* [syzbot] [kernel?] INFO: rcu detected stall in __hrtimer_run_queues (3)
@ 2026-08-08 20:09 syzbot
2026-08-31 15:55 ` syzbot
0 siblings, 1 reply; 4+ messages in thread
From: syzbot @ 2026-08-08 20:09 UTC (permalink / raw)
To: anna-maria, frederic, linux-kernel, netdev, syzkaller-bugs, tglx
Hello,
syzbot found the following issue on:
HEAD commit: 594d90519502 af_unix: Unlink scc_entry in unix_del_edge().
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=13d4c132580000
kernel config: https://syzkaller.appspot.com/x/.config?x=3e8a402093abe6b2
dashboard link: https://syzkaller.appspot.com/bug?extid=6d991f16f4bcc8eeea24
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17d4c132580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/672b53d154af/disk-594d9051.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6f5c69520cde/vmlinux-594d9051.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5f0629640136/bzImage-594d9051.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6d991f16f4bcc8eeea24@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5762
rcu: (detected by 0, t=10502 jiffies, g=15917, q=4592 ncpus=2)
task:syz-executor state:R running task stack:22408 pid:5762 tgid:5762 ppid:1 task_flags:0x400140 flags:0x00080012
Call Trace:
<IRQ>
sched_show_task+0x4aa/0x5f0 kernel/sched/core.c:8184
rcu_print_detail_task_stall_rnp kernel/rcu/tree_stall.h:292 [inline]
print_other_cpu_stall+0xf7d/0x1310 kernel/rcu/tree_stall.h:680
check_cpu_stall kernel/rcu/tree_stall.h:855 [inline]
rcu_pending kernel/rcu/tree.c:3708 [inline]
rcu_sched_clock_irq+0x93d/0x1050 kernel/rcu/tree.c:2744
update_process_times+0x23b/0x2f0 kernel/time/timer.c:2475
tick_sched_handle kernel/time/tick-sched.c:296 [inline]
tick_nohz_handler+0x38f/0x6b0 kernel/time/tick-sched.c:317
__run_hrtimer kernel/time/hrtimer.c:2032 [inline]
__hrtimer_run_queues+0x371/0xa10 kernel/time/hrtimer.c:2096
hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
__sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:198
Code: f7 e8 2d 7d d0 f5 f7 c3 00 02 00 00 74 05 e8 00 5e fc f5 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> c4 90 c1 f5 65 8b 05 bd a0 99 07 85 c0 74 18 5b 41 5e c3 cc cc
RSP: 0018:ffffc90000007e08 EFLAGS: 00000206
RAX: 0000000000000002 RBX: 0000000000000246 RCX: 0000000000000102
RDX: 0000000000000000 RSI: ffffffff8e227e64 RDI: 0000000000000001
RBP: ffff88807b4d0938 R08: ffffffff90573637 R09: 1ffffffff20ae6c6
R10: dffffc0000000000 R11: fffffbfff20ae6c7 R12: ffff8880b86281c0
R13: ffffffff89cd5bf0 R14: ffff8880b86281c0 R15: 1ffff110170c50c2
__run_hrtimer kernel/time/hrtimer.c:2028 [inline]
__hrtimer_run_queues+0x2bf/0xa10 kernel/time/hrtimer.c:2096
hrtimer_run_softirq+0x17a/0x240 kernel/time/hrtimer.c:2113
handle_softirqs+0x225/0x840 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:1062 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:finish_task_switch+0x417/0xc60 kernel/sched/core.c:5361
Code: 04 00 00 41 c7 84 24 20 0e 00 00 00 00 00 00 0f 1f 44 00 00 49 83 c4 48 4c 89 e7 e8 53 4c 3d 0a e8 de aa 39 00 fb 4c 8b 65 c8 <49> 8d bc 24 f8 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0
RSP: 0018:ffffc900031ef320 EFLAGS: 00000206
RAX: 0000000000018aa5 RBX: ffff8880b863bf20 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8e227e64 RDI: ffffffff8c4bba80
RBP: ffffc900031ef370 R08: ffffffff90573637 R09: 1ffffffff20ae6c6
R10: dffffc0000000000 R11: fffffbfff20ae6c7 R12: ffff888029f49f00
R13: ffff8880b863bee8 R14: dffffc0000000000 R15: 1ffff110170c77e4
context_switch kernel/sched/core.c:5513 [inline]
__schedule+0x17e1/0x56c0 kernel/sched/core.c:7234
preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 51 6d 2d 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 db c7 c9 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 80 6f 30 0a cc 48 8d 3d c8 0c b8
RSP: 0018:ffffc900031ef6a0 EFLAGS: 00000286
RAX: fa5918e404740300 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 000000005a44979c RSI: ffffffff8e4acd09 RDI: ffffffff8c4bba80
RBP: ffffffff8177827f R08: ffffffff8177827f R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 0000000000000002
R13: ffffffff8eb59c60 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
rcu_read_lock include/linux/rcupdate.h:840 [inline]
class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
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:3159 [inline]
call_rcu+0xee/0x8b0 kernel/rcu/tree.c:3279
__destroy_inode+0x2a1/0x630 fs/inode.c:362
destroy_inode fs/inode.c:385 [inline]
evict+0x8d4/0xb50 fs/inode.c:849
dentry_kill+0x1b9/0x880 fs/dcache.c:826
finish_dput+0x1a/0x260 fs/dcache.c:1001
__fput+0x675/0xa50 fs/file_table.c:520
fput_close_sync+0x11f/0x240 fs/file_table.c:617
