syzbot


possible deadlock in __del_gendisk

Status: upstream: reported C repro on 2025/05/26 13:05
Subsystems: block
[Documentation on labels]
Reported-by: syzbot+2e9e529ac0b319316453@syzkaller.appspotmail.com
First crash: 63d, last: now
Cause bisection: introduced by (bisect log) :
commit f1be1788a32e8fa63416ad4518bbd1a85a825c9d
Author: Ming Lei <ming.lei@redhat.com>
Date: Fri Oct 25 00:37:20 2024 +0000

  block: model freeze & enter queue as lock for supporting lockdep

Crash: BUG: MAX_LOCKDEP_KEYS too low! (log)
Repro: C syz .config
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [block?] possible deadlock in __del_gendisk 1 (4) 2025/06/23 04:43
Last patch testing requests (3)
Created Duration User Patch Repo Result
2025/05/29 10:25 15m hdanton@sina.com patch upstream report log
2025/05/28 10:52 6m hdanton@sina.com patch upstream error
2025/05/27 11:25 16m hdanton@sina.com patch upstream report log

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.16.0-rc2-syzkaller-00318-g739a6c93cc75 #0 Not tainted
------------------------------------------------------
kworker/u8:1/13 is trying to acquire lock:
ffff888025836358 (&disk->open_mutex){+.+.}-{4:4}, at: __del_gendisk+0x129/0x9e0 block/genhd.c:706

but task is already holding lock:
ffff88802583c188 (&set->update_nr_hwq_lock){++++}-{4:4}, at: del_gendisk+0xe0/0x160 block/genhd.c:818

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&set->update_nr_hwq_lock){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577
       blk_mq_update_nr_hw_queues+0x3b/0x14c0 block/blk-mq.c:5041
       nbd_start_device+0x16c/0xac0 drivers/block/nbd.c:1476
       nbd_genl_connect+0x1250/0x1930 drivers/block/nbd.c:2201
       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:2534
       genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
       netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
       netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
       netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
       sock_sendmsg_nosec net/socket.c:712 [inline]
       __sock_sendmsg+0x21c/0x270 net/socket.c:727
       ____sys_sendmsg+0x505/0x830 net/socket.c:2566
       ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
       __sys_sendmsg net/socket.c:2652 [inline]
       __do_sys_sendmsg net/socket.c:2657 [inline]
       __se_sys_sendmsg net/socket.c:2655 [inline]
       __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&nbd->config_lock){+.+.}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       __mutex_lock_common kernel/locking/mutex.c:602 [inline]
       __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:747
       refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118
       nbd_config_put+0x2c/0x790 drivers/block/nbd.c:1423
       nbd_release+0xfe/0x140 drivers/block/nbd.c:1735
       bdev_release+0x536/0x650 block/bdev.c:-1
       blkdev_release+0x15/0x20 block/fops.c:684
       __fput+0x44c/0xa70 fs/file_table.c:465
       fput_close_sync+0x119/0x200 fs/file_table.c:570
       __do_sys_close fs/open.c:1589 [inline]
       __se_sys_close fs/open.c:1574 [inline]
       __x64_sys_close+0x7f/0x110 fs/open.c:1574
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&disk->open_mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3168 [inline]
       check_prevs_add kernel/locking/lockdep.c:3287 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       __mutex_lock_common kernel/locking/mutex.c:602 [inline]
       __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:747
       __del_gendisk+0x129/0x9e0 block/genhd.c:706
       del_gendisk+0xe8/0x160 block/genhd.c:819
       nbd_dev_remove drivers/block/nbd.c:268 [inline]
       nbd_dev_remove_work+0x47/0xe0 drivers/block/nbd.c:284
       process_one_work kernel/workqueue.c:3238 [inline]
       process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
       worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
       kthread+0x70e/0x8a0 kernel/kthread.c:464
       ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

Chain exists of:
  &disk->open_mutex --> &nbd->config_lock --> &set->update_nr_hwq_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&set->update_nr_hwq_lock);
                               lock(&nbd->config_lock);
                               lock(&set->update_nr_hwq_lock);
  lock(&disk->open_mutex);

 *** DEADLOCK ***

3 locks held by kworker/u8:1/13:
 #0: ffff888025bf5148 ((wq_completion)nbd-del){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff888025bf5148 ((wq_completion)nbd-del){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3321
 #1: ffffc90000127bc0 ((work_completion)(&nbd->remove_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90000127bc0 ((work_completion)(&nbd->remove_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3321
 #2: ffff88802583c188 (&set->update_nr_hwq_lock){++++}-{4:4}, at: del_gendisk+0xe0/0x160 block/genhd.c:818

