From: syzbot <syzbot+68e1f51046d68329940f@syzkaller.appspotmail.com>
To: axboe@kernel.dk, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
song@kernel.org, syzkaller-bugs@googlegroups.com,
yukuai@fnnas.com
Subject: Re: [syzbot] [raid?] possible deadlock in blk_probe_dev
Date: Mon, 14 Sep 2026 16:00:29 -0700 [thread overview]
Message-ID: <6aa87c8d.4c28b7d0.c1bba.0020.GAE@google.com> (raw)
In-Reply-To: <6a6d3cbd.6ce73036.24301b.000d.GAE@google.com>
syzbot has found a reproducer for the following issue on:
HEAD commit: 704340f1cd0d Merge tag 'x86_urgent_for_7.3-rc4' of git://g..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=12ff9905580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c5c3949d762a91f
dashboard link: https://syzkaller.appspot.com/bug?extid=68e1f51046d68329940f
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11a0bc8e580000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+68e1f51046d68329940f@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor197/4337 is trying to acquire lock:
ffff888023113d40 ((wq_completion)md_misc){+.+.}-{0:0}, at: touch_wq_lockdep_map+0x9c/0x1c0 kernel/workqueue.c:4111
but task is already holding lock:
ffffffff8f9b98e0 (major_names_lock){+.+.}-{4:4}, at: blk_probe_dev+0x28/0x1e0 block/genhd.c:885
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (major_names_lock){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
blk_probe_dev+0x28/0x1e0 block/genhd.c:885
blk_request_module+0x16/0xc0 block/genhd.c:901
blkdev_get_no_open+0x9b/0xf0 block/bdev.c:870
bdev_file_open_by_dev block/bdev.c:1091 [inline]
bdev_file_open_by_dev+0x70/0x210 block/bdev.c:1079
md_import_device+0x120/0x360 drivers/md/md.c:3847
md_add_new_disk+0xdbf/0x1820 drivers/md/md.c:7656
md_ioctl+0x2bec/0x36d0 drivers/md/md.c:8499
blkdev_ioctl+0x5ad/0x6f0 block/ioctl.c:798
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (&mddev->reconfig_mutex){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
mddev_lock_nointr drivers/md/md.h:734 [inline]
md_start_sync+0xc4/0xea0 drivers/md/md.c:10275
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
process_scheduled_works kernel/workqueue.c:3479 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #1 ((work_completion)(&mddev->sync_work)){+.+.}-{0:0}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
process_one_work+0xa32/0x1b10 kernel/workqueue.c:3372
process_scheduled_works kernel/workqueue.c:3479 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #0 ((wq_completion)md_misc){+.+.}-{0:0}:
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
check_prevs_add kernel/locking/lockdep.c:3328 [inline]
validate_chain kernel/locking/lockdep.c:3952 [inline]
__lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
touch_wq_lockdep_map+0xad/0x1c0 kernel/workqueue.c:4111
__flush_workqueue+0x131/0x1200 kernel/workqueue.c:4153
md_alloc+0x30/0x10a0 drivers/md/md.c:6334
md_alloc_and_put drivers/md/md.c:6423 [inline]
md_probe drivers/md/md.c:6439 [inline]
md_probe+0x73/0xf0 drivers/md/md.c:6434
blk_probe_dev+0x149/0x1e0 block/genhd.c:888
blk_request_module+0x16/0xc0 block/genhd.c:901
blkdev_get_no_open+0x9b/0xf0 block/bdev.c:870
blkdev_open+0x141/0x4f0 block/fops.c:665
do_dentry_open+0x6ab/0x14d0 fs/open.c:996
vfs_open+0x82/0x3f0 fs/open.c:1101
do_open fs/namei.c:4837 [inline]
path_openat+0x19fa/0x2440 fs/namei.c:5000
do_file_open+0x20e/0x430 fs/namei.c:5029
do_sys_openat2+0x10f/0x1e0 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_sys_openat fs/open.c:1439 [inline]
__se_sys_openat fs/open.c:1434 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Chain exists of:
(wq_completion)md_misc --> &mddev->reconfig_mutex --> major_names_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(major_names_lock);
lock(&mddev->reconfig_mutex);
lock(major_names_lock);
lock((wq_completion)md_misc);
*** DEADLOCK ***
locks held by syz-executor197/4337: 1, last CPU#2:
#0: ffffffff8f9b98e0 (major_names_lock){+.+.}-{4:4}, at: blk_probe_dev+0x28/0x1e0 block/genhd.c:885
stack backtrace:
CPU: 2 UID: 0 PID: 4337 Comm: syz-executor197 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2087
check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
check_prevs_add kernel/locking/lockdep.c:3328 [inline]
validate_chain kernel/locking/lockdep.c:3952 [inline]
__lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
touch_wq_lockdep_map+0xad/0x1c0 kernel/workqueue.c:4111
__flush_workqueue+0x131/0x1200 kernel/workqueue.c:4153
md_alloc+0x30/0x10a0 drivers/md/md.c:6334
md_alloc_and_put drivers/md/md.c:6423 [inline]
md_probe drivers/md/md.c:6439 [inline]
md_probe+0x73/0xf0 drivers/md/md.c:6434
blk_probe_dev+0x149/0x1e0 block/genhd.c:888
blk_request_module+0x16/0xc0 block/genhd.c:901
blkdev_get_no_open+0x9b/0xf0 block/bdev.c:870
blkdev_open+0x141/0x4f0 block/fops.c:665
do_dentry_open+0x6ab/0x14d0 fs/open.c:996
vfs_open+0x82/0x3f0 fs/open.c:1101
do_open fs/namei.c:4837 [inline]
path_openat+0x19fa/0x2440 fs/namei.c:5000
do_file_open+0x20e/0x430 fs/namei.c:5029
do_sys_openat2+0x10f/0x1e0 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_sys_openat fs/open.c:1439 [inline]
__se_sys_openat fs/open.c:1434 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc5b6fe4b37
Code: 48 89 fa 4c 89 df e8 98 1d 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffd92e81700 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000055557809b400 RCX: 00007fc5b6fe4b37
RDX: 0000000000000002 RSI: 00007ffd92e81810 RDI: ffffffffffffff9c
RBP: 00007ffd92e81810 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000004
R13: 0000000000000005 R14: 00007fc5b7049ca0 R15: 0000000000000002
</TASK>
md: async del_gendisk mode will be removed in future, please upgrade to mdadm-4.5+
block device autoloading is deprecated and will be removed.
md: could not open device unknown-block(0,0).
md: md_import_device returned -6
md/raid1:md127: not clean -- starting background reconstruction
md/raid1:md127: active with 2 out of 2 mirrors
md127: detected capacity change from 0 to 20480
md127: detected capacity change from 20480 to 0
md: md127 stopped.
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
prev parent reply other threads:[~2026-09-14 23:00 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-01 0:24 [syzbot] [block?] possible deadlock in blk_probe_dev syzbot
2026-09-14 23:00 ` syzbot [this message]
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