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Message-ID: <68f512d5.a70a0220.205af.0019.GAE@google.com>
Date: Sun, 19 Oct 2025 09:33:25 -0700
From: syzbot <syzbot+a0cafc3f8cfebb67a088@...kaller.appspotmail.com>
To: abbotti@....co.uk, gregkh@...uxfoundation.org,
hsweeten@...ionengravers.com, linux-kernel@...r.kernel.org,
syzkaller-bugs@...glegroups.com, tj@...nel.org
Subject: [syzbot] [comedi?] inconsistent lock state in valid_state (6)
Hello,
syzbot found the following issue on:
HEAD commit: 93f3bab4310d Add linux-next specific files for 20251017
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16f3f5e2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=13d823f401f2bb44
dashboard link: https://syzkaller.appspot.com/bug?extid=a0cafc3f8cfebb67a088
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bfa9b5bd373e/disk-93f3bab4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0f36271412fd/vmlinux-93f3bab4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d9cdcb1778ab/bzImage-93f3bab4.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a0cafc3f8cfebb67a088@...kaller.appspotmail.com
================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
syz.6.2492/15234 [HC0[0]:SC0[0]:HE1:SE1] takes:
ffffffff8b04aec8 ((&dev->delay)){+.?.}-{0:0}, at: kernfs_remove_by_name_ns+0x3d/0x130 fs/kernfs/dir.c:1712
{IN-SOFTIRQ-W} state was registered at:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
call_timer_fn+0xdb/0x5f0 kernel/time/timer.c:1744
expire_timers kernel/time/timer.c:1798 [inline]
__run_timers kernel/time/timer.c:2372 [inline]
__run_timer_base+0x61a/0x860 kernel/time/timer.c:2384
run_timer_base kernel/time/timer.c:2393 [inline]
run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403
handle_softirqs+0x286/0x870 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:723
irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
debug_lockdep_rcu_enabled+0xd/0x40 kernel/rcu/update.c:320
mt_slot lib/maple_tree.c:734 [inline]
mas_slot lib/maple_tree.c:767 [inline]
mt_validate_nulls lib/maple_tree.c:7122 [inline]
mt_validate+0x3d7c/0x4390 lib/maple_tree.c:7177
validate_mm+0xae/0x4a0 mm/vma.c:651
__split_vma+0x8bd/0xa00 mm/vma.c:569
vms_gather_munmap_vmas+0x2e2/0x12e0 mm/vma.c:1359
__mmap_setup mm/vma.c:2375 [inline]
__mmap_region mm/vma.c:2669 [inline]
mmap_region+0x724/0x1c70 mm/vma.c:2764
do_mmap+0xc45/0x10d0 mm/mmap.c:558
vm_mmap_pgoff+0x2a6/0x4d0 mm/util.c:581
ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:604
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
irq event stamp: 487
hardirqs last enabled at (487): [<ffffffff82263c7d>] kasan_quarantine_put+0xdd/0x220 mm/kasan/quarantine.c:234
hardirqs last disabled at (486): [<ffffffff82263bdd>] kasan_quarantine_put+0x3d/0x220 mm/kasan/quarantine.c:207
softirqs last enabled at (352): [<ffffffff81693698>] local_bh_enable include/linux/bottom_half.h:33 [inline]
softirqs last enabled at (352): [<ffffffff81693698>] fpregs_unlock arch/x86/include/asm/fpu/api.h:77 [inline]
softirqs last enabled at (352): [<ffffffff81693698>] kernel_fpu_end+0xc8/0x120 arch/x86/kernel/fpu/core.c:479
softirqs last disabled at (350): [<ffffffff816932da>] local_bh_disable include/linux/bottom_half.h:20 [inline]
softirqs last disabled at (350): [<ffffffff816932da>] fpregs_lock arch/x86/include/asm/fpu/api.h:69 [inline]
