======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G U
------------------------------------------------------
syz.1.1346/11768 is trying to acquire lock:
ffff8880338b6f10 (set->srcu){.+.+}-{0:0}, at: srcu_lock_sync include/linux/srcu.h:173 [inline]
ffff8880338b6f10 (set->srcu){.+.+}-{0:0}, at: __synchronize_srcu+0x1c/0x290 kernel/rcu/srcutree.c:1439
but task is already holding lock:
ffff888028c7e808 (&q->elevator_lock){+.+.}-{4:4}, at: elevator_change+0x17d/0x5d0 block/elevator.c:689
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&q->elevator_lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:598 [inline]
__mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
elevator_change+0x17d/0x5d0 block/elevator.c:689
elv_iosched_store+0x315/0x3c0 block/elevator.c:824
queue_attr_store+0x26b/0x310 block/blk-sysfs.c:869
sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142
kernfs_fop_write_iter+0x3af/0x570 fs/kernfs/file.c:352
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x7d3/0x11d0 fs/read_write.c:686
ksys_write+0x12a/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #5 (&q->q_usage_counter(io)#62){++++}-{0:0}:
blk_alloc_queue+0x619/0x760 block/blk-core.c:461
blk_mq_alloc_queue+0x172/0x280 block/blk-mq.c:4399
__blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4446
nbd_dev_add+0x492/0xbb0 drivers/block/nbd.c:1951
nbd_init+0x181/0x320 drivers/block/nbd.c:2688
do_one_initcall+0x120/0x6e0 init/main.c:1283
do_initcall_level init/main.c:1345 [inline]
do_initcalls init/main.c:1361 [inline]
do_basic_setup init/main.c:1380 [inline]
kernel_init_freeable+0x5c2/0x910 init/main.c:1593
kernel_init+0x1c/0x2b0 init/main.c:1483
ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #4 (fs_reclaim){+.+.}-{0:0}:
__fs_reclaim_acquire mm/page_alloc.c:4269 [inline]
fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:4283
might_alloc include/linux/sched/mm.h:318 [inline]
slab_pre_alloc_hook mm/slub.c:4898 [inline]
slab_alloc_node mm/slub.c:5222 [inline]
kmem_cache_alloc_node_noprof+0x5e/0x770 mm/slub.c:5298
__alloc_skb+0x2b2/0x380 net/core/skbuff.c:660
alloc_skb_fclone include/linux/skbuff.h:1433 [inline]
tcp_stream_alloc_skb+0x34/0x560 net/ipv4/tcp.c:912
tcp_sendmsg_locked+0x12d9/0x42e0 net/ipv4/tcp.c:1218
tcp_sendmsg+0x2e/0x50 net/ipv4/tcp.c:1413
inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:853
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
sock_write_iter+0x509/0x610 net/socket.c:1195
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x7d3/0x11d0 fs/read_write.c:686
ksys_write+0x1f8/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 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:3720
lock_sock include/net/sock.h:1679 [inline]
inet_shutdown+0x67/0x440 net/ipv4/af_inet.c:907
nbd_mark_nsock_dead+0xae/0x5d0 drivers/block/nbd.c:318
recv_work+0x671/0xa80 drivers/block/nbd.c:1018
process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
process_scheduled_works kernel/workqueue.c:3346 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
kthread+0x3c2/0x780 kernel/kthread.c:463
ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #2 (&nsock->tx_lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:598 [inline]
__mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
nbd_handle_cmd drivers/block/nbd.c:1140 [inline]
nbd_queue_rq+0x423/0x12d0 drivers/block/nbd.c:1204
blk_mq_dispatch_rq_list+0x416/0x1e20 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+0xcb7/0x15f0 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329
blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2367
blk_mq_dispatch_list+0x514/0x1310 block/blk-mq.c:2928
blk_mq_flush_plug_list block/blk-mq.c:2976 [inline]
blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2948
__blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225
blk_finish_plug block/blk-core.c:1252 [inline]
blk_finish_plug block/blk-core.c:1249 [inline]
__submit_bio+0x545/0x690 block/blk-core.c:651
__submit_bio_noacct_mq block/blk-core.c:724 [inline]
submit_bio_noacct_nocheck+0x53d/0xc10 block/blk-core.c:755
submit_bio_noacct+0xbbb/0x1f60 block/blk-core.c:879
submit_bh fs/buffer.c:2829 [inline]
block_read_full_folio+0x34e/0x850 fs/buffer.c:2447
filemap_read_folio+0xc5/0x2a0 mm/filemap.c:2444
do_read_cache_folio+0x263/0x5c0 mm/filemap.c:4024
read_mapping_folio include/linux/pagemap.h:999 [inline]
read_part_sector+0xd4/0x370 block/partitions/core.c:722
adfspart_check_ICS+0x93/0x940 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+0x720/0x1520 block/partitions/core.c:693
blkdev_get_whole+0x187/0x290 block/bdev.c:748
bdev_open+0x2c7/0xe40 block/bdev.c:957
blkdev_open+0x34e/0x4f0 block/fops.c:701
do_dentry_open+0x982/0x1530 fs/open.c:965
vfs_open+0x82/0x3f0 fs/open.c:1097
do_open fs/namei.c:3975 [inline]
path_openat+0x1de4/0x2cb0 fs/namei.c:4134
do_filp_open+0x20b/0x470 fs/namei.c:4161
do_sys_openat2+0x11b/0x1d0 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+0x174/0x210 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 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:598 [inline]
__mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
nbd_queue_rq+0xbd/0x12d0 drivers/block/nbd.c:1196
blk_mq_dispatch_rq_list+0x416/0x1e20 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+0xcb7/0x15f0 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329
blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2367
blk_mq_dispatch_list+0x514/0x1310 block/blk-mq.c:2928
blk_mq_flush_plug_list block/blk-mq.c:2976 [inline]
blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2948
__blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225
blk_finish_plug block/blk-core.c:1252 [inline]
blk_finish_plug block/blk-core.c:1249 [inline]
__submit_bio+0x545/0x690 block/blk-core.c:651
__submit_bio_noacct_mq block/blk-core.c:724 [inline]
submit_bio_noacct_nocheck+0x53d/0xc10 block/blk-core.c:755
submit_bio_noacct+0xbbb/0x1f60 block/blk-core.c:879
submit_bh fs/buffer.c:2829 [inline]
block_read_full_folio+0x34e/0x850 fs/buffer.c:2447
filemap_read_folio+0xc5/0x2a0 mm/filemap.c:2444
do_read_cache_folio+0x263/0x5c0 mm/filemap.c:4024
read_mapping_folio include/linux/pagemap.h:999 [inline]
read_part_sector+0xd4/0x370 block/partitions/core.c:722
adfspart_check_ICS+0x93/0x940 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+0x720/0x1520 block/partitions/core.c:693
blkdev_get_whole+0x187/0x290 block/bdev.c:748
bdev_open+0x2c7/0xe40 block/bdev.c:957
blkdev_open+0x34e/0x4f0 block/fops.c:701
do_dentry_open+0x982/0x1530 fs/open.c:965
vfs_open+0x82/0x3f0 fs/open.c:1097
do_open fs/namei.c:3975 [inline]
path_openat+0x1de4/0x2cb0 fs/namei.c:4134
do_filp_open+0x20b/0x470 fs/namei.c:4161
do_sys_openat2+0x11b/0x1d0 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+0x174/0x210 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 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:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237
lock_sync+0xa0/0x110 kernel/locking/lockdep.c:5916
srcu_lock_sync include/linux/srcu.h:173 [inline]
__synchronize_srcu+0xa1/0x290 kernel/rcu/srcutree.c:1439
blk_mq_wait_quiesce_done block/blk-mq.c:283 [inline]
blk_mq_wait_quiesce_done block/blk-mq.c:280 [inline]
blk_mq_quiesce_queue block/blk-mq.c:303 [inline]
blk_mq_quiesce_queue+0x149/0x1b0 block/blk-mq.c:298
elevator_switch+0x17d/0x810 block/elevator.c:588
elevator_change+0x391/0x5d0 block/elevator.c:691
elevator_set_default+0x2e9/0x380 block/elevator.c:767
blk_register_queue+0x384/0x4e0 block/blk-sysfs.c:942
