syzbot

======================================================
WARNING: possible circular locking dependency detected
6.14.0-syzkaller-03576-g1e1ba8d23dae #0 Not tainted
------------------------------------------------------
syz.5.667/9051 is trying to acquire lock:
ffff888025989f10 (set->srcu){.+.+}-{0:0}, at: srcu_lock_sync include/linux/srcu.h:173 [inline]
ffff888025989f10 (set->srcu){.+.+}-{0:0}, at: __synchronize_srcu+0x1c/0x290 kernel/rcu/srcutree.c:1427

but task is already holding lock:
ffff888025df05d8 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_mq_elv_switch_none block/blk-mq.c:4937 [inline]
ffff888025df05d8 (&q->sysfs_lock){+.+.}-{4:4}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5018 [inline]
ffff888025df05d8 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0x4a9/0x1360 block/blk-mq.c:5070

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (&q->sysfs_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:587 [inline]
       __mutex_lock+0x19a/0xb00 kernel/locking/mutex.c:732
       blk_mq_elv_switch_none block/blk-mq.c:4937 [inline]
       __blk_mq_update_nr_hw_queues block/blk-mq.c:5018 [inline]
       blk_mq_update_nr_hw_queues+0x4a9/0x1360 block/blk-mq.c:5070
       nbd_start_device+0x172/0xcd0 drivers/block/nbd.c:1476
       nbd_start_device_ioctl drivers/block/nbd.c:1527 [inline]
       __nbd_ioctl drivers/block/nbd.c:1602 [inline]
       nbd_ioctl+0x219/0xda0 drivers/block/nbd.c:1642
       blkdev_ioctl+0x277/0x6d0 block/ioctl.c:693
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (&q->q_usage_counter(io)#54){++++}-{0:0}:
       bio_queue_enter block/blk.h:78 [inline]
       blk_mq_submit_bio+0x20e9/0x2600 block/blk-mq.c:3091
       __submit_bio+0x3cf/0x690 block/blk-core.c:628
       __submit_bio_noacct_mq block/blk-core.c:715 [inline]
       submit_bio_noacct_nocheck+0x663/0xd30 block/blk-core.c:744
       submit_bio_noacct+0x50d/0x1ec0 block/blk-core.c:867
       submit_bh fs/buffer.c:2807 [inline]
       block_read_full_folio+0x34e/0x850 fs/buffer.c:2418
       filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2400
       filemap_update_page mm/filemap.c:2484 [inline]
       filemap_get_pages+0x10a8/0x1c20 mm/filemap.c:2612
       filemap_read+0x3d2/0xe90 mm/filemap.c:2701
       blkdev_read_iter+0x190/0x4d0 block/fops.c:796
       new_sync_read fs/read_write.c:489 [inline]
       vfs_read+0x8cb/0xc70 fs/read_write.c:570
       ksys_read+0x12a/0x240 fs/read_write.c:713
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (mapping.invalidate_lock#2){++++}-{4:4}:
       down_read+0x9b/0x480 kernel/locking/rwsem.c:1524
       filemap_invalidate_lock_shared include/linux/fs.h:922 [inline]
       page_cache_ra_unbounded+0x173/0x7d0 mm/readahead.c:228
       do_page_cache_ra mm/readahead.c:327 [inline]
       page_cache_sync_ra+0x8bd/0x9c0 mm/readahead.c:607
       do_sync_mmap_readahead mm/filemap.c:3237 [inline]
       filemap_fault+0x1e4c/0x2850 mm/filemap.c:3402
       __do_fault+0x10d/0x490 mm/memory.c:4989
       do_cow_fault mm/memory.c:5439 [inline]
       do_fault mm/memory.c:5545 [inline]
       do_pte_missing+0x9b7/0x3ea0 mm/memory.c:4059
       handle_pte_fault mm/memory.c:5888 [inline]
       __handle_mm_fault+0x1043/0x2a50 mm/memory.c:6031
       handle_mm_fault+0x3fa/0xaa0 mm/memory.c:6200
       faultin_page mm/gup.c:1196 [inline]
       __get_user_pages+0x771/0x36f0 mm/gup.c:1491
       __get_user_pages_locked mm/gup.c:1757 [inline]
       __gup_longterm_locked+0x5e7/0x1850 mm/gup.c:2528
       pin_user_pages+0x13c/0x160 mm/gup.c:3598
