syzbot
possible deadlock in lock_system_sleep (2)
Status:
upstream: reported C repro on 2026/10/19 18:08
Labels:
prio:low
[Documentation on labels]
Reported-by: syzbot+1f0fbc2561b3e5d51b91@syzkaller.appspotmail.com
First crash: 1d20h, last: 1d20h
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Last patch testing requests (1)
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Cause bisection attempts (1)
Sample crash report:
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.3.5755/5950 is trying to acquire lock:
ffffffff8fc04760 (system_transition_mutex){+.+.}-{4:4}, at: lock_system_sleep+0x49/0x70 kernel/power/main.c:71
but task is already holding lock:
ffffffff8fc04760 (system_transition_mutex){+.+.}-{4:4}, at: __do_sys_reboot kernel/reboot.c:774 [inline]
ffffffff8fc04760 (system_transition_mutex){+.+.}-{4:4}, at: __se_sys_reboot+0x223/0x460 kernel/reboot.c:738
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(system_transition_mutex);
lock(system_transition_mutex);
*** DEADLOCK ***
May be due to missing lock nesting notation
locks held by syz.3.5755/5950: 1, last CPU#0:
#0: ffffffff8fc04760 (system_transition_mutex){+.+.}-{4:4}, at: __do_sys_reboot kernel/reboot.c:774 [inline]
#0: ffffffff8fc04760 (system_transition_mutex){+.+.}-{4:4}, at: __se_sys_reboot+0x223/0x460 kernel/reboot.c:738
stack backtrace:
CPU: 0 UID: 0 PID: 5950 Comm: syz.3.5755 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_deadlock_bug+0x27a/0x290 kernel/locking/lockdep.c:3085
check_deadlock kernel/locking/lockdep.c:3137 [inline]
validate_chain kernel/locking/lockdep.c:3939 [inline]
__lock_acquire+0x25db/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+0x19d/0x1550 kernel/locking/mutex.c:821
lock_system_sleep+0x49/0x70 kernel/power/main.c:71
hibernate+0x162/0x680 kernel/power/hibernate.c:784
__do_sys_reboot kernel/reboot.c:816 [inline]
__se_sys_reboot+0x2ba/0x460 kernel/reboot.c:738
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: 0033:0x7fdb2419f809
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffff22cee98 EFLAGS: 00000246 ORIG_RAX: 00000000000000a9
RAX: ffffffffffffffda RBX: 00007ffff22cefc8 RCX: 00007fdb2419f809
RDX: 00000000d000fce2 RSI: 0000000028121969 RDI: 00000000fee1dead
RBP: 0000000000000001 R08: 0000000000000000 R09: 00007ffff22cefc8
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffff22cefb8
R13: 0000000000000002 R14: 00007fdb24222cc0 R15: 0000000000000002
</TASK>
* Struck through repros no longer work on HEAD.