======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/0:5/5964 is trying to acquire lock:
ffff888031aae858 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_check_data_fin+0x284/0x700 net/mptcp/protocol.c:581
but task is already holding lock:
ffff88806e539a58 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1679 [inline]
ffff88806e539a58 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_worker+0x36/0x1160 net/mptcp/protocol.c:2752
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (sk_lock-AF_INET){+.+.}-{0:0}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
lock_sock_nested+0x48/0x100 net/core/sock.c:3720
lock_sock include/net/sock.h:1679 [inline]
inet_shutdown+0x6a/0x390 net/ipv4/af_inet.c:907
nbd_mark_nsock_dead+0x2e9/0x560 drivers/block/nbd.c:318
sock_shutdown+0x15e/0x260 drivers/block/nbd.c:411
nbd_clear_sock drivers/block/nbd.c:1424 [inline]
nbd_config_put+0x342/0x790 drivers/block/nbd.c:1448
nbd_release+0xfe/0x140 drivers/block/nbd.c:1753
bdev_release+0x536/0x650 block/bdev.c:-1
blkdev_release+0x15/0x20 block/fops.c:702
__fput+0x44c/0xa70 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #6 (&nsock->tx_lock){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__mutex_lock_common kernel/locking/mutex.c:598 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
nbd_handle_cmd drivers/block/nbd.c:1140 [inline]
nbd_queue_rq+0x257/0xf10 drivers/block/nbd.c:1204
blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2129
__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+0xda4/0x1570 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2367
blk_mq_dispatch_list+0xd0c/0xe00 include/linux/spinlock.h:-1
blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2976
__blk_flush_plug+0x3d3/0x4b0 block/blk-core.c:1225
blk_finish_plug block/blk-core.c:1252 [inline]
__submit_bio+0x2d3/0x5a0 block/blk-core.c:651
__submit_bio_noacct_mq block/blk-core.c:724 [inline]
submit_bio_noacct_nocheck+0x2fb/0xa50 block/blk-core.c:755
submit_bh fs/buffer.c:2829 [inline]
block_read_full_folio+0x599/0x830 fs/buffer.c:2447
filemap_read_folio+0x117/0x380 mm/filemap.c:2444
do_read_cache_folio+0x350/0x590 mm/filemap.c:4024
read_mapping_folio include/linux/pagemap.h:999 [inline]
read_part_sector+0xb6/0x2b0 block/partitions/core.c:722
adfspart_check_ICS+0xa4/0xa50 block/partitions/acorn.c:360
check_partition block/partitions/core.c:141 [inline]
blk_add_partitions block/partitions/core.c:589 [inline]
bdev_disk_changed+0x75f/0x14b0 block/partitions/core.c:693
blkdev_get_whole+0x380/0x510 block/bdev.c:748
bdev_open+0x31e/0xd30 block/bdev.c:957
blkdev_open+0x457/0x600 block/fops.c:694
do_dentry_open+0x953/0x13f0 fs/open.c:965
vfs_open+0x3b/0x340 fs/open.c:1097
do_open fs/namei.c:3975 [inline]
path_openat+0x2ee5/0x3830 fs/namei.c:4134
do_filp_open+0x1fa/0x410 fs/namei.c:4161
do_sys_openat2+0x121/0x1c0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #5 (&cmd->lock){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__mutex_lock_common kernel/locking/mutex.c:598 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
nbd_queue_rq+0xc8/0xf10 drivers/block/nbd.c:1196
blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2129
__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+0xda4/0x1570 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2367
blk_mq_dispatch_list+0xd0c/0xe00 include/linux/spinlock.h:-1
blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2976
__blk_flush_plug+0x3d3/0x4b0 block/blk-core.c:1225
blk_finish_plug block/blk-core.c:1252 [inline]
__submit_bio+0x2d3/0x5a0 block/blk-core.c:651
__submit_bio_noacct_mq block/blk-core.c:724 [inline]
submit_bio_noacct_nocheck+0x2fb/0xa50 block/blk-core.c:755
submit_bh fs/buffer.c:2829 [inline]
block_read_full_folio+0x599/0x830 fs/buffer.c:2447
filemap_read_folio+0x117/0x380 mm/filemap.c:2444
do_read_cache_folio+0x350/0x590 mm/filemap.c:4024
read_mapping_folio include/linux/pagemap.h:999 [inline]
read_part_sector+0xb6/0x2b0 block/partitions/core.c:722
adfspart_check_ICS+0xa4/0xa50 block/partitions/acorn.c:360
check_partition block/partitions/core.c:141 [inline]
blk_add_partitions block/partitions/core.c:589 [inline]
bdev_disk_changed+0x75f/0x14b0 block/partitions/core.c:693
blkdev_get_whole+0x380/0x510 block/bdev.c:748
bdev_open+0x31e/0xd30 block/bdev.c:957
blkdev_open+0x457/0x600 block/fops.c:694
do_dentry_open+0x953/0x13f0 fs/open.c:965
vfs_open+0x3b/0x340 fs/open.c:1097
do_open fs/namei.c:3975 [inline]
path_openat+0x2ee5/0x3830 fs/namei.c:4134
do_filp_open+0x1fa/0x410 fs/namei.c:4161
do_sys_openat2+0x121/0x1c0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #4 (set->srcu){.+.+}-{0:0}:
lock_sync+0xba/0x160 kernel/locking/lockdep.c:5916
srcu_lock_sync include/linux/srcu.h:173 [inline]
__synchronize_srcu+0x96/0x3a0 kernel/rcu/srcutree.c:1429
elevator_switch+0x12b/0x640 block/elevator.c:588
elevator_change+0x315/0x4c0 block/elevator.c:691
elevator_set_default+0x186/0x260 block/elevator.c:767