       xdp_umem_pin_pages net/xdp/xdp_umem.c:105 [inline]
       xdp_umem_reg net/xdp/xdp_umem.c:230 [inline]
       xdp_umem_create+0x73c/0x1270 net/xdp/xdp_umem.c:263
       xsk_setsockopt+0x5b2/0x840 net/xdp/xsk.c:1394
       do_sock_setsockopt+0x224/0x470 net/socket.c:2303
       __sys_setsockopt+0x1a0/0x230 net/socket.c:2328
       __do_sys_setsockopt net/socket.c:2334 [inline]
       __se_sys_setsockopt net/socket.c:2331 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2331
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (&mm->mmap_lock){++++}-{4:4}:
       __might_fault mm/memory.c:6838 [inline]
       __might_fault+0x113/0x190 mm/memory.c:6832
       _copy_from_iter+0x1c6/0x15b0 lib/iov_iter.c:259
       copy_from_iter include/linux/uio.h:228 [inline]
       copy_from_iter_full include/linux/uio.h:245 [inline]
       skb_do_copy_data_nocache include/net/sock.h:2197 [inline]
       skb_copy_to_page_nocache include/net/sock.h:2223 [inline]
       tcp_sendmsg_locked+0x1f4b/0x38d0 net/ipv4/tcp.c:1222
       tcp_sendmsg+0x2e/0x50 net/ipv4/tcp.c:1358
       inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:851
       sock_sendmsg_nosec net/socket.c:718 [inline]
       __sock_sendmsg net/socket.c:733 [inline]
       sock_write_iter+0x4aa/0x5b0 net/socket.c:1137
       new_sync_write fs/read_write.c:591 [inline]
       vfs_write+0x5bd/0x1180 fs/read_write.c:684
       ksys_write+0x205/0x240 fs/read_write.c:736
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (sk_lock-AF_INET){+.+.}-{0:0}:
       lock_sock_nested+0x41/0xf0 net/core/sock.c:3662
       lock_sock include/net/sock.h:1624 [inline]
       inet_shutdown+0x67/0x440 net/ipv4/af_inet.c:905
       nbd_mark_nsock_dead+0xae/0x5d0 drivers/block/nbd.c:318
       sock_shutdown+0x17c/0x280 drivers/block/nbd.c:411
       nbd_start_device_ioctl drivers/block/nbd.c:1537 [inline]
       __nbd_ioctl drivers/block/nbd.c:1602 [inline]
       nbd_ioctl+0xb4e/0xda0 drivers/block/nbd.c:1642
       blkdev_ioctl+0x277/0x6d0 block/ioctl.c:693
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:587 [inline]
       __mutex_lock+0x19a/0xb00 kernel/locking/mutex.c:732
       nbd_handle_cmd drivers/block/nbd.c:1140 [inline]
       nbd_queue_rq+0x423/0x12d0 drivers/block/nbd.c:1204
       blk_mq_dispatch_rq_list+0x43a/0x1e40 block/blk-mq.c:2120
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:170 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:184 [inline]
       __blk_mq_sched_dispatch_requests+0xcec/0x1640 block/blk-mq-sched.c:309
       blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:331
       blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2354
       blk_mq_dispatch_plug_list block/blk-mq.c:2866 [inline]
       blk_mq_flush_plug_list+0x656/0x1c70 block/blk-mq.c:2917
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1213
       blk_finish_plug block/blk-core.c:1240 [inline]
       blk_finish_plug block/blk-core.c:1237 [inline]
       __submit_bio+0x545/0x690 block/blk-core.c:642
       __submit_bio_noacct_mq block/blk-core.c:715 [inline]
       submit_bio_noacct_nocheck+0x663/0xd30 block/blk-core.c:744
       submit_bio_noacct+0x50d/0x1ec0 block/blk-core.c:867
       submit_bh fs/buffer.c:2807 [inline]
       __bread_slow fs/buffer.c:1264 [inline]
       __bread_gfp+0x18c/0x3c0 fs/buffer.c:1488
       sb_bread include/linux/buffer_head.h:346 [inline]
       udf_check_vsd fs/udf/super.c:772 [inline]
       udf_load_vrs+0x8e0/0x1070 fs/udf/super.c:2006
