possible deadlock in raid_dtr

Status: upstream: reported on 2026/11/06 03:26
Reported-by: syzbot+8fd9ae816e8304bf9b2e@syzkaller.appspotmail.com
First crash: 7d10h, last: 7d10h
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in raid_dtr 4 1 16h16m 16h15m 0/3 upstream: reported on 2026/11/12 21:10
linux-6.1 possible deadlock in raid_dtr 4 1 3d04h 3d04h 0/3 upstream: reported on 2026/11/10 09:22

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.3359/17190 is trying to acquire lock:
ffff88801beff938 ((wq_completion)md_misc){+.+.}-{0:0}, at: touch_wq_lockdep_map kernel/workqueue.c:3183 [inline]
ffff88801beff938 ((wq_completion)md_misc){+.+.}-{0:0}, at: __flush_workqueue+0x150/0x1380 kernel/workqueue.c:3213

but task is already holding lock:
ffff88807d4c83b8 (&mddev->reconfig_mutex){+.+.}-{3:3}, at: mddev_lock_nointr drivers/md/md.h:601 [inline]
ffff88807d4c83b8 (&mddev->reconfig_mutex){+.+.}-{3:3}, at: raid_dtr+0x47/0x70 drivers/md/dm-raid.c:3315

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&mddev->reconfig_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x135/0xce0 kernel/locking/mutex.c:747
       mddev_lock drivers/md/md.h:593 [inline]
       array_state_store+0x2ef/0xb00 drivers/md/md.c:4572
       md_attr_store+0x19c/0x390 drivers/md/md.c:5756
       kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352
       call_write_iter include/linux/fs.h:2019 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x474/0x9a0 fs/read_write.c:584
       ksys_write+0x151/0x260 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (kn->active#72){++++}-{0:0}:
       kernfs_drain+0x31e/0x6d0 fs/kernfs/dir.c:500
       __kernfs_remove+0x426/0x830 fs/kernfs/dir.c:1486
       kernfs_remove_by_name_ns+0xdc/0x150 fs/kernfs/dir.c:1695
       kernfs_remove_by_name include/linux/kernfs.h:624 [inline]
       remove_files fs/sysfs/group.c:28 [inline]
       sysfs_remove_group+0x101/0x290 fs/sysfs/group.c:292
       sysfs_remove_groups+0x54/0xa0 fs/sysfs/group.c:316
       __kobject_del+0x83/0x2e0 lib/kobject.c:595
       kobject_cleanup lib/kobject.c:680 [inline]
       kobject_release lib/kobject.c:720 [inline]
       kref_put include/linux/kref.h:65 [inline]
       kobject_put+0x233/0x450 lib/kobject.c:737
       process_one_work kernel/workqueue.c:2657 [inline]
       process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
       worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
       kthread+0x2fa/0x390 kernel/kthread.c:388
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

-> #1 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}:
       process_one_work kernel/workqueue.c:2633 [inline]
       process_scheduled_works+0x9ab/0x1600 kernel/workqueue.c:2734
       worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
       kthread+0x2fa/0x390 kernel/kthread.c:388
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

-> #0 ((wq_completion)md_misc){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3162 [inline]
       check_prevs_add kernel/locking/lockdep.c:3281 [inline]
       validate_chain kernel/locking/lockdep.c:3897 [inline]
       __lock_acquire+0x3a07/0x7eb0 kernel/locking/lockdep.c:5171
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5790
       touch_wq_lockdep_map kernel/workqueue.c:3183 [inline]
       __flush_workqueue+0x169/0x1380 kernel/workqueue.c:3213
       __md_stop+0x1a9/0x340 drivers/md/md.c:6476
       md_stop+0x7a/0xc0 drivers/md/md.c:6502
       raid_dtr+0x4f/0x70 drivers/md/dm-raid.c:3316
       dm_table_destroy+0x19d/0x460 drivers/md/dm-table.c:197
       dm_hash_remove_all+0x10e/0x200 drivers/md/dm-ioctl.c:367
       remove_all+0x50/0xa0 drivers/md/dm-ioctl.c:532
       ctl_ioctl drivers/md/dm-ioctl.c:2115 [inline]
       dm_ctl_ioctl+0x975/0xd00 drivers/md/dm-ioctl.c:2137
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  (wq_completion)md_misc --> kn->active#72 --> &mddev->reconfig_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mddev->reconfig_mutex);
                               lock(kn->active#72);
                               lock(&mddev->reconfig_mutex);
  lock((wq_completion)md_misc);

 *** DEADLOCK ***

1 lock held by syz.3.3359/17190:
 #0: ffff88807d4c83b8 (&mddev->reconfig_mutex){+.+.}-{3:3}, at: mddev_lock_nointr drivers/md/md.h:601 [inline]
 #0: ffff88807d4c83b8 (&mddev->reconfig_mutex){+.+.}-{3:3}, at: raid_dtr+0x47/0x70 drivers/md/dm-raid.c:3315

stack backtrace:
CPU: 0 PID: 17190 Comm: syz.3.3359 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2215
 check_prev_add kernel/locking/lockdep.c:3162 [inline]
 check_prevs_add kernel/locking/lockdep.c:3281 [inline]
 validate_chain kernel/locking/lockdep.c:3897 [inline]
 __lock_acquire+0x3a07/0x7eb0 kernel/locking/lockdep.c:5171
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5790
 touch_wq_lockdep_map kernel/workqueue.c:3183 [inline]
 __flush_workqueue+0x169/0x1380 kernel/workqueue.c:3213
 __md_stop+0x1a9/0x340 drivers/md/md.c:6476
 md_stop+0x7a/0xc0 drivers/md/md.c:6502
 raid_dtr+0x4f/0x70 drivers/md/dm-raid.c:3316
 dm_table_destroy+0x19d/0x460 drivers/md/dm-table.c:197
 dm_hash_remove_all+0x10e/0x200 drivers/md/dm-ioctl.c:367
 remove_all+0x50/0xa0 drivers/md/dm-ioctl.c:532
 ctl_ioctl drivers/md/dm-ioctl.c:2115 [inline]
 dm_ctl_ioctl+0x975/0xd00 drivers/md/dm-ioctl.c:2137
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa975f9fb19
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa976eab028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa976225fa0 RCX: 00007fa975f9fb19
RDX: 0000200000000b80 RSI: 00000000c138fd01 RDI: 0000000000000006
RBP: 00007fa976037b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa976226038 R14: 00007fa976225fa0 R15: 00007ffdbfb1a8e8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/11/06 03:25 linux-6.6.y b5a1dc3ad482 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in raid_dtr
* Struck through repros no longer work on HEAD.