softirqs last disabled at (350): [<ffffffff816932da>] kernel_fpu_begin_mask+0xba/0x3a0 arch/x86/kernel/fpu/core.c:448
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock((&dev->delay));
<Interrupt>
lock((&dev->delay));
*** DEADLOCK ***
2 locks held by syz.6.2492/15234:
#0: ffff88814c6558f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_unlocked_ioctl+0x13a/0x1020 drivers/comedi/comedi_fops.c:2166
#1: ffff88814c655990 (&dev->attach_lock){++++}-{4:4}, at: do_devconfig_ioctl drivers/comedi/comedi_fops.c:841 [inline]
#1: ffff88814c655990 (&dev->attach_lock){++++}-{4:4}, at: comedi_unlocked_ioctl+0x615/0x1020 drivers/comedi/comedi_fops.c:2178
stack backtrace:
CPU: 1 UID: 0 PID: 15234 Comm: syz.6.2492 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_usage_bug+0x297/0x2e0 kernel/locking/lockdep.c:4042
valid_state+0xc3/0xf0 kernel/locking/lockdep.c:4056
mark_lock_irq+0x36/0x390 kernel/locking/lockdep.c:4267
mark_lock+0x11b/0x190 kernel/locking/lockdep.c:4753
mark_usage kernel/locking/lockdep.c:-1 [inline]
__lock_acquire+0x9e2/0xd20 kernel/locking/lockdep.c:5191
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
kernfs_remove_by_name_ns+0x3d/0x130 fs/kernfs/dir.c:1712
remove_bind_files drivers/base/bus.c:605 [inline]
bus_remove_driver+0x198/0x2f0 drivers/base/bus.c:743
comedi_device_detach_locked+0x178/0x750 drivers/comedi/drivers.c:207
do_devconfig_ioctl drivers/comedi/comedi_fops.c:848 [inline]
comedi_unlocked_ioctl+0xcde/0x1020 drivers/comedi/comedi_fops.c:2178
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:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f952678efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f95249cd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f95269e6090 RCX: 00007f952678efc9
RDX: 0000000000000000 RSI: 0000000040946400 RDI: 0000000000000007
RBP: 00007f9526811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f95269e6128 R14: 00007f95269e6090 R15: 00007fff0c18c5f8
</TASK>
BUG: unable to handle page fault for address: ffffffff8b04ae58
#PF: supervisor write access in kernel mode
#PF: error_code(0x0003) - permissions violation
PGD df3d067 P4D df3d067 PUD df3e063 PMD b0001a1
Oops: Oops: 0003 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 15234 Comm: syz.6.2492 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:arch_atomic64_try_cmpxchg arch/x86/include/asm/atomic64_64.h:101 [inline]
RIP: 0010:raw_atomic64_try_cmpxchg_acquire include/linux/atomic/atomic-arch-fallback.h:4296 [inline]
RIP: 0010:raw_atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-long.h:1482 [inline]
RIP: 0010:atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4458 [inline]
RIP: 0010:rwsem_write_trylock kernel/locking/rwsem.c:268 [inline]
RIP: 0010:__down_write_common kernel/locking/rwsem.c:1316 [inline]
RIP: 0010:__down_write kernel/locking/rwsem.c:1326 [inline]
RIP: 0010:down_write+0xd1/0x1f0 kernel/locking/rwsem.c:1591
Code: 24 20 00 00 00 00 48 89 df be 08 00 00 00 e8 06 1b dd f6 4c 89 f7 be 08 00 00 00 e8 f9 1a dd f6 48 8b 44 24 20 b9 01 00 00 00 <f0> 48 0f b1 0b 0f 85 c2 00 00 00 48 c7 c0 90 0b 9e 8f 48 c1 e8 03
RSP: 0018:ffffc9000bc379a0 EFLAGS: 00010256
RAX: 0000000000000000 RBX: ffffffff8b04ae58 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9000bc379c0
