syzbot


upstream test error: WARNING in call_timer_fn

Status: upstream: reported on 2026/06/06 19:06
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+8b331cede7bfea7c674c@syzkaller.appspotmail.com
First crash: 4d07h, last: 4d07h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [mm?] upstream test error: WARNING in call_timer_fn 1 (2) 2026/06/06 20:06

Sample crash report:
------------[ cut here ]------------
workqueue: cannot queue hci_cmd_timeout on wq hci0
WARNING: kernel/workqueue.c:2298 at __queue_work+0xd3f/0x1040 kernel/workqueue.c:2296, CPU#0: syz-executor/5425
Modules linked in:
CPU: 0 UID: 0 PID: 5425 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__queue_work+0xd67/0x1040 kernel/workqueue.c:2296
Code: a6 0e 49 8d 7d 18 48 89 f8 48 c1 e8 03 42 80 3c 20 00 74 05 e8 7a 7b a5 00 49 8b 75 18 49 81 c7 70 01 00 00 4c 89 f7 4c 89 fa <67> 48 0f b9 3a 4c 89 e8 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 ef
RSP: 0000:ffffc90000007bd8 EFLAGS: 00010082
RAX: 1ffff1100259b94e RBX: 0000000000000008 RCX: ffff8880336a2540
RDX: ffff888041425170 RSI: ffffffff8a9c7e10 RDI: ffffffff90334eb0
RBP: 0000000000000100 R08: ffffffff90304ff7 R09: 1ffffffff20609fe
R10: dffffc0000000000 R11: ffffffff818d37e0 R12: dffffc0000000000
R13: ffff888012cdca58 R14: ffffffff90334eb0 R15: ffff888041425170
FS:  0000000000000000(0000) GS:ffff88808c891000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2fa63fff CR3: 0000000012c0c000 CR4: 0000000000352ef0
Call Trace:
 <IRQ>
 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1794 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x67e/0x8b0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
 handle_softirqs+0x22a/0x840 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:97 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:115 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:140 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:172 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:191 [inline]
RIP: 0010:kasan_check_range+0x90/0x2c0 mm/kasan/generic.c:200
Code: 03 48 bb 01 00 00 00 00 fc ff df 4d 8d 34 19 4d 89 f4 4d 29 dc 49 83 fc 10 7f 29 4d 85 e4 0f 84 3d 01 00 00 4c 89 cb 48 f7 d3 <4c> 01 fb 41 80 3b 00 0f 85 9e 01 00 00 49 ff c3 48 ff c3 75 ee e9
RSP: 0000:ffffc9000e2bf240 EFLAGS: 00000202
RAX: 1ffff92001c57e01 RBX: e00006dffe3a8187 RCX: ffffffff8176f0e3
RDX: 0000000000000001 RSI: 0000000000000010 RDI: ffffc9000e2bf3b8
RBP: 0000000000000000 R08: ffffc9000e2bf3c7 R09: 1ffff92001c57e78
R10: dffffc0000000000 R11: fffff52001c57e77 R12: 0000000000000002
R13: 1ffff92001c57e6f R14: fffff52001c57e79 R15: 1ffff92001c57e77
 __asan_memset+0x22/0x50 mm/kasan/shadow.c:84
 unwind_next_frame+0xf33/0x2550 arch/x86/kernel/unwind_orc.c:621
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3131 [inline]
 call_rcu+0xee/0x890 kernel/rcu/tree.c:3251
 slab_free_hook mm/slub.c:2653 [inline]
 slab_free mm/slub.c:6251 [inline]
 kmem_cache_free+0x462/0x650 mm/slub.c:6378
 tear_down_vmas+0x312/0x520 mm/mmap.c:1262
 exit_mmap+0x4b6/0x9e0 mm/mmap.c:1320
 __mmput+0x118/0x430 kernel/fork.c:1178
 exit_mm+0x1f6/0x2d0 kernel/exit.c:582
 do_exit+0x6a2/0x22c0 kernel/exit.c:964
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1119
 get_signal+0x1284/0x1330 kernel/signal.c:3037
 arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0xa9/0x680 kernel/entry/common.c:98
 __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:318 [inline]
 do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f328ef57fd7
Code: Unable to access opcode bytes at 0x7f328ef57fad.
RSP: 002b:00007ffd7ad34110 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 0000555594d02500 RCX: 00007f328ef57fd7
RDX: 0000000040000000 RSI: 00007ffd7ad3416c RDI: ffffffffffffffff
RBP: 00007ffd7ad3416c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffd7ad341e8
R13: 0000000000000002 R14: 00007ffd7ad343c8 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	49 8d 7d 18          	lea    0x18(%r13),%rdi
   4:	48 89 f8             	mov    %rdi,%rax
   7:	48 c1 e8 03          	shr    $0x3,%rax
   b:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
  10:	74 05                	je     0x17
  12:	e8 7a 7b a5 00       	call   0xa57b91
  17:	49 8b 75 18          	mov    0x18(%r13),%rsi
  1b:	49 81 c7 70 01 00 00 	add    $0x170,%r15
  22:	4c 89 f7             	mov    %r14,%rdi
  25:	4c 89 fa             	mov    %r15,%rdx
* 28:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2d:	4c 89 e8             	mov    %r13,%rax
  30:	48 c1 e8 03          	shr    $0x3,%rax
  34:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
  39:	74 08                	je     0x43
  3b:	4c 89 ef             	mov    %r13,%rdi

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/02 18:55 upstream ba3e43a9e601 62fe1528 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root upstream test error: WARNING in call_timer_fn
* Struck through repros no longer work on HEAD.