[v5.15] INFO: rcu detected stall in pwq_unbound_release_workfn (2)
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syzbot
May 28, 2025, 1:46:28 PMMay 28
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Hello,
syzbot found the following issue on:
HEAD commit: 98f47d0e9b8c Linux 5.15.184
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12d86bf4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d966a9f787a9782
dashboard link: https://syzkaller.appspot.com/bug?extid=3779eaac5078e34be805
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5e51314fa9b0/disk-98f47d0e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3348ed80ea4e/vmlinux-98f47d0e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3e02a814f2cc/bzImage-98f47d0e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3779ea...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 GPs behind) idle=4a5/1/0x4000000000000000 softirq=44495/44496 fqs=32
(detected by 0, t=10502 jiffies, g=60861, q=415)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7059 Comm: kworker/1:15 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events pwq_unbound_release_workfn
RIP: 0010:find_held_lock kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__lock_release kernel/locking/lockdep.c:5300 [inline]
RIP: 0010:lock_release+0x1fc/0x870 kernel/locking/lockdep.c:5643
Code: 89 4c 24 28 83 f9 32 0f 83 ca 04 00 00 4b 8d 04 b6 4c 8d 24 c3 48 89 c3 4c 89 e7 48 8b 74 24 08 e8 89 c9 44 08 44 89 7c 24 3c <44> 89 fa 85 c0 0f 84 d2 01 00 00 4d 85 e4 0f 84 0b 03 00 00 4d 8d
RSP: 0018:ffffc90000dd0b40 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 000000000000000f RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff96350c00 RDI: ffff88802776a928
RBP: ffffc90000dd0c50 R08: dffffc0000000000 R09: fffffbfff1ad1556
R10: fffffbfff1ad1556 R11: 1ffffffff1ad1555 R12: ffff88802776a928
R13: dffffc0000000000 R14: 0000000000000003 R15: 0000000000000003
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000006038 CR3: 000000007e03c000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:158 [inline]
_raw_spin_unlock_irqrestore+0x6d/0x100 kernel/locking/spinlock.c:194
debug_hrtimer_deactivate kernel/time/hrtimer.c:415 [inline]
debug_deactivate+0x1d/0x1c0 kernel/time/hrtimer.c:471
__run_hrtimer kernel/time/hrtimer.c:1658 [inline]
__hrtimer_run_queues+0x2db/0xc40 kernel/time/hrtimer.c:1754
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lockdep_unregister_key+0x4ae/0x500 kernel/locking/lockdep.c:6334
Code: 48 3b 84 24 80 00 00 00 75 39 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 ee a1 44 08 41 f7 c4 00 02 00 00 74 8b fb 84 db <75> 8a eb 9b 0f 0b e9 58 ff ff ff 0f 0b e9 c4 fe ff ff 0f 0b e9 11
RSP: 0018:ffffc9000436fb20 EFLAGS: 00000246
RAX: f870370f2cca1600 RBX: 0000000000000000 RCX: f870370f2cca1600
RDX: 0000000000000001 RSI: ffffffff8a0b1fc0 RDI: ffffffff8a59a700
RBP: ffffc9000436fbf0 R08: dffffc0000000000 R09: fffffbfff1fedbc9
R10: fffffbfff1fedbc9 R11: 1ffffffff1fedbc8 R12: 0000000000000a07
R13: ffff88807b34a129 R14: ffffffff8ff6b028 R15: 1ffff9200086df68
wq_unregister_lockdep kernel/workqueue.c:3518 [inline]
pwq_unbound_release_workfn+0x262/0x2b0 kernel/workqueue.c:3756
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: rcu_preempt kthread starved for 10438 jiffies! g60861 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:28032 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5030 [inline]
__schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
schedule+0x11b/0x1e0 kernel/sched/core.c:6459
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 13244 Comm: syz.8.2858 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<IRQ>
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592
check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
rcu_pending kernel/rcu/tree.c:3932 [inline]
rcu_sched_clock_irq+0x831/0x1110 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:1818
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1690 [inline]
__hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0xb88/0xd70 kernel/smp.c:969
Code: b6 44 05 00 84 c0 0f 85 9d 00 00 00 41 8b 1c 24 89 de 83 e6 01 31 ff e8 a6 55 0b 00 83 e3 01 75 07 e8 3c 52 0b 00 eb 43 f3 90 <48> b8 00 00 00 00 00 fc ff df 41 0f b6 44 05 00 84 c0 75 11 41 f7
RSP: 0018:ffffc900041af1c0 EFLAGS: 00000246
RAX: ffffffff816c6f2b RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc9000f7bd000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc900041af300 R08: dffffc0000000000 R09: fffffbfff1ff3647
R10: fffffbfff1ff3647 R11: 1ffffffff1ff3646 R12: ffff8880b9140588
R13: 1ffff110172280b1 R14: ffff8880b903b380 R15: 0000000000000001
on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1135
kill_bdev block/bdev.c:76 [inline]
set_blocksize+0x2eb/0x370 block/bdev.c:157
sb_set_blocksize+0x45/0xe0 block/bdev.c:166
ocfs2_get_sector+0x9b/0x4a0 fs/ocfs2/super.c:1757
ocfs2_sb_probe fs/ocfs2/super.c:748 [inline]
ocfs2_fill_super+0x3cd/0x4d80 fs/ocfs2/super.c:989
mount_bdev+0x287/0x3c0 fs/super.c:1400
legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x24a/0xa40 fs/namespace.c:3014
do_mount fs/namespace.c:3357 [inline]
__do_sys_mount fs/namespace.c:3565 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3542
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f5b9b84a10a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5b996afe68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f5b996afef0 RCX: 00007f5b9b84a10a
RDX: 0000200000004440 RSI: 0000200000000040 RDI: 00007f5b996afeb0
RBP: 0000200000004440 R08: 00007f5b996afef0 R09: 00000000000008c0
R10: 00000000000008c0 R11: 0000000000000246 R12: 0000200000000040
R13: 00007f5b996afeb0 R14: 000000000000442b R15: 00002000000001c0
</TASK>
---
This report is generated by a bot. It may contain errors.