__do_sys_close fs/open.c:1511 [inline]
__se_sys_close fs/open.c:1496 [inline]
__x64_sys_close+0x7e/0x110 fs/open.c:1496
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6c4799d247
Code: 44 00 00 48 83 ec 10 48 63 ff 45 31 c9 45 31 c0 6a 01 31 c9 e8 3a c0 fb ff 48 83 c4 18 c3 0f 1f 44 00 00 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffdab7221d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007f6c4799d247
RDX: 0000000000000000 RSI: 0000000000008933 RDI: 0000000000000005
RBP: 0000000000000003 R08: 0000000000000000 R09: 00000000fffffff9
R10: 0000000000000002 R11: 0000000000000246 R12: 00007ffdab722260
R13: 00007ffdab722350 R14: 00007f6c48754620 R15: 00007ffdab722350
</TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10546 jiffies! g15917 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=0 timer-softirq=3578
rcu: rcu_preempt kthread starved for 10577 jiffies! g15917 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:I stack:27752 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7326
schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5762 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:198
Code: f7 e8 2d 7d d0 f5 f7 c3 00 02 00 00 74 05 e8 00 5e fc f5 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> c4 90 c1 f5 65 8b 05 bd a0 99 07 85 c0 74 18 5b 41 5e c3 cc cc
RSP: 0018:ffffc90000007e08 EFLAGS: 00000206
RAX: 0000000000000002 RBX: 0000000000000246 RCX: 0000000000000102
RDX: 0000000000000000 RSI: ffffffff8e227e64 RDI: 0000000000000001
RBP: ffff88807b4d0938 R08: ffffffff90573637 R09: 1ffffffff20ae6c6
R10: dffffc0000000000 R11: fffffbfff20ae6c7 R12: ffff8880b86281c0
R13: ffffffff89cd5bf0 R14: ffff8880b86281c0 R15: 1ffff110170c50c2
FS: 000055555c50f500(0000) GS:ffff888124f58000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cf03528bd0 CR3: 000000007fb92000 CR4: 00000000003526f0
Call Trace:
<IRQ>
__run_hrtimer kernel/time/hrtimer.c:2028 [inline]
__hrtimer_run_queues+0x2bf/0xa10 kernel/time/hrtimer.c:2096
hrtimer_run_softirq+0x17a/0x240 kernel/time/hrtimer.c:2113
handle_softirqs+0x225/0x840 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:1062 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:finish_task_switch+0x417/0xc60 kernel/sched/core.c:5361
Code: 04 00 00 41 c7 84 24 20 0e 00 00 00 00 00 00 0f 1f 44 00 00 49 83 c4 48 4c 89 e7 e8 53 4c 3d 0a e8 de aa 39 00 fb 4c 8b 65 c8 <49> 8d bc 24 f8 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0
RSP: 0018:ffffc900031ef320 EFLAGS: 00000206
RAX: 0000000000018aa5 RBX: ffff8880b863bf20 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8e227e64 RDI: ffffffff8c4bba80
RBP: ffffc900031ef370 R08: ffffffff90573637 R09: 1ffffffff20ae6c6
R10: dffffc0000000000 R11: fffffbfff20ae6c7 R12: ffff888029f49f00
R13: ffff8880b863bee8 R14: dffffc0000000000 R15: 1ffff110170c77e4
context_switch kernel/sched/core.c:5513 [inline]
__schedule+0x17e1/0x56c0 kernel/sched/core.c:7234
preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 51 6d 2d 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 db c7 c9 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 80 6f 30 0a cc 48 8d 3d c8 0c b8
RSP: 0018:ffffc900031ef6a0 EFLAGS: 00000286
RAX: fa5918e404740300 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 000000005a44979c RSI: ffffffff8e4acd09 RDI: ffffffff8c4bba80
RBP: ffffffff8177827f R08: ffffffff8177827f R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 0000000000000002
R13: ffffffff8eb59c60 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
rcu_read_lock include/linux/rcupdate.h:840 [inline]
class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
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:3159 [inline]
call_rcu+0xee/0x8b0 kernel/rcu/tree.c:3279
__destroy_inode+0x2a1/0x630 fs/inode.c:362
destroy_inode fs/inode.c:385 [inline]
evict+0x8d4/0xb50 fs/inode.c:849
dentry_kill+0x1b9/0x880 fs/dcache.c:826
finish_dput+0x1a/0x260 fs/dcache.c:1001
__fput+0x675/0xa50 fs/file_table.c:520
fput_close_sync+0x11f/0x240 fs/file_table.c:617
__do_sys_close fs/open.c:1511 [inline]
__se_sys_close fs/open.c:1496 [inline]
__x64_sys_close+0x7e/0x110 fs/open.c:1496
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6c4799d247
Code: 44 00 00 48 83 ec 10 48 63 ff 45 31 c9 45 31 c0 6a 01 31 c9 e8 3a c0 fb ff 48 83 c4 18 c3 0f 1f 44 00 00 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffdab7221d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007f6c4799d247
RDX: 0000000000000000 RSI: 0000000000008933 RDI: 0000000000000005
RBP: 0000000000000003 R08: 0000000000000000 R09: 00000000fffffff9
R10: 0000000000000002 R11: 0000000000000246 R12: 00007ffdab722260