stack backtrace:
CPU: 0 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted 6.16.0-rc2-syzkaller-00318-g739a6c93cc75 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: nbd-del nbd_dev_remove_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2046
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3168 [inline]
 check_prevs_add kernel/locking/lockdep.c:3287 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
 __mutex_lock_common kernel/locking/mutex.c:602 [inline]
 __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:747
 __del_gendisk+0x129/0x9e0 block/genhd.c:706
 del_gendisk+0xe8/0x160 block/genhd.c:819
 nbd_dev_remove drivers/block/nbd.c:268 [inline]
 nbd_dev_remove_work+0x47/0xe0 drivers/block/nbd.c:284
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (39101):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/22 10:23 upstream 739a6c93cc75 d6cdfb8a .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce possible deadlock in __del_gendisk
2025/05/27 03:11 upstream ddddf9d64f73 874a1386 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in __del_gendisk
2025/06/21 14:40 net e0fca6f2cebf d6cdfb8a .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 20:40 upstream 25fae0b93d1d fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in __del_gendisk
2025/07/24 13:12 upstream 25fae0b93d1d 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in __del_gendisk
2025/07/24 13:11 upstream 25fae0b93d1d 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in __del_gendisk
2025/07/24 12:10 upstream 01a412d06bc5 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in __del_gendisk
2025/07/24 07:05 upstream 01a412d06bc5 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in __del_gendisk
2025/07/23 23:34 upstream 01a412d06bc5 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in __del_gendisk
2025/07/23 22:59 upstream 01a412d06bc5 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in __del_gendisk
2025/07/23 05:41 upstream 89be9a83ccf1 e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in __del_gendisk
2025/07/22 07:38 upstream 89be9a83ccf1 1555463b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto possible deadlock in __del_gendisk
2025/07/24 23:51 upstream 25fae0b93d1d 65d60d73 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/07/24 23:04 upstream 25fae0b93d1d 65d60d73 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/07/24 22:15 upstream 25fae0b93d1d 65d60d73 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/07/24 09:28 upstream f9af7b5d9349 0c1d6ded .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/07/24 04:31 upstream f9af7b5d9349 0c1d6ded .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/07/24 02:31 upstream f9af7b5d9349 0c1d6ded .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/07/24 00:05 upstream 01a412d06bc5 e0b9ac93 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/07/23 21:57 upstream 01a412d06bc5 e0b9ac93 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/07/23 19:25 upstream 01a412d06bc5 e0b9ac93 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/07/23 18:42 upstream 01a412d06bc5 e0b9ac93 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in __del_gendisk
2025/06/29 03:21 upstream dfba48a70cb6 fc9d8ee5 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in __del_gendisk
2025/07/24 15:25 upstream 25fae0b93d1d 65d60d73 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in __del_gendisk
2025/07/24 06:00 upstream f9af7b5d9349 0c1d6ded .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in __del_gendisk
2025/07/11 12:46 upstream bc9ff192a6c9 3cda49cf .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm64 possible deadlock in __del_gendisk
2025/06/09 07:10 upstream 939f15e640f1 4826c28e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm64-compat possible deadlock in __del_gendisk
2025/07/25 00:37 net 291d5dc80eca fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 21:43 net 291d5dc80eca fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 20:27 net 291d5dc80eca fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 19:27 net 291d5dc80eca fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 18:41 net 291d5dc80eca fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 17:58 net 291d5dc80eca fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 17:10 net 291d5dc80eca fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 16:13 net 291d5dc80eca fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 15:14 net 291d5dc80eca fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 14:14 net 291d5dc80eca 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 11:28 net 14822f782700 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 10:47 net 14822f782700 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 10:12 net 14822f782700 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 08:34 net 14822f782700 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 06:39 net 14822f782700 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 03:43 net 14822f782700 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 01:47 net 14822f782700 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/23 20:28 net 67e9d0b40bd7 e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/23 17:05 net 67e9d0b40bd7 e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in __del_gendisk
2025/07/24 21:46 net-next 94619ea2d933 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/24 05:16 net-next 8aad37d16cff 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/24 03:12 net-next 8aad37d16cff 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/24 01:22 net-next 56613001dfc9 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/24 00:40 net-next 56613001dfc9 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/23 22:28 net-next 56613001dfc9 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/23 21:27 net-next 56613001dfc9 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/23 20:28 net-next 56613001dfc9 e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/23 18:10 net-next 56613001dfc9 e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/23 18:08 net-next 56613001dfc9 e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in __del_gendisk
2025/07/10 08:05 linux-next 835244aba90d 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in __del_gendisk
2025/07/09 09:05 linux-next 58ba80c47402 abade794 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce possible deadlock in __del_gendisk
2025/05/26 12:36 linux-next 3be1a7a31fbd 2d4582d0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in __del_gendisk
2025/05/22 13:03 linux-next 460178e842c7 0919b50b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in __del_gendisk
2025/07/20 07:04 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci aaef6f251176 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in __del_gendisk
2025/07/24 07:48 git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git for-next fda589c28604 0c1d6ded .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-riscv64 possible deadlock in __del_gendisk
* Struck through repros no longer work on HEAD.