Re: [syzbot] possible deadlock in wg_ratelimiter_uninit

[syzbot <syzbot+72fceb8393e04ce876d9@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in inet_shutdown

block nbd0: Receive control failed (result -32)
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u9:0/53 is trying to acquire lock:
ffff888079910fa0 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1717 [inline]
ffff888079910fa0 (sk_lock-AF_INET){+.+.}-{0:0}, at: inet_shutdown+0x6a/0x390 net/ipv4/af_inet.c:911

but task is already holding lock:
ffff88807468d668 (&nsock->tx_lock){+.+.}-{4:4}, at: recv_work+0x1cff/0x1e30 drivers/block/nbd.c:1029

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #6 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
       nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
       nbd_queue_rq+0x373/0xff0 drivers/block/nbd.c:1207
       blk_mq_dispatch_rq_list+0x499/0x1990 block/blk-mq.c:2141
       __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+0xd36/0x1580 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
       blk_mq_run_work_fn+0x167/0x2f0 block/blk-mq.c:2556
       process_one_work kernel/workqueue.c:3495 [inline]
       process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578
       worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659
       kthread+0x38b/0x480 kernel/kthread.c:436
       ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #5 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
       nbd_queue_rq+0xc1/0xff0 drivers/block/nbd.c:1199
       blk_mq_dispatch_rq_list+0x499/0x1990 block/blk-mq.c:2141
       __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+0xd36/0x1580 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
       blk_mq_run_work_fn+0x167/0x2f0 block/blk-mq.c:2556
       process_one_work kernel/workqueue.c:3495 [inline]
       process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578
       worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659
       kthread+0x38b/0x480 kernel/kthread.c:436
       ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #4 (set->srcu){.+.+}-{0:0}:
       srcu_lock_sync include/linux/srcu.h:261 [inline]
       __synchronize_srcu+0xca/0x2f0 kernel/rcu/srcutree.c:1662
       elevator_switch+0x1e8/0x7b0 block/elevator.c:576
       elevator_change+0x2fa/0x480 block/elevator.c:681
       elevator_set_default+0x375/0x440 block/elevator.c:754
       blk_register_queue+0x404/0x4f0 block/blk-sysfs.c:992
       __add_disk+0x6b8/0xdb0 block/genhd.c:531
       add_disk_fwnode+0x100/0x3a0 block/genhd.c:600
       add_disk include/linux/blkdev.h:799 [inline]
       nbd_dev_add+0x733/0xb60 drivers/block/nbd.c:2026
       nbd_init+0x168/0x1f0 drivers/block/nbd.c:2743
       do_one_initcall+0x250/0x870 init/main.c:1419
       do_initcall_level+0x10a/0x1a0 init/main.c:1481
    


Tested on:

commit:         067c5c24 Merge tag 'page_alloc-for-7.4-rc2' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=119221a1580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d44b06612b68f56
dashboard link: https://syzkaller.appspot.com/bug?extid=72fceb8393e04ce876d9
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=113f2fa5580000