R13: 00007ffdab722350 R14: 00007f6c48754620 R15: 00007ffdab722350
</TASK>
sched: DL replenish lagged too much
---
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If the report is already addressed, let syzbot know by replying with:
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If you want syzbot to run the reproducer, reply with:
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [kernel?] INFO: rcu detected stall in __hrtimer_run_queues (3)
2026-08-08 20:09 [syzbot] [kernel?] INFO: rcu detected stall in __hrtimer_run_queues (3) syzbot
@ 2026-08-31 15:55 ` syzbot
2026-09-04 5:00 ` Thomas Gleixner
0 siblings, 1 reply; 4+ messages in thread
From: syzbot @ 2026-08-31 15:55 UTC (permalink / raw)
To: anna-maria, frederic, linux-kernel, netdev, syzkaller-bugs, tglx
syzbot has found a reproducer for the following issue on:
HEAD commit: f1b8fa82cab7 Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=15aee379580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d1128bc53f2ef7f3
dashboard link: https://syzkaller.appspot.com/bug?extid=6d991f16f4bcc8eeea24
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15632d9e580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15dd1c15580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/932d85a2bda2/disk-f1b8fa82.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5b6b8fb76e8d/vmlinux-f1b8fa82.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c246b61ee396/Image-f1b8fa82.gz.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6d991f16f4bcc8eeea24@syzkaller.appspotmail.com
watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [syz-executor:4831]
Modules linked in:
irq event stamp: 38640849
hardirqs last enabled at (38640848): [<ffff800080557cd8>] seqcount_lockdep_reader_access+0x7c/0xf8 include/linux/seqlock.h:75
hardirqs last disabled at (38640849): [<ffff80008690cd0c>] __el1_irq arch/arm64/kernel/entry-common.c:527 [inline]
hardirqs last disabled at (38640849): [<ffff80008690cd0c>] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:543
softirqs last enabled at (147672): [<ffff80008013891c>] local_bh_enable include/linux/bottom_half.h:33 [inline]
softirqs last enabled at (147672): [<ffff80008013891c>] put_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:251 [inline]
softirqs last enabled at (147672): [<ffff80008013891c>] do_sve_acc+0x32c/0x4b8 arch/arm64/kernel/fpsimd.c:1349
softirqs last disabled at (148217): [<ffff8000800204c0>] __do_softirq+0x14/0x20 kernel/softirq.c:656
CPU: 0 UID: 0 PID: 4831 Comm: syz-executor Not tainted syzkaller #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
pstate: 43400005 (nZcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline]
pc : __run_hrtimer kernel/time/hrtimer.c:2035 [inline]
pc : __hrtimer_run_queues+0x32c/0xbe0 kernel/time/hrtimer.c:2096
lr : arch_static_branch arch/arm64/include/asm/jump_label.h:36 [inline]
lr : trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline]
lr : __run_hrtimer kernel/time/hrtimer.c:2035 [inline]
lr : __hrtimer_run_queues+0x32c/0xbe0 kernel/time/hrtimer.c:2096
sp : ffff80008eb67de0
x29: ffff80008eb67e40 x28: 1fffe00034bb7c3a x27: ffff0001a5dbe1c0
x26: ffff0000c6453a90 x25: ffff0000d1a50d38 x24: dfff800000000000
x23: 0000000000000001 x22: ffff800084ec6bd4 x21: 1fffe00018c8a752
x20: ffff0000c64545a8 x19: ffff0000c6453a80 x18: 0000000000000000
x17: ffff80011d2d8000 x16: ffff80008eb60000 x15: 0000000000000000
x14: 00000000ffff8000 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000102 x9 : 0000000000000101
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff80008046a634
x2 : 0000000000000001 x1 : ffff0000c6453a80 x0 : 0000000000000000
Call trace:
arch_static_branch arch/arm64/include/asm/jump_label.h:36 [inline] (P)
trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline] (P)
__run_hrtimer kernel/time/hrtimer.c:2035 [inline] (P)
__hrtimer_run_queues+0x32c/0xbe0 kernel/time/hrtimer.c:2096 (P)
hrtimer_run_softirq+0x15c/0x21c kernel/time/hrtimer.c:2113
handle_softirqs+0x2ec/0xd98 kernel/softirq.c:622
__do_softirq+0x14/0x20 kernel/softirq.c:656
____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:78
call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:885
do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:83
invoke_softirq kernel/softirq.c:503 [inline]
__irq_exit_rcu+0x1ac/0x428 kernel/softirq.c:735
irq_exit_rcu+0x14/0x84 kernel/softirq.c:752
__el1_irq arch/arm64/kernel/entry-common.c:531 [inline]
el1_interrupt+0x40/0x60 arch/arm64/kernel/entry-common.c:543
el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:548
el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:586
__daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline] (P)
_raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:198 (P)
__debug_check_no_obj_freed lib/debugobjects.c:1180 [inline]
debug_check_no_obj_freed+0x2c8/0x3a4 lib/debugobjects.c:1201
slab_free_hook mm/slub.c:2608 [inline]
slab_free mm/slub.c:6377 [inline]
kmem_cache_free+0x120/0x6b8 mm/slub.c:6504
file_free+0x128/0x1dc fs/file_table.c:104
__fput+0x538/0x74c fs/file_table.c:525
fput_close_sync+0x10c/0x278 fs/file_table.c:617
__do_sys_close fs/open.c:1511 [inline]
__se_sys_close fs/open.c:1496 [inline]
__arm64_sys_close+0x80/0x110 fs/open.c:1496
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 4802 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
Workqueue: rcu_gp process_srcu
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
pc : _raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:198
lr : __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline]
lr : _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:198
sp : ffff80008eb77dc0
x29: ffff80008eb77dc0 x28: 1fffe00034bbc63a x27: ffff0001a5de31c0
x26: ffff0001a5de31d0 x25: ffff0000d2a4a538 x24: dfff800000000000
x23: 0000000000000001 x22: ffff800084ec6bd4 x21: ffff0001a5de2d80
x20: ffff0001a5de2d80 x19: 0000000000000000 x18: 00000000ffffffff
x17: ffff80008a7d6000 x16: 0000000000000002 x15: ffff80008a35fda0
x14: ffff80008a5d5e28 x13: 0000000000000001 x12: 0000000000000000
x11: ffff80008a5d5e28 x10: 0000000000000003 x9 : 0000000000000000
x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff80008015611c
x2 : 0000000000000002 x1 : ffff0000d32c9d40 x0 : ffff80011d2fd000
Call trace:
__daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline] (P)
_raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:198 (P)
__run_hrtimer kernel/time/hrtimer.c:2028 [inline]
__hrtimer_run_queues+0x22c/0xbe0 kernel/time/hrtimer.c:2096
hrtimer_run_softirq+0x15c/0x21c kernel/time/hrtimer.c:2113
handle_softirqs+0x2ec/0xd98 kernel/softirq.c:622
__do_softirq+0x14/0x20 kernel/softirq.c:656
____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:78
call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:885
do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:83
invoke_softirq kernel/softirq.c:503 [inline]
__irq_exit_rcu+0x1ac/0x428 kernel/softirq.c:735
irq_exit_rcu+0x14/0x84 kernel/softirq.c:752
__el1_irq arch/arm64/kernel/entry-common.c:531 [inline]
el1_interrupt+0x40/0x60 arch/arm64/kernel/entry-common.c:543
el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:548
el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:586
__daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
queue_delayed_work_on+0xf4/0x140 kernel/workqueue.c:2624 (P)
queue_delayed_work include/linux/workqueue.h:714 [inline]
srcu_reschedule+0x240/0x338 kernel/rcu/srcutree.c:1957
process_srcu+0xd04/0x1eb8 kernel/rcu/srcutree.c:1991
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0x788/0x10b8 kernel/workqueue.c:3405
worker_thread+0x798/0xbd0 kernel/workqueue.c:3486
kthread+0x304/0x3d4 kernel/kthread.c:436
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
watchdog: BUG: soft lockup - CPU#1 stuck for 26s! [kworker/1:3:4802]
Modules linked in:
irq event stamp: 44430735
hardirqs last enabled at (44430734): [<ffff800086932074>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline]
hardirqs last enabled at (44430734): [<ffff800086932074>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:198
hardirqs last disabled at (44430735): [<ffff80008690cd0c>] __el1_irq arch/arm64/kernel/entry-common.c:527 [inline]
hardirqs last disabled at (44430735): [<ffff80008690cd0c>] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:543
softirqs last enabled at (6136): [<ffff80008030e6e4>] softirq_handle_end kernel/softirq.c:468 [inline]
softirqs last enabled at (6136): [<ffff80008030e6e4>] handle_softirqs+0xc28/0xd98 kernel/softirq.c:650
softirqs last disabled at (7461): [<ffff8000800204c0>] __do_softirq+0x14/0x20 kernel/softirq.c:656
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [kernel?] INFO: rcu detected stall in __hrtimer_run_queues (3)
2026-08-31 15:55 ` syzbot
@ 2026-09-04 5:00 ` Thomas Gleixner
2026-09-04 13:51 ` Aleksandr Nogikh
0 siblings, 1 reply; 4+ messages in thread
From: Thomas Gleixner @ 2026-09-04 5:00 UTC (permalink / raw)
To: syzbot, anna-maria, frederic, linux-kernel, netdev,
syzkaller-bugs
Cc: Catalin Marinas, Mark Rutland, Will Deacon
On Mon, Aug 31 2026 at 08:55, syzbot wrote:
CC+: ARM64 folks. It's their magic git tree ....
Maybe some day syzbot people get their act together and actually figure
out who should be CC'ed. Hope dies last...
