* [syzbot] [kernel?] BUG: sleeping function called from invalid context in posix_cpu_timer_wait_running
@ 2026-08-24 5:14 syzbot
0 siblings, 0 replies; only message in thread
From: syzbot @ 2026-08-24 5:14 UTC (permalink / raw)
To: anna-maria, frederic, linux-kernel, syzkaller-bugs, tglx
Hello,
syzbot found the following issue on:
HEAD commit: 2709dd5ae32f Merge tag 'sched-urgent-2026-08-22' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15c5d549580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a70bec3546180b6
dashboard link: https://syzkaller.appspot.com/bug?extid=143e0859898751aa8f94
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13c5d549580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fbfb2a76c4a3/disk-2709dd5a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3e8e5eeead5a/vmlinux-2709dd5a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/644acb46eb2b/bzImage-2709dd5a.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+143e0859898751aa8f94@syzkaller.appspotmail.com
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:623
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 5880, name: syz.0.17
preempt_count: 10000, expected: 0
RCU nest depth: 0, expected: 0
locks held by syz.0.17/5880: 0, last CPU#0
Preemption disabled at:
[<ffffffff818b3c57>] percpu_up_read include/linux/percpu-rwsem.h:116 [inline]
[<ffffffff818b3c57>] cgroup_threadgroup_change_end+0x87/0x210 include/linux/cgroup-defs.h:905
CPU: 0 UID: 0 PID: 5880 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
__might_resched+0x36a/0x4c0 kernel/sched/core.c:9234
__mutex_lock_common kernel/locking/mutex.c:623 [inline]
__mutex_lock+0x118/0x1550 kernel/locking/mutex.c:821
posix_cpu_timer_wait_running+0x1d3/0x330 kernel/time/posix-cpu-timers.c:1218
timer_wait_running kernel/time/posix-timers.c:868 [inline]
posix_timer_delete+0x349/0x490 kernel/time/posix-timers.c:1061
exit_itimers+0x1eb/0x3a0 kernel/time/posix-timers.c:1104
do_exit+0x489/0x2360 kernel/exit.c:967
do_group_exit+0x22d/0x2f0 kernel/exit.c:1151
get_signal+0x121b/0x12c0 kernel/signal.c:3046
arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
__do_fast_syscall_32+0x437/0x6a0 arch/x86/entry/syscall_32.c:294
do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:316
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf70af0ec
Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
RSP: 002b:00000000f68845bc EFLAGS: 00000206 ORIG_RAX: 00000000000000f0
RAX: fffffffffffffe00 RBX: 00000000f74a5020 RCX: 0000000000000080
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000f74a5024
RBP: 0000000000000081 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
Code disassembly (best guess):
0: 90 nop
1: 85 d2 test %edx,%edx
3: 74 0a je 0xf
5: 89 ce mov %ecx,%esi
7: 81 e6 ff 0f 00 00 and $0xfff,%esi
d: 89 32 mov %esi,(%rdx)
f: 85 c0 test %eax,%eax
11: 74 05 je 0x18
13: c1 e9 0c shr $0xc,%ecx
16: 89 08 mov %ecx,(%rax)
18: 31 c0 xor %eax,%eax
1a: 5e pop %rsi
1b: 5d pop %rbp
1c: c3 ret
1d: 90 nop
1e: 0f 1f 00 nopl (%rax)
21: 51 push %rcx
22: 52 push %rdx
23: 55 push %rbp
24: 89 e5 mov %esp,%ebp
26: 0f 34 sysenter
28: cd 80 int $0x80
* 2a: 5d pop %rbp <-- trapping instruction
2b: 5a pop %rdx
2c: 59 pop %rcx
2d: c3 ret
2e: 90 nop
2f: 90 nop
30: 90 nop
31: 90 nop
32: 90 nop
33: 90 nop
34: 90 nop
35: 90 nop
36: 90 nop
37: 90 nop
38: 90 nop
39: 90 nop
3a: 90 nop
3b: 90 nop
3c: 90 nop
3d: 90 nop
3e: 58 pop %rax
3f: b8 .byte 0xb8
---
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2026-08-24 5:14 [syzbot] [kernel?] BUG: sleeping function called from invalid context in posix_cpu_timer_wait_running syzbot
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