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If you want to undo deduplication, reply with:
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syzbot found the following issue on:
HEAD commit: 98f47d0e9b8c Linux 5.15.184
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12d86bf4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d966a9f787a9782
dashboard link: https://syzkaller.appspot.com/bug?extid=3779eaac5078e34be805
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5e51314fa9b0/disk-98f47d0e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3348ed80ea4e/vmlinux-98f47d0e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3e02a814f2cc/bzImage-98f47d0e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3779ea...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 GPs behind) idle=4a5/1/0x4000000000000000 softirq=44495/44496 fqs=32
(detected by 0, t=10502 jiffies, g=60861, q=415)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7059 Comm: kworker/1:15 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events pwq_unbound_release_workfn
RIP: 0010:find_held_lock kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__lock_release kernel/locking/lockdep.c:5300 [inline]
RIP: 0010:lock_release+0x1fc/0x870 kernel/locking/lockdep.c:5643
Code: 89 4c 24 28 83 f9 32 0f 83 ca 04 00 00 4b 8d 04 b6 4c 8d 24 c3 48 89 c3 4c 89 e7 48 8b 74 24 08 e8 89 c9 44 08 44 89 7c 24 3c <44> 89 fa 85 c0 0f 84 d2 01 00 00 4d 85 e4 0f 84 0b 03 00 00 4d 8d
RSP: 0018:ffffc90000dd0b40 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 000000000000000f RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff96350c00 RDI: ffff88802776a928
RBP: ffffc90000dd0c50 R08: dffffc0000000000 R09: fffffbfff1ad1556
R10: fffffbfff1ad1556 R11: 1ffffffff1ad1555 R12: ffff88802776a928
R13: dffffc0000000000 R14: 0000000000000003 R15: 0000000000000003
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000006038 CR3: 000000007e03c000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:158 [inline]
_raw_spin_unlock_irqrestore+0x6d/0x100 kernel/locking/spinlock.c:194
debug_hrtimer_deactivate kernel/time/hrtimer.c:415 [inline]
debug_deactivate+0x1d/0x1c0 kernel/time/hrtimer.c:471
__run_hrtimer kernel/time/hrtimer.c:1658 [inline]
__hrtimer_run_queues+0x2db/0xc40 kernel/time/hrtimer.c:1754
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lockdep_unregister_key+0x4ae/0x500 kernel/locking/lockdep.c:6334
Code: 48 3b 84 24 80 00 00 00 75 39 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 ee a1 44 08 41 f7 c4 00 02 00 00 74 8b fb 84 db <75> 8a eb 9b 0f 0b e9 58 ff ff ff 0f 0b e9 c4 fe ff ff 0f 0b e9 11
RSP: 0018:ffffc9000436fb20 EFLAGS: 00000246
RAX: f870370f2cca1600 RBX: 0000000000000000 RCX: f870370f2cca1600
RDX: 0000000000000001 RSI: ffffffff8a0b1fc0 RDI: ffffffff8a59a700
RBP: ffffc9000436fbf0 R08: dffffc0000000000 R09: fffffbfff1fedbc9
R10: fffffbfff1fedbc9 R11: 1ffffffff1fedbc8 R12: 0000000000000a07
R13: ffff88807b34a129 R14: ffffffff8ff6b028 R15: 1ffff9200086df68
wq_unregister_lockdep kernel/workqueue.c:3518 [inline]
pwq_unbound_release_workfn+0x262/0x2b0 kernel/workqueue.c:3756
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: rcu_preempt kthread starved for 10438 jiffies! g60861 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:28032 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5030 [inline]
__schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
schedule+0x11b/0x1e0 kernel/sched/core.c:6459
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 13244 Comm: syz.8.2858 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<IRQ>
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592
check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
rcu_pending kernel/rcu/tree.c:3932 [inline]
rcu_sched_clock_irq+0x831/0x1110 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:1818
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1690 [inline]
__hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0xb88/0xd70 kernel/smp.c:969
Code: b6 44 05 00 84 c0 0f 85 9d 00 00 00 41 8b 1c 24 89 de 83 e6 01 31 ff e8 a6 55 0b 00 83 e3 01 75 07 e8 3c 52 0b 00 eb 43 f3 90 <48> b8 00 00 00 00 00 fc ff df 41 0f b6 44 05 00 84 c0 75 11 41 f7