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: f1b8fa82cab7 Merge branch 'for-next/core' into for-kernelci
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=15aee379580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=d1128bc53f2ef7f3
> dashboard link: https://syzkaller.appspot.com/bug?extid=6d991f16f4bcc8eeea24
> compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
> userspace arch: arm64
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15632d9e580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15dd1c15580000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/932d85a2bda2/disk-f1b8fa82.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/5b6b8fb76e8d/vmlinux-f1b8fa82.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/c246b61ee396/Image-f1b8fa82.gz.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+6d991f16f4bcc8eeea24@syzkaller.appspotmail.com
>
> watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [syz-executor:4831]
> Modules linked in:
> irq event stamp: 38640849
> hardirqs last enabled at (38640848): [<ffff800080557cd8>] seqcount_lockdep_reader_access+0x7c/0xf8 include/linux/seqlock.h:75
> hardirqs last disabled at (38640849): [<ffff80008690cd0c>] __el1_irq arch/arm64/kernel/entry-common.c:527 [inline]
> hardirqs last disabled at (38640849): [<ffff80008690cd0c>] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:543
> softirqs last enabled at (147672): [<ffff80008013891c>] local_bh_enable include/linux/bottom_half.h:33 [inline]
> softirqs last enabled at (147672): [<ffff80008013891c>] put_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:251 [inline]
> softirqs last enabled at (147672): [<ffff80008013891c>] do_sve_acc+0x32c/0x4b8 arch/arm64/kernel/fpsimd.c:1349
> softirqs last disabled at (148217): [<ffff8000800204c0>] __do_softirq+0x14/0x20 kernel/softirq.c:656
> CPU: 0 UID: 0 PID: 4831 Comm: syz-executor Not tainted syzkaller #0 PREEMPT
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
> pstate: 43400005 (nZcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
> pc : trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline]
> pc : __run_hrtimer kernel/time/hrtimer.c:2035 [inline]
> pc : __hrtimer_run_queues+0x32c/0xbe0 kernel/time/hrtimer.c:2096
> lr : arch_static_branch arch/arm64/include/asm/jump_label.h:36 [inline]
> lr : trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline]
> lr : __run_hrtimer kernel/time/hrtimer.c:2035 [inline]
> lr : __hrtimer_run_queues+0x32c/0xbe0 kernel/time/hrtimer.c:2096
> sp : ffff80008eb67de0
> x29: ffff80008eb67e40 x28: 1fffe00034bb7c3a x27: ffff0001a5dbe1c0
> x26: ffff0000c6453a90 x25: ffff0000d1a50d38 x24: dfff800000000000
> x23: 0000000000000001 x22: ffff800084ec6bd4 x21: 1fffe00018c8a752
> x20: ffff0000c64545a8 x19: ffff0000c6453a80 x18: 0000000000000000
> x17: ffff80011d2d8000 x16: ffff80008eb60000 x15: 0000000000000000
> x14: 00000000ffff8000 x13: 0000000000000001 x12: 0000000000000000
> x11: 0000000000000000 x10: 0000000000000102 x9 : 0000000000000101
> x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
> x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff80008046a634
> x2 : 0000000000000001 x1 : ffff0000c6453a80 x0 : 0000000000000000
> Call trace:
> arch_static_branch arch/arm64/include/asm/jump_label.h:36 [inline] (P)
> trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline] (P)
> __run_hrtimer kernel/time/hrtimer.c:2035 [inline] (P)
> __hrtimer_run_queues+0x32c/0xbe0 kernel/time/hrtimer.c:2096 (P)
> hrtimer_run_softirq+0x15c/0x21c kernel/time/hrtimer.c:2113
> handle_softirqs+0x2ec/0xd98 kernel/softirq.c:622
> __do_softirq+0x14/0x20 kernel/softirq.c:656
> ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:78
> call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:885
> do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:83
> invoke_softirq kernel/softirq.c:503 [inline]
> __irq_exit_rcu+0x1ac/0x428 kernel/softirq.c:735
> irq_exit_rcu+0x14/0x84 kernel/softirq.c:752
> __el1_irq arch/arm64/kernel/entry-common.c:531 [inline]
> el1_interrupt+0x40/0x60 arch/arm64/kernel/entry-common.c:543
> el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:548
> el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:586
> __daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
> arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
> __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline] (P)
> _raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:198 (P)
> __debug_check_no_obj_freed lib/debugobjects.c:1180 [inline]
> debug_check_no_obj_freed+0x2c8/0x3a4 lib/debugobjects.c:1201
> slab_free_hook mm/slub.c:2608 [inline]
> slab_free mm/slub.c:6377 [inline]
> kmem_cache_free+0x120/0x6b8 mm/slub.c:6504
> file_free+0x128/0x1dc fs/file_table.c:104
> __fput+0x538/0x74c fs/file_table.c:525
> fput_close_sync+0x10c/0x278 fs/file_table.c:617
> __do_sys_close fs/open.c:1511 [inline]
> __se_sys_close fs/open.c:1496 [inline]
> __arm64_sys_close+0x80/0x110 fs/open.c:1496
> __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
> invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
> el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
> do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
> el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
> el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
> el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