       udf_fill_super+0x791/0x1df0 fs/udf/super.c:2192
       get_tree_bdev_flags+0x38c/0x620 fs/super.c:1636
       vfs_get_tree+0x8e/0x340 fs/super.c:1759
       do_new_mount fs/namespace.c:3878 [inline]
       path_mount+0x14d4/0x1f30 fs/namespace.c:4205
       do_mount fs/namespace.c:4218 [inline]
       __do_sys_mount fs/namespace.c:4429 [inline]
       __se_sys_mount fs/namespace.c:4406 [inline]
       __x64_sys_mount+0x28d/0x310 fs/namespace.c:4406
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:587 [inline]
       __mutex_lock+0x19a/0xb00 kernel/locking/mutex.c:732
       nbd_queue_rq+0xbd/0x12d0 drivers/block/nbd.c:1196
       blk_mq_dispatch_rq_list+0x43a/0x1e40 block/blk-mq.c:2120
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:170 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:184 [inline]
       __blk_mq_sched_dispatch_requests+0xcec/0x1640 block/blk-mq-sched.c:309
       blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:331
       blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2354
       blk_mq_dispatch_plug_list block/blk-mq.c:2866 [inline]
       blk_mq_flush_plug_list+0x656/0x1c70 block/blk-mq.c:2917
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1213
       blk_finish_plug block/blk-core.c:1240 [inline]
       blk_finish_plug block/blk-core.c:1237 [inline]
       __submit_bio+0x545/0x690 block/blk-core.c:642
       __submit_bio_noacct_mq block/blk-core.c:715 [inline]
       submit_bio_noacct_nocheck+0x663/0xd30 block/blk-core.c:744
       submit_bio_noacct+0x50d/0x1ec0 block/blk-core.c:867
       submit_bh fs/buffer.c:2807 [inline]
       __bread_slow fs/buffer.c:1264 [inline]
       __bread_gfp+0x18c/0x3c0 fs/buffer.c:1488
       sb_bread include/linux/buffer_head.h:346 [inline]
       udf_check_vsd fs/udf/super.c:772 [inline]
       udf_load_vrs+0x8e0/0x1070 fs/udf/super.c:2006
       udf_fill_super+0x791/0x1df0 fs/udf/super.c:2192
       get_tree_bdev_flags+0x38c/0x620 fs/super.c:1636
       vfs_get_tree+0x8e/0x340 fs/super.c:1759
       do_new_mount fs/namespace.c:3878 [inline]
       path_mount+0x14d4/0x1f30 fs/namespace.c:4205
       do_mount fs/namespace.c:4218 [inline]
       __do_sys_mount fs/namespace.c:4429 [inline]
       __se_sys_mount fs/namespace.c:4406 [inline]
       __x64_sys_mount+0x28d/0x310 fs/namespace.c:4406
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (set->srcu){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3166 [inline]
       check_prevs_add kernel/locking/lockdep.c:3285 [inline]
       validate_chain kernel/locking/lockdep.c:3909 [inline]
       __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235
       lock_sync+0xa0/0x110 kernel/locking/lockdep.c:5914
       srcu_lock_sync include/linux/srcu.h:173 [inline]
       __synchronize_srcu+0xa1/0x290 kernel/rcu/srcutree.c:1427
       blk_mq_wait_quiesce_done block/blk-mq.c:293 [inline]
       blk_mq_wait_quiesce_done block/blk-mq.c:290 [inline]
       blk_mq_quiesce_queue block/blk-mq.c:313 [inline]
       blk_mq_quiesce_queue+0x149/0x1b0 block/blk-mq.c:308
       elevator_disable+0xe9/0x570 block/elevator.c:661
       blk_mq_elv_switch_none block/blk-mq.c:4951 [inline]
       __blk_mq_update_nr_hw_queues block/blk-mq.c:5018 [inline]
       blk_mq_update_nr_hw_queues+0x41e/0x1360 block/blk-mq.c:5070
       nbd_start_device+0x172/0xcd0 drivers/block/nbd.c:1476
       nbd_start_device_ioctl drivers/block/nbd.c:1527 [inline]
       __nbd_ioctl drivers/block/nbd.c:1602 [inline]
       nbd_ioctl+0x219/0xda0 drivers/block/nbd.c:1642
       blkdev_ioctl+0x277/0x6d0 block/ioctl.c:693
