syzbot


WARNING in hrtimer_forward (4)

Status: upstream: reported on 2025/08/30 02:00
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+8b3a2e23253b50098164@syzkaller.appspotmail.com
First crash: 51d, last: 23d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] WARNING in hrtimer_forward (4) 2 (3) 2025/09/11 09:15
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in hrtimer_forward kernel -1 C done done 217 1362d 1847d 20/29 fixed on 2022/03/08 16:11
upstream WARNING in hrtimer_forward (2) kernel -1 1 559d 555d 0/29 auto-obsoleted due to no activity on 2024/07/14 02:37
upstream WARNING in hrtimer_forward (3) kernel -1 3 343d 437d 28/29 fixed on 2024/12/16 09:50

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 0 at kernel/time/hrtimer.c:1052 hrtimer_forward+0x1d6/0x2b0 kernel/time/hrtimer.c:1052
Modules linked in:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:hrtimer_forward+0x1d6/0x2b0 kernel/time/hrtimer.c:1052
Code: 4c 89 33 48 8b 04 24 eb 07 e8 66 34 12 00 31 c0 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 4b 34 12 00 90 <0f> 0b 90 eb df 48 89 e8 4c 09 f8 48 c1 e8 20 74 0a 48 89 e8 31 d2
RSP: 0018:ffffc90000a78bd0 EFLAGS: 00010006
RAX: ffffffff81ac39f5 RBX: ffff8880b883b508 RCX: ffff88801c69d940
RDX: 0000000000000000 RSI: 0000000000010000 RDI: 0000000000010000
RBP: 00000000000692fb R08: 0000000000010000 R09: 0000000000010000
R10: dffffc0000000000 R11: ffffffff8167a830 R12: ffff8880b883b520
R13: 000000003891623b R14: 1ffff110171076a4 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881269bc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5475e30c6a CR3: 0000000059c32000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 hrtimer_forward_now include/linux/hrtimer.h:366 [inline]
 dl_server_timer kernel/sched/deadline.c:1193 [inline]
 dl_task_timer+0xa42/0x12d0 kernel/sched/deadline.c:1234
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x503/0xd40 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x45d/0xa90 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: 13 b3 03 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 13 26 11 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc900001d7de0 EFLAGS: 000002c6
RAX: 6c65ac82b07bd600 RBX: ffffffff81955f48 RCX: 6c65ac82b07bd600
RDX: 0000000000000001 RSI: ffffffff8d03ad5b RDI: ffffffff8b621680
RBP: ffffc900001d7f20 R08: ffff8880b893341b R09: 1ffff11017126683
R10: dffffc0000000000 R11: ffffed1017126684 R12: ffffffff8f1d6230
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff110038d3b28
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:757
 default_idle_call+0x74/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0x1e8/0x510 kernel/sched/idle.c:330
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428
 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:315
 common_startup_64+0x13e/0x147
 </TASK>
----------------
Code disassembly (best guess):
   0:	13 b3 03 00 cc cc    	adc    -0x3333fffd(%rbx),%esi
   6:	cc                   	int3
   7:	90                   	nop
   8:	90                   	nop
   9:	90                   	nop
   a:	90                   	nop
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
  16:	90                   	nop
  17:	f3 0f 1e fa          	endbr64
  1b:	66 90                	xchg   %ax,%ax
  1d:	0f 00 2d 13 26 11 00 	verw   0x112613(%rip)        # 0x112637
  24:	f3 0f 1e fa          	endbr64
  28:	fb                   	sti
  29:	f4                   	hlt
* 2a:	c3                   	ret <-- trapping instruction
  2b:	cc                   	int3
  2c:	cc                   	int3
  2d:	cc                   	int3
  2e:	cc                   	int3
  2f:	cc                   	int3
  30:	cc                   	int3
  31:	cc                   	int3
  32:	cc                   	int3
  33:	cc                   	int3
  34:	cc                   	int3
  35:	cc                   	int3
  36:	cc                   	int3
  37:	90                   	nop
  38:	90                   	nop
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/22 17:28 upstream 07e27ad16399 0ac7291c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in hrtimer_forward
2025/09/13 10:56 upstream 22f20375f5b7 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in hrtimer_forward
2025/08/26 01:48 upstream b6add54ba618 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in hrtimer_forward
* Struck through repros no longer work on HEAD.