> Sending NMI from CPU 0 to CPUs 1:
> NMI backtrace for cpu 1
> CPU: 1 UID: 0 PID: 4802 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
> Workqueue: rcu_gp process_srcu
> pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
> pc : __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
> pc : _raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:198
> lr : __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline]
> lr : _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:198
> sp : ffff80008eb77dc0
> x29: ffff80008eb77dc0 x28: 1fffe00034bbc63a x27: ffff0001a5de31c0
> x26: ffff0001a5de31d0 x25: ffff0000d2a4a538 x24: dfff800000000000
> x23: 0000000000000001 x22: ffff800084ec6bd4 x21: ffff0001a5de2d80
> x20: ffff0001a5de2d80 x19: 0000000000000000 x18: 00000000ffffffff
> x17: ffff80008a7d6000 x16: 0000000000000002 x15: ffff80008a35fda0
> x14: ffff80008a5d5e28 x13: 0000000000000001 x12: 0000000000000000
> x11: ffff80008a5d5e28 x10: 0000000000000003 x9 : 0000000000000000
> x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000000
> x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff80008015611c
> x2 : 0000000000000002 x1 : ffff0000d32c9d40 x0 : ffff80011d2fd000
> Call trace:
> __daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
> arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
> __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline] (P)
> _raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:198 (P)
> __run_hrtimer kernel/time/hrtimer.c:2028 [inline]
> __hrtimer_run_queues+0x22c/0xbe0 kernel/time/hrtimer.c:2096
> hrtimer_run_softirq+0x15c/0x21c kernel/time/hrtimer.c:2113
> handle_softirqs+0x2ec/0xd98 kernel/softirq.c:622
> __do_softirq+0x14/0x20 kernel/softirq.c:656
> ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:78
> call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:885
> do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:83
> invoke_softirq kernel/softirq.c:503 [inline]
> __irq_exit_rcu+0x1ac/0x428 kernel/softirq.c:735
> irq_exit_rcu+0x14/0x84 kernel/softirq.c:752
> __el1_irq arch/arm64/kernel/entry-common.c:531 [inline]
> el1_interrupt+0x40/0x60 arch/arm64/kernel/entry-common.c:543
> el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:548
> el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:586
> __daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
> arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
> queue_delayed_work_on+0xf4/0x140 kernel/workqueue.c:2624 (P)
> queue_delayed_work include/linux/workqueue.h:714 [inline]
> srcu_reschedule+0x240/0x338 kernel/rcu/srcutree.c:1957
> process_srcu+0xd04/0x1eb8 kernel/rcu/srcutree.c:1991
> process_one_work kernel/workqueue.c:3322 [inline]
> process_scheduled_works+0x788/0x10b8 kernel/workqueue.c:3405
> worker_thread+0x798/0xbd0 kernel/workqueue.c:3486
> kthread+0x304/0x3d4 kernel/kthread.c:436
> ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
> watchdog: BUG: soft lockup - CPU#1 stuck for 26s! [kworker/1:3:4802]
> Modules linked in:
> irq event stamp: 44430735
> hardirqs last enabled at (44430734): [<ffff800086932074>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline]
> hardirqs last enabled at (44430734): [<ffff800086932074>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:198
> hardirqs last disabled at (44430735): [<ffff80008690cd0c>] __el1_irq arch/arm64/kernel/entry-common.c:527 [inline]
> hardirqs last disabled at (44430735): [<ffff80008690cd0c>] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:543
> softirqs last enabled at (6136): [<ffff80008030e6e4>] softirq_handle_end kernel/softirq.c:468 [inline]
> softirqs last enabled at (6136): [<ffff80008030e6e4>] handle_softirqs+0xc28/0xd98 kernel/softirq.c:650
> softirqs last disabled at (7461): [<ffff8000800204c0>] __do_softirq+0x14/0x20 kernel/softirq.c:656
>
>
> ---
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [kernel?] INFO: rcu detected stall in __hrtimer_run_queues (3)
2026-09-04 5:00 ` Thomas Gleixner
@ 2026-09-04 13:51 ` Aleksandr Nogikh
0 siblings, 0 replies; 4+ messages in thread
From: Aleksandr Nogikh @ 2026-09-04 13:51 UTC (permalink / raw)
To: Thomas Gleixner, Edward Adam Davis
Cc: syzbot, anna-maria, frederic, linux-kernel, netdev,
syzkaller-bugs, Catalin Marinas, Mark Rutland, Will Deacon,
syzkaller
On Fri, Sep 4, 2026 at 7:00 AM 'Thomas Gleixner' via syzkaller-bugs
<syzkaller-bugs@googlegroups.com> wrote:
>
> On Mon, Aug 31 2026 at 08:55, syzbot wrote:
>
> CC+: ARM64 folks. It's their magic git tree ....
>
> Maybe some day syzbot people get their act together and actually figure
> out who should be CC'ed. Hope dies last...
In this particular case, the fact that the reproducer ran against the
arm64 tree does not mean the bug is arm64-specific. As shown on the
dashboard (https://syzkaller.appspot.com/bug?extid=6d991f16f4bcc8eeea24),
most crashes are coming from the x86_64 instances.
Judging by what reproducers do, it seems to be related to
net/sched/act_gate.c's gate_timer_func(), for which a patch has
recently been posted by Edward Adam Davis (Cc'd):
https://lore.kernel.org/all/tencent_19FD76F366C43D4737EE9682371A4BF87409@qq.com/
Syzbot attributes reports to maintainers based on the crash stack
trace rather than the git tree URL. Because CPU lockups and stalls in
a looping timer callback were caught inside kernel/time/hrtimer.c,
get_maintainer.pl pointed it at the timer subsystem.