RSP: 0018:ffffc900041af1c0 EFLAGS: 00000246
RAX: ffffffff816c6f2b RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc9000f7bd000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc900041af300 R08: dffffc0000000000 R09: fffffbfff1ff3647
R10: fffffbfff1ff3647 R11: 1ffffffff1ff3646 R12: ffff8880b9140588
R13: 1ffff110172280b1 R14: ffff8880b903b380 R15: 0000000000000001
on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1135
kill_bdev block/bdev.c:76 [inline]
set_blocksize+0x2eb/0x370 block/bdev.c:157
sb_set_blocksize+0x45/0xe0 block/bdev.c:166
ocfs2_get_sector+0x9b/0x4a0 fs/ocfs2/super.c:1757
ocfs2_sb_probe fs/ocfs2/super.c:748 [inline]
ocfs2_fill_super+0x3cd/0x4d80 fs/ocfs2/super.c:989
mount_bdev+0x287/0x3c0 fs/super.c:1400
legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x24a/0xa40 fs/namespace.c:3014
do_mount fs/namespace.c:3357 [inline]
__do_sys_mount fs/namespace.c:3565 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3542
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f5b9b84a10a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5b996afe68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f5b996afef0 RCX: 00007f5b9b84a10a
RDX: 0000200000004440 RSI: 0000200000000040 RDI: 00007f5b996afeb0
RBP: 0000200000004440 R08: 00007f5b996afef0 R09: 00000000000008c0
R10: 00000000000008c0 R11: 0000000000000246 R12: 0000200000000040
R13: 00007f5b996afeb0 R14: 000000000000442b R15: 00002000000001c0
</TASK>
---
This report is generated by a bot. It may contain errors.
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If you want to overwrite report's subsystems, reply with:
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If you want to undo deduplication, reply with:
#syz undup
syzbot
Sep 2, 2025, 4:33:35 AM (5 days ago) Sep 2
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:
HEAD commit: 01879f56bdde Linux 5.15.190
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11c88312580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4bfb7f3ca9a4e172
dashboard link: https://syzkaller.appspot.com/bug?extid=3779eaac5078e34be805
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11308e62580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/17385e3d0303/disk-01879f56.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f9f55c135c1d/vmlinux-01879f56.xz
kernel image: https://storage.googleapis.com/syzbot-assets/aa5c288de53c/bzImage-01879f56.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3779ea...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 GPs behind) idle=05b/1/0x4000000000000002 softirq=7182/7183 fqs=181
(detected by 1, t=10502 jiffies, g=8437, q=122)
Sending NMI from CPU 1 to CPUs 0:
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
Workqueue: events pwq_unbound_release_workfn
RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x2a/0x80 kernel/kcov.c:300
Code: 48 8b 04 24 65 48 8b 0d 24 a1 8a 7e 65 8b 15 25 a1 8a 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 57 83 b9 34 16 00 00 00 <74> 4e 8b 91 10 16 00 00 83 fa 03 75 43 48 8b 91 18 16 00 00 44 8b
RSP: 0018:ffffc90000007010 EFLAGS: 00000046
RAX: ffffffff81010d1f RBX: ffff8880b9035178 RCX: ffff888018199dc0
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffc90000007180
R10: fffff52000000e37 R11: 1ffff92000000e30 R12: dffffc0000000000
R13: ffffc900000071e6 R14: 0000000000000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
perf_misc_flags+0x13f/0x1b0 arch/x86/events/core.c:2970
perf_prepare_sample+0x132/0x1cb0 kernel/events/core.c:7622
__perf_event_output kernel/events/core.c:7802 [inline]
perf_event_output_forward+0x146/0x280 kernel/events/core.c:7822
__perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
perf_tp_event+0x32c/0xb50 kernel/events/core.c:10047
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
perf_trace_preemptirq_template+0x2be/0x380 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x84/0x480 kernel/rcu/tree_plugin.h:674
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 dd 13 9e 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc90000007780 EFLAGS: 00000206
RAX: 186c6fb277b72400 RBX: 1ffff92000000ef4 RCX: 186c6fb277b72400
RDX: dffffc0000000000 RSI: ffffffff8a0b1620 RDI: ffffffff8a59a240
RBP: ffffc90000