blk_register_queue+0x34e/0x3f0 block/blk-sysfs.c:942
__add_disk+0x677/0xd50 block/genhd.c:528
add_disk_fwnode+0xfc/0x480 block/genhd.c:597
add_disk include/linux/blkdev.h:775 [inline]
nbd_dev_add+0x717/0xae0 drivers/block/nbd.c:1981
nbd_init+0x168/0x1f0 drivers/block/nbd.c:2688
do_one_initcall+0x236/0x820 init/main.c:1283
do_initcall_level+0x104/0x190 init/main.c:1345
do_initcalls+0x59/0xa0 init/main.c:1361
kernel_init_freeable+0x334/0x4b0 init/main.c:1593
kernel_init+0x1d/0x1d0 init/main.c:1483
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #3 (&q->elevator_lock){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__mutex_lock_common kernel/locking/mutex.c:598 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
elevator_change+0x1e5/0x4c0 block/elevator.c:689
elevator_set_none+0x42/0xb0 block/elevator.c:782
blk_mq_elv_switch_none block/blk-mq.c:5032 [inline]
__blk_mq_update_nr_hw_queues block/blk-mq.c:5075 [inline]
blk_mq_update_nr_hw_queues+0x598/0x1ab0 block/blk-mq.c:5133
nbd_start_device+0x17f/0xb10 drivers/block/nbd.c:1486
nbd_genl_connect+0x135b/0x18f0 drivers/block/nbd.c:2236
genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
sock_sendmsg_nosec net/socket.c:714 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:729
____sys_sendmsg+0x505/0x830 net/socket.c:2617
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2671
__sys_sendmsg net/socket.c:2703 [inline]
__do_sys_sendmsg net/socket.c:2708 [inline]
__se_sys_sendmsg net/socket.c:2706 [inline]
__x64_sys_sendmsg+0x19b/0x260 net/socket.c:2706
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (&q->q_usage_counter(io)#50){++++}-{0:0}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
blk_alloc_queue+0x538/0x620 block/blk-core.c:461
blk_mq_alloc_queue block/blk-mq.c:4399 [inline]
__blk_mq_alloc_disk+0x15c/0x340 block/blk-mq.c:4446
nbd_dev_add+0x46c/0xae0 drivers/block/nbd.c:1951
nbd_init+0x168/0x1f0 drivers/block/nbd.c:2688
do_one_initcall+0x236/0x820 init/main.c:1283
do_initcall_level+0x104/0x190 init/main.c:1345
do_initcalls+0x59/0xa0 init/main.c:1361
kernel_init_freeable+0x334/0x4b0 init/main.c:1593
kernel_init+0x1d/0x1d0 init/main.c:1483
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #1 (fs_reclaim){+.+.}-{0:0}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__fs_reclaim_acquire mm/page_alloc.c:4269 [inline]
fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4283
might_alloc include/linux/sched/mm.h:318 [inline]
slab_pre_alloc_hook mm/slub.c:4896 [inline]
slab_alloc_node mm/slub.c:5220 [inline]
kmem_cache_alloc_node_noprof+0x48/0x710 mm/slub.c:5296
__alloc_skb+0x112/0x2d0 net/core/skbuff.c:660
alloc_skb_fclone include/linux/skbuff.h:1433 [inline]
tcp_stream_alloc_skb+0x3d/0x340 net/ipv4/tcp.c:912
tcp_connect+0x14b8/0x5060 net/ipv4/tcp_output.c:4303
tcp_v4_connect+0x1110/0x1a00 net/ipv4/tcp_ipv4.c:347
mptcp_connect+0x56b/0x830 net/mptcp/protocol.c:3775
__inet_stream_connect+0x2ae/0xe70 net/ipv4/af_inet.c:679
inet_stream_connect+0x66/0xa0 net/ipv4/af_inet.c:750
__sys_connect_file net/socket.c:2089 [inline]
__sys_connect+0x316/0x440 net/socket.c:2108
__do_sys_connect net/socket.c:2114 [inline]
__se_sys_connect net/socket.c:2111 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2111
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (k-sk_lock-AF_INET){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
lock_sock_fast include/net/sock.h:1711 [inline]
mptcp_shutdown_subflows+0x8b/0x130 net/mptcp/protocol.c:383
mptcp_check_data_fin+0x284/0x700 net/mptcp/protocol.c:581
mptcp_worker+0x4d1/0x1160 net/mptcp/protocol.c:2763
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
other info that might help us debug this:
Chain exists of:
k-sk_lock-AF_INET --> &nsock->tx_lock --> sk_lock-AF_INET
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(sk_lock-AF_INET);
lock(&nsock->tx_lock);
lock(sk_lock-AF_INET);
lock(k-sk_lock-AF_INET);
*** DEADLOCK ***
3 locks held by kworker/0:5/5964:
#0: ffff88801b019948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88801b019948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc9000460fba0 ((work_completion)(&msk->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc9000460fba0 ((work_completion)(&msk->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffff88806e539a58 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1679 [inline]
#2: ffff88806e539a58 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_worker+0x36/0x1160 net/mptcp/protocol.c:2752
stack backtrace:
CPU: 0 UID: 0 PID: 5964 Comm: kworker/0:5 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events mptcp_worker
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
lock_sock_fast include/net/sock.h:1711 [inline]
mptcp_shutdown_subflows+0x8b/0x130 net/mptcp/protocol.c:383
mptcp_check_data_fin+0x284/0x700 net/mptcp/protocol.c:581
mptcp_worker+0x4d1/0x1160 net/mptcp/protocol.c:2763
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>