>
> > syzbot has found a reproducer for the following issue on:
> >
> > HEAD commit: f1b8fa82cab7 Merge branch 'for-next/core' into for-kernelci
> > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> > console output: https://syzkaller.appspot.com/x/log.txt?x=15aee379580000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=d1128bc53f2ef7f3
> > dashboard link: https://syzkaller.appspot.com/bug?extid=6d991f16f4bcc8eeea24
> > compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
> > userspace arch: arm64
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15632d9e580000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15dd1c15580000
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/932d85a2bda2/disk-f1b8fa82.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/5b6b8fb76e8d/vmlinux-f1b8fa82.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/c246b61ee396/Image-f1b8fa82.gz.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+6d991f16f4bcc8eeea24@syzkaller.appspotmail.com
> >
> > watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [syz-executor:4831]
> > Modules linked in:
> > irq event stamp: 38640849
> > hardirqs last enabled at (38640848): [<ffff800080557cd8>] seqcount_lockdep_reader_access+0x7c/0xf8 include/linux/seqlock.h:75
> > hardirqs last disabled at (38640849): [<ffff80008690cd0c>] __el1_irq arch/arm64/kernel/entry-common.c:527 [inline]
> > hardirqs last disabled at (38640849): [<ffff80008690cd0c>] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:543
> > softirqs last enabled at (147672): [<ffff80008013891c>] local_bh_enable include/linux/bottom_half.h:33 [inline]
> > softirqs last enabled at (147672): [<ffff80008013891c>] put_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:251 [inline]
> > softirqs last enabled at (147672): [<ffff80008013891c>] do_sve_acc+0x32c/0x4b8 arch/arm64/kernel/fpsimd.c:1349
> > softirqs last disabled at (148217): [<ffff8000800204c0>] __do_softirq+0x14/0x20 kernel/softirq.c:656
> > CPU: 0 UID: 0 PID: 4831 Comm: syz-executor Not tainted syzkaller #0 PREEMPT
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
> > pstate: 43400005 (nZcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
> > pc : trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline]
> > pc : __run_hrtimer kernel/time/hrtimer.c:2035 [inline]
> > pc : __hrtimer_run_queues+0x32c/0xbe0 kernel/time/hrtimer.c:2096
> > lr : arch_static_branch arch/arm64/include/asm/jump_label.h:36 [inline]
> > lr : trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline]
> > lr : __run_hrtimer kernel/time/hrtimer.c:2035 [inline]
> > lr : __hrtimer_run_queues+0x32c/0xbe0 kernel/time/hrtimer.c:2096
> > sp : ffff80008eb67de0
> > x29: ffff80008eb67e40 x28: 1fffe00034bb7c3a x27: ffff0001a5dbe1c0
> > x26: ffff0000c6453a90 x25: ffff0000d1a50d38 x24: dfff800000000000
> > x23: 0000000000000001 x22: ffff800084ec6bd4 x21: 1fffe00018c8a752
> > x20: ffff0000c64545a8 x19: ffff0000c6453a80 x18: 0000000000000000
> > x17: ffff80011d2d8000 x16: ffff80008eb60000 x15: 0000000000000000
> > x14: 00000000ffff8000 x13: 0000000000000001 x12: 0000000000000000
> > x11: 0000000000000000 x10: 0000000000000102 x9 : 0000000000000101
> > x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
> > x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff80008046a634
> > x2 : 0000000000000001 x1 : ffff0000c6453a80 x0 : 0000000000000000
> > Call trace:
> > arch_static_branch arch/arm64/include/asm/jump_label.h:36 [inline] (P)
> > trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline] (P)
> > __run_hrtimer kernel/time/hrtimer.c:2035 [inline] (P)
> > __hrtimer_run_queues+0x32c/0xbe0 kernel/time/hrtimer.c:2096 (P)
> > hrtimer_run_softirq+0x15c/0x21c kernel/time/hrtimer.c:2113
> > handle_softirqs+0x2ec/0xd98 kernel/softirq.c:622
> > __do_softirq+0x14/0x20 kernel/softirq.c:656
> > ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:78
> > call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:885
> > do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:83
> > invoke_softirq kernel/softirq.c:503 [inline]
> > __irq_exit_rcu+0x1ac/0x428 kernel/softirq.c:735
> > irq_exit_rcu+0x14/0x84 kernel/softirq.c:752
> > __el1_irq arch/arm64/kernel/entry-common.c:531 [inline]
> > el1_interrupt+0x40/0x60 arch/arm64/kernel/entry-common.c:543
> > el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:548
> > el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:586
> > __daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
> > arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
> > __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline] (P)
> > _raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:198 (P)
> > __debug_check_no_obj_freed lib/debugobjects.c:1180 [inline]
> > debug_check_no_obj_freed+0x2c8/0x3a4 lib/debugobjects.c:1201
> > slab_free_hook mm/slub.c:2608 [inline]
> > slab_free mm/slub.c:6377 [inline]
> > kmem_cache_free+0x120/0x6b8 mm/slub.c:6504
> > file_free+0x128/0x1dc fs/file_table.c:104
> > __fput+0x538/0x74c fs/file_table.c:525
> > fput_close_sync+0x10c/0x278 fs/file_table.c:617
