fs/open.c:1370
       __do_sys_openat fs/open.c:1386 [inline]
       __se_sys_openat fs/open.c:1381 [inline]
       __arm64_sys_openat+0xa0/0xbc fs/open.c:1381
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

-> #1 (set->srcu){.+.+}-{0:0}:
       srcu_lock_sync include/linux/srcu.h:199 [inline]
       __synchronize_srcu+0xc8/0x268 kernel/rcu/srcutree.c:1481
       synchronize_srcu+0x41c/0x5d4 kernel/rcu/srcutree.c:-1
       blk_mq_wait_quiesce_done+0x88/0xac block/blk-mq.c:284
       blk_mq_quiesce_queue+0x70/0x8c block/blk-mq.c:304
       elevator_switch+0x128/0x38c block/elevator.c:576
       elevator_change+0x204/0x35c block/elevator.c:681
       elevator_set_default+0x190/0x2b0 block/elevator.c:754
       blk_register_queue+0x2fc/0x3d4 block/blk-sysfs.c:987
       __add_disk+0x558/0xb44 block/genhd.c:528
       add_disk_fwnode+0xd4/0x404 block/genhd.c:597
       device_add_disk+0x38/0x4c block/genhd.c:627
       add_disk include/linux/blkdev.h:794 [inline]
       nbd_dev_add+0x598/0x880 drivers/block/nbd.c:1984
       nbd_init+0x15c/0x174 drivers/block/nbd.c:2692
       do_one_initcall+0x274/0xc38 init/main.c:1392
       do_initcall_level+0x12c/0x1c4 init/main.c:1454
       do_initcalls+0x70/0xd0 init/main.c:1470
       do_basic_setup+0x7c/0x90 init/main.c:1490
       kernel_init_freeable+0x268/0x3a8 init/main.c:1703
       kernel_init+0x24/0x1dc init/main.c:1593
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842

-> #0 (&q->elevator_lock){+.+.}-{4:4}:
       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+0x17c0/0x2ebc kernel/locking/lockdep.c:5237
       lock_acquire+0x140/0x364 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x164/0xed0 kernel/locking/mutex.c:820
       mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
       elevator_change+0x188/0x35c block/elevator.c:679
       elevator_set_none+0xa8/0x13c block/elevator.c:769
       blk_mq_elv_switch_none block/blk-mq.c:5134 [inline]
       __blk_mq_update_nr_hw_queues block/blk-mq.c:5179 [inline]
       blk_mq_update_nr_hw_queues+0x4c4/0x11e0 block/blk-mq.c:5244
       nbd_start_device+0x15c/0xa44 drivers/block/nbd.c:1489
       nbd_genl_connect+0xffc/0x15d4 drivers/block/nbd.c:2239
       genl_family_rcv_msg_doit+0x1e4/0x2d4 net/netlink/genetlink.c:1114
       genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
       genl_rcv_msg+0x43c/0x620 net/netlink/genetlink.c:1209
       netlink_rcv_skb+0x238/0x414 net/netlink/af_netlink.c:2555
       genl_rcv+0x38/0x50 net/netlink/genetlink.c:1218
       netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
       netlink_unicast+0x600/0x7f8 net/netlink/af_netlink.c:1344
       netlink_sendmsg+0x648/0x948 net/netlink/af_netlink.c:1899
       sock_sendmsg_nosec net/socket.c:787 [inline]
       __sock_sendmsg+0xc8/0x138 net/socket.c:802
       ____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2698
       ___sys_sendmsg+0x198/0x224 net/socket.c:2752
       __sys_sendmsg+0x160/0x214 net/socket.c:2784
       __do_sys_sendmsg net/socket.c:2789 [inline]
       __se_sys_sendmsg net/socket.c:2787 [inline]
       __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2787
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

other info that might help us debug this:

Chain exists of:
  &q->elevator_lock --> fs_reclaim --> &q->q_usage_counter(io)#38

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&q->q_usage_counter(io)#38);
                               lock(fs_reclaim);
                               lock(&q->q_usage_counter(io)#38);
  lock(&q->elevator_lock);

 *** DEADLOCK ***

6 locks held by syz.6.1879/11430:
 #0: ffff800089d30d48 (cb_lock){++++}-{4:4}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:1217
 #1: ffff800089d30b80 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
 #1: ffff800089d30b80 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
 #1: ffff800089d30b80 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0xec/0x620 net/netlink/genetlink.c:1208
 #2: ffff0000c817b1c0 (&set->update_nr_hwq_lock){++++}-{4:4}, at: blk_mq_update_nr_hw_queues+0x98/0x11e0 block/blk-mq.c:5242
 #3: ffff0000c817b0d0 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0xa4/0x11e0 block/blk-mq.c:5243
 #4: ffff0000c827c158 (&q->q_usage_counter(io)#38){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x20/0x38 block/blk-mq.c:206
 #5: ffff0000c827c190 (&q->q_usage_counter(queue)#22){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x20/0x38 block/blk-mq.c:206

stack backtrace:
CPU: 0 UID: 0 PID: 11430 Comm: syz.6.1879 Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_circular_bug+0x328/0x330 kernel/locking/lockdep.c:2043
 check_noncircular+0x158/0x174 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+0x17c0/0x2ebc kernel/locking/lockdep.c:5237
 lock_acquire+0x140/0x364 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x164/0xed0 kernel/locking/mutex.c:820
 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
 elevator_change+0x188/0x35c block/elevator.c:679
 elevator_set_none+0xa8/0x13c block/elevator.c:769
 blk_mq_elv_switch_none block/blk-mq.c:5134 [inline]
 __blk_mq_update_nr_hw_queues block/blk-mq.c:5179 [inline]
 blk_mq_update_nr_hw_queues+0x4c4/0x11e0 block/blk-mq.c:5244
 nbd_start_device+0x15c/0xa44 drivers/block/nbd.c:1489
 nbd_genl_connect+0xffc/0x15d4 drivers/block/nbd.c:2239
 genl_family_rcv_msg_doit+0x1e4/0x2d4 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x43c/0x620 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x238/0x414 net/netlink/af_netlink.c:2555
 genl_rcv+0x38/0x50 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x600/0x7f8 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x648/0x948 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg+0xc8/0x138 net/socket.c:802
 ____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2698
 ___sys_sendmsg+0x198/0x224 net/socket.c:2752
 __sys_sendmsg+0x160/0x214 net/socket.c:2784
 __do_sys_sendmsg net/socket.c:2789 [inline]
 __se_sys_sendmsg net/socket.c:2787 [inline]
 __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2787
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594