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x260 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:
  set->srcu --> &q->q_usage_counter(io)#54 --> &q->sysfs_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&q->sysfs_lock);
                               lock(&q->q_usage_counter(io)#54);
                               lock(&q->sysfs_lock);
  sync(set->srcu);

 *** DEADLOCK ***

5 locks held by syz.5.667/9051:
 #0: ffff8881433a9998 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_ioctl+0x150/0xda0 drivers/block/nbd.c:1635
 #1: ffff8881433a98d8 (&set->tag_list_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0x8e/0x1360 block/blk-mq.c:5069
 #2: ffff888025df00a8 (&q->q_usage_counter(io)#54){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:215 [inline]
 #2: ffff888025df00a8 (&q->q_usage_counter(io)#54){++++}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5010 [inline]
 #2: ffff888025df00a8 (&q->q_usage_counter(io)#54){++++}-{0:0}, at: blk_mq_update_nr_hw_queues+0x263/0x1360 block/blk-mq.c:5070
 #3: ffff888025df00e0 (&q->q_usage_counter(queue)#38){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave block/blk-mq.c:215 [inline]
 #3: ffff888025df00e0 (&q->q_usage_counter(queue)#38){+.+.}-{0:0}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5010 [inline]
 #3: ffff888025df00e0 (&q->q_usage_counter(queue)#38){+.+.}-{0:0}, at: blk_mq_update_nr_hw_queues+0x263/0x1360 block/blk-mq.c:5070
 #4: ffff888025df05d8 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_mq_elv_switch_none block/blk-mq.c:4937 [inline]
 #4: ffff888025df05d8 (&q->sysfs_lock){+.+.}-{4:4}, at: __blk_mq_update_nr_hw_queues block/blk-mq.c:5018 [inline]
 #4: ffff888025df05d8 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_mq_update_nr_hw_queues+0x4a9/0x1360 block/blk-mq.c:5070

stack backtrace:
CPU: 1 UID: 0 PID: 9051 Comm: syz.5.667 Not tainted 6.14.0-syzkaller-03576-g1e1ba8d23dae #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2079
 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2211
 check_prev_add kernel/locking/lockdep.c:3166 [inline]
 check_prevs_add kernel/locking/lockdep.c:3285 [inline]
 validate_chain kernel/locking/lockdep.c:3909 [inline]
 __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235
 lock_sync+0xa0/0x110 kernel/locking/lockdep.c:5914
 srcu_lock_sync include/linux/srcu.h:173 [inline]
 __synchronize_srcu+0xa1/0x290 kernel/rcu/srcutree.c:1427
 blk_mq_wait_quiesce_done block/blk-mq.c:293 [inline]
 blk_mq_wait_quiesce_done block/blk-mq.c:290 [inline]
 blk_mq_quiesce_queue block/blk-mq.c:313 [inline]
 blk_mq_quiesce_queue+0x149/0x1b0 block/blk-mq.c:308
 elevator_disable+0xe9/0x570 block/elevator.c:661
 blk_mq_elv_switch_none block/blk-mq.c:4951 [inline]
 __blk_mq_update_nr_hw_queues block/blk-mq.c:5018 [inline]
 blk_mq_update_nr_hw_queues+0x41e/0x1360 block/blk-mq.c:5070
 nbd_start_device+0x172/0xcd0 drivers/block/nbd.c:1476
 nbd_start_device_ioctl drivers/block/nbd.c:1527 [inline]
 __nbd_ioctl drivers/block/nbd.c:1602 [inline]
 nbd_ioctl+0x219/0xda0 drivers/block/nbd.c:1642
 blkdev_ioctl+0x277/0x6d0 block/ioctl.c:693
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa62058d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa62143f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa6207a6080 RCX: 00007fa62058d169
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000004
RBP: 00007fa62060e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fa6207a6080 R15: 00007ffcdd076118
 </TASK>
block nbd5: shutting down sockets