> > __do_sys_close fs/open.c:1511 [inline]
> > __se_sys_close fs/open.c:1496 [inline]
> > __arm64_sys_close+0x80/0x110 fs/open.c:1496
> > __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
> > invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
> > el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
> > do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
> > el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
> > el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
> > el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
> > Sending NMI from CPU 0 to CPUs 1:
> > NMI backtrace for cpu 1
> > CPU: 1 UID: 0 PID: 4802 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
> > Workqueue: rcu_gp process_srcu
> > pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
> > pc : __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
> > pc : _raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:198
> > lr : __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline]
> > lr : _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:198
> > sp : ffff80008eb77dc0
> > x29: ffff80008eb77dc0 x28: 1fffe00034bbc63a x27: ffff0001a5de31c0
> > x26: ffff0001a5de31d0 x25: ffff0000d2a4a538 x24: dfff800000000000
> > x23: 0000000000000001 x22: ffff800084ec6bd4 x21: ffff0001a5de2d80
> > x20: ffff0001a5de2d80 x19: 0000000000000000 x18: 00000000ffffffff
> > x17: ffff80008a7d6000 x16: 0000000000000002 x15: ffff80008a35fda0
> > x14: ffff80008a5d5e28 x13: 0000000000000001 x12: 0000000000000000
> > x11: ffff80008a5d5e28 x10: 0000000000000003 x9 : 0000000000000000
> > x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000000
> > x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff80008015611c
> > x2 : 0000000000000002 x1 : ffff0000d32c9d40 x0 : ffff80011d2fd000
> > Call trace:
> > __daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
> > arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
> > __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline] (P)
> > _raw_spin_unlock_irqrestore+0x44/0x98 kernel/locking/spinlock.c:198 (P)
> > __run_hrtimer kernel/time/hrtimer.c:2028 [inline]
> > __hrtimer_run_queues+0x22c/0xbe0 kernel/time/hrtimer.c:2096
> > hrtimer_run_softirq+0x15c/0x21c kernel/time/hrtimer.c:2113
> > handle_softirqs+0x2ec/0xd98 kernel/softirq.c:622
> > __do_softirq+0x14/0x20 kernel/softirq.c:656
> > ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:78
> > call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:885
> > do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:83
> > invoke_softirq kernel/softirq.c:503 [inline]
> > __irq_exit_rcu+0x1ac/0x428 kernel/softirq.c:735
> > irq_exit_rcu+0x14/0x84 kernel/softirq.c:752
> > __el1_irq arch/arm64/kernel/entry-common.c:531 [inline]
> > el1_interrupt+0x40/0x60 arch/arm64/kernel/entry-common.c:543
> > el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:548
> > el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:586
> > __daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
> > arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
> > queue_delayed_work_on+0xf4/0x140 kernel/workqueue.c:2624 (P)
> > queue_delayed_work include/linux/workqueue.h:714 [inline]
> > srcu_reschedule+0x240/0x338 kernel/rcu/srcutree.c:1957
> > process_srcu+0xd04/0x1eb8 kernel/rcu/srcutree.c:1991
> > process_one_work kernel/workqueue.c:3322 [inline]
> > process_scheduled_works+0x788/0x10b8 kernel/workqueue.c:3405
> > worker_thread+0x798/0xbd0 kernel/workqueue.c:3486
> > kthread+0x304/0x3d4 kernel/kthread.c:436
> > ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
> > watchdog: BUG: soft lockup - CPU#1 stuck for 26s! [kworker/1:3:4802]
> > Modules linked in:
> > irq event stamp: 44430735
> > hardirqs last enabled at (44430734): [<ffff800086932074>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline]
> > hardirqs last enabled at (44430734): [<ffff800086932074>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:198
> > hardirqs last disabled at (44430735): [<ffff80008690cd0c>] __el1_irq arch/arm64/kernel/entry-common.c:527 [inline]
> > hardirqs last disabled at (44430735): [<ffff80008690cd0c>] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:543
> > softirqs last enabled at (6136): [<ffff80008030e6e4>] softirq_handle_end kernel/softirq.c:468 [inline]
> > softirqs last enabled at (6136): [<ffff80008030e6e4>] handle_softirqs+0xc28/0xd98 kernel/softirq.c:650
> > softirqs last disabled at (7461): [<ffff8000800204c0>] __do_softirq+0x14/0x20 kernel/softirq.c:656
> >
> >
> > ---
> > If you want syzbot to run the reproducer, reply with:
> > #syz test: git://repo/address.git branch-or-commit-hash
> > If you attach or paste a git patch, syzbot will apply it before testing.
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-09-04 13:51 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2026-08-08 20:09 [syzbot] [kernel?] INFO: rcu detected stall in __hrtimer_run_queues (3) syzbot
2026-08-31 15:55 ` syzbot
2026-09-04 5:00 ` Thomas Gleixner
2026-09-04 13:51 ` Aleksandr Nogikh
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