From: syzbot <syzbot+fb0ff9bfe34ad282ebd4@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?] [block?] possible deadlock in blk_request_module (2)
Date: Thu, 15 Oct 2026 13:08:23 -0700 [thread overview]
Message-ID: <6ad132b7.7952420f.283480.00dc.GAE@google.com> (raw)
In-Reply-To: <6a14aff8.050a0220.2385e8.0019.GAE@google.com>
syzbot has found a reproducer for the following issue on:
HEAD commit: b810335a0699 Add linux-next specific files for 20261015
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1605ffd1580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1b8bbfb3c8b8bab9
dashboard link: https://syzkaller.appspot.com/bug?extid=fb0ff9bfe34ad282ebd4
compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1505ffd1580000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fb0ff9bfe34ad282ebd4@syzkaller.appspotmail.com
md/raid1:md125: active with 1 out of 1 mirrors
md125: detected capacity change from 0 to 8192
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor123/5954 is trying to acquire lock:
ffffffff90960c40 (major_names_lock){+.+.}-{4:4}, at: blk_probe_dev block/genhd.c:885 [inline]
ffffffff90960c40 (major_names_lock){+.+.}-{4:4}, at: blk_request_module+0x35/0x2a0 block/genhd.c:901
but task is already holding lock:
ffff8880236d8358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: mddev_lock drivers/md/md.h:713 [inline]
ffff8880236d8358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: mddev_suspend_and_lock+0x48/0xf0 drivers/md/md.h:1019
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&mddev->reconfig_mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
mddev_lock_nointr drivers/md/md.h:734 [inline]
md_start_sync+0x179/0x1010 drivers/md/md.c:10275
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
-> #2 ((work_completion)(&mddev->sync_work)){+.+.}-{0:0}:
process_one_work kernel/workqueue.c:3471 [inline]
process_scheduled_works+0xc03/0x1630 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
-> #1 ((wq_completion)md_misc){+.+.}-{0:0}:
touch_wq_lockdep_map+0xcb/0x180 kernel/workqueue.c:4272
__flush_workqueue+0x148/0x10b0 kernel/workqueue.c:4314
md_alloc+0x32/0xf20 drivers/md/md.c:6334
md_alloc_and_put+0x1a/0x1f0 drivers/md/md.c:6423
blk_probe_dev block/genhd.c:888 [inline]
blk_request_module+0x27d/0x2a0 block/genhd.c:-1
blkdev_get_no_open+0x3f/0xe0 block/bdev.c:870
blkdev_open+0x1d7/0x600 block/fops.c:677
do_dentry_open+0x80e/0x1360 fs/open.c:1000
vfs_open_consume+0x4a/0x350 fs/open.c:1131
do_open fs/namei.c:4892 [inline]
path_openat+0x16fc/0x20f0 fs/namei.c:5057
do_file_open+0x23e/0x4a0 fs/namei.c:5086
do_sys_openat2+0x115/0x200 fs/open.c:1442
do_sys_open fs/open.c:1448 [inline]
__do_sys_openat fs/open.c:1788 [inline]
__se_sys_openat fs/open.c:1783 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1783
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (major_names_lock){+.+.}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3209 [inline]
check_prevs_add kernel/locking/lockdep.c:3328 [inline]
validate_chain kernel/locking/lockdep.c:3952 [inline]
__lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288
lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
blk_probe_dev block/genhd.c:885 [inline]
blk_request_module+0x35/0x2a0 block/genhd.c:901
blkdev_get_no_open+0x3f/0xe0 block/bdev.c:870
bdev_file_open_by_dev+0xa0/0x240 block/bdev.c:1091
md_import_device+0x2e9/0x650 drivers/md/md.c:3847
md_add_new_disk+0x669/0x1850 drivers/md/md.c:7549
md_ioctl+0x2005/0x2610 drivers/md/md.c:8499
blkdev_ioctl+0x5e3/0x740 block/ioctl.c:798
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 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:
major_names_lock --> (work_completion)(&mddev->sync_work) --> &mddev->reconfig_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&mddev->reconfig_mutex);
lock((work_completion)(&mddev->sync_work));
lock(&mddev->reconfig_mutex);
lock(major_names_lock);
*** DEADLOCK ***
locks held by syz-executor123/5954: 1, last CPU#0:
#0: ffff8880236d8358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: mddev_lock drivers/md/md.h:713 [inline]
#0: ffff8880236d8358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: mddev_suspend_and_lock+0x48/0xf0 drivers/md/md.h:1019
stack backtrace:
CPU: 0 UID: 0 PID: 5954 Comm: syz-executor123 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2087
check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2219
check_prev_add kernel/locking/lockdep.c:3209 [inline]
check_prevs_add kernel/locking/lockdep.c:3328 [inline]
validate_chain kernel/locking/lockdep.c:3952 [inline]
__lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288
lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
blk_probe_dev block/genhd.c:885 [inline]
blk_request_module+0x35/0x2a0 block/genhd.c:901
blkdev_get_no_open+0x3f/0xe0 block/bdev.c:870
bdev_file_open_by_dev+0xa0/0x240 block/bdev.c:1091
md_import_device+0x2e9/0x650 drivers/md/md.c:3847
md_add_new_disk+0x669/0x1850 drivers/md/md.c:7549
md_ioctl+0x2005/0x2610 drivers/md/md.c:8499
blkdev_ioctl+0x5e3/0x740 block/ioctl.c:798
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4e137daefb
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007ffea3973750 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4e137daefb
RDX: 00007ffea39737d0 RSI: 0000000040140921 RDI: 0000000000000005
RBP: 0000000000000005 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
R13: 00007ffea3973830 R14: 00007f4e1385fcc0 R15: 0000000000000002
</TASK>
md: could not open device unknown-block(0,0).
md: md_import_device returned -6
---
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:[~2026-10-15 20:08 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-25 20:24 [syzbot] [block?] possible deadlock in blk_request_module (2) syzbot
2026-10-15 20:08 ` syzbot [this message]
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