__add_disk+0x74a/0xf00 block/genhd.c:528
add_disk_fwnode+0x13f/0x5d0 block/genhd.c:597
add_disk include/linux/blkdev.h:775 [inline]
nbd_dev_add+0x783/0xbb0 drivers/block/nbd.c:1981
nbd_genl_connect+0x8b0/0x1c60 drivers/block/nbd.c:2122
genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x158/0x420 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+0x5a7/0x870 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0xa95/0xc70 net/socket.c:2630
___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
__sys_sendmsg+0x16d/0x220 net/socket.c:2716
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 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)#62 --> &q->elevator_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&q->elevator_lock);
lock(&q->q_usage_counter(io)#62);
lock(&q->elevator_lock);
sync(set->srcu);
*** DEADLOCK ***
6 locks held by syz.1.1346/11768:
#0: ffffffff901a2310 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff901a23c8 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
#1: ffffffff901a23c8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
#1: ffffffff901a23c8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:57 [inline]
#1: ffffffff901a23c8 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x577/0x800 net/netlink/genetlink.c:1209
#2: ffff88807f5329c8 (&set->update_nr_hwq_lock){++++}-{4:4}, at: add_disk_fwnode+0x12e/0x5d0 block/genhd.c:596
#3: ffff888028c7e898 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_register_queue+0x10c/0x4e0 block/blk-sysfs.c:925
#4: ffff888028c7e300 (&q->q_usage_counter(queue)#55){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x15/0x20 block/blk-mq.c:205
#5: ffff888028c7e808 (&q->elevator_lock){+.+.}-{4:4}, at: elevator_change+0x17d/0x5d0 block/elevator.c:689
stack backtrace:
CPU: 0 UID: 0 PID: 11768 Comm: syz.1.1346 Tainted: G U syzkaller #0 PREEMPT(full)
Tainted: [U]=USER
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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:2043
check_noncircular+0x14c/0x170 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+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237
lock_sync+0xa0/0x110 kernel/locking/lockdep.c:5916
srcu_lock_sync include/linux/srcu.h:173 [inline]
__synchronize_srcu+0xa1/0x290 kernel/rcu/srcutree.c:1439
blk_mq_wait_quiesce_done block/blk-mq.c:283 [inline]
blk_mq_wait_quiesce_done block/blk-mq.c:280 [inline]
blk_mq_quiesce_queue block/blk-mq.c:303 [inline]
blk_mq_quiesce_queue+0x149/0x1b0 block/blk-mq.c:298
elevator_switch+0x17d/0x810 block/elevator.c:588
elevator_change+0x391/0x5d0 block/elevator.c:691
elevator_set_default+0x2e9/0x380 block/elevator.c:767
blk_register_queue+0x384/0x4e0 block/blk-sysfs.c:942
__add_disk+0x74a/0xf00 block/genhd.c:528
add_disk_fwnode+0x13f/0x5d0 block/genhd.c:597
add_disk include/linux/blkdev.h:775 [inline]
nbd_dev_add+0x783/0xbb0 drivers/block/nbd.c:1981
nbd_genl_connect+0x8b0/0x1c60 drivers/block/nbd.c:2122
genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x158/0x420 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+0x5a7/0x870 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0xa95/0xc70 net/socket.c:2630
___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
__sys_sendmsg+0x16d/0x220 net/socket.c:2716
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4935f8eec9
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:00007f4936e17038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f49361e5fa0 RCX: 00007f4935f8eec9
RDX: 0000000020040000 RSI: 0000200000000500 RDI: 0000000000000005
RBP: 00007f4936011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f49361e6038 R14: 00007f49361e5fa0 R15: 00007ffe1aba29b8
</TASK>
nbd: socks must be embedded in a SOCK_ITEM attr