RBP: ffffc9000bc37a28 R08: ffffc9000bc379c7 R09: 1ffff92001786f38
R10: dffffc0000000000 R11: fffff52001786f39 R12: 1ffff92001786f34
R13: dffffc0000000000 R14: ffffc9000bc379c0 R15: dffffc0000000000
FS: 00007f95249cd6c0(0000) GS:ffff888125e1f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffff8b04ae58 CR3: 0000000078bb2000 CR4: 00000000003526f0
Call Trace:
<TASK>
kernfs_remove_by_name_ns+0x3d/0x130 fs/kernfs/dir.c:1712
remove_bind_files drivers/base/bus.c:605 [inline]
bus_remove_driver+0x198/0x2f0 drivers/base/bus.c:743
comedi_device_detach_locked+0x178/0x750 drivers/comedi/drivers.c:207
do_devconfig_ioctl drivers/comedi/comedi_fops.c:848 [inline]
comedi_unlocked_ioctl+0xcde/0x1020 drivers/comedi/comedi_fops.c:2178
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:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f952678efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f95249cd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f95269e6090 RCX: 00007f952678efc9
RDX: 0000000000000000 RSI: 0000000040946400 RDI: 0000000000000007
RBP: 00007f9526811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f95269e6128 R14: 00007f95269e6090 R15: 00007fff0c18c5f8
</TASK>
Modules linked in:
CR2: ffffffff8b04ae58
---[ end trace 0000000000000000 ]---
RIP: 0010:arch_atomic64_try_cmpxchg arch/x86/include/asm/atomic64_64.h:101 [inline]
RIP: 0010:raw_atomic64_try_cmpxchg_acquire include/linux/atomic/atomic-arch-fallback.h:4296 [inline]
RIP: 0010:raw_atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-long.h:1482 [inline]
RIP: 0010:atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4458 [inline]
RIP: 0010:rwsem_write_trylock kernel/locking/rwsem.c:268 [inline]
RIP: 0010:__down_write_common kernel/locking/rwsem.c:1316 [inline]
RIP: 0010:__down_write kernel/locking/rwsem.c:1326 [inline]
RIP: 0010:down_write+0xd1/0x1f0 kernel/locking/rwsem.c:1591
Code: 24 20 00 00 00 00 48 89 df be 08 00 00 00 e8 06 1b dd f6 4c 89 f7 be 08 00 00 00 e8 f9 1a dd f6 48 8b 44 24 20 b9 01 00 00 00 <f0> 48 0f b1 0b 0f 85 c2 00 00 00 48 c7 c0 90 0b 9e 8f 48 c1 e8 03
RSP: 0018:ffffc9000bc379a0 EFLAGS: 00010256
RAX: 0000000000000000 RBX: ffffffff8b04ae58 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9000bc379c0
RBP: ffffc9000bc37a28 R08: ffffc9000bc379c7 R09: 1ffff92001786f38
R10: dffffc0000000000 R11: fffff52001786f39 R12: 1ffff92001786f34
R13: dffffc0000000000 R14: ffffc9000bc379c0 R15: dffffc0000000000
FS: 00007f95249cd6c0(0000) GS:ffff888125e1f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffff8b04ae58 CR3: 0000000078bb2000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 24 20 and $0x20,%al
2: 00 00 add %al,(%rax)
4: 00 00 add %al,(%rax)
6: 48 89 df mov %rbx,%rdi
9: be 08 00 00 00 mov $0x8,%esi
e: e8 06 1b dd f6 call 0xf6dd1b19
13: 4c 89 f7 mov %r14,%rdi
16: be 08 00 00 00 mov $0x8,%esi
1b: e8 f9 1a dd f6 call 0xf6dd1b19
20: 48 8b 44 24 20 mov 0x20(%rsp),%rax
25: b9 01 00 00 00 mov $0x1,%ecx
* 2a: f0 48 0f b1 0b lock cmpxchg %rcx,(%rbx) <-- trapping instruction
2f: 0f 85 c2 00 00 00 jne 0xf7
35: 48 c7 c0 90 0b 9e 8f mov $0xffffffff8f9e0b90,%rax
3c: 48 c1 e8 03 shr $0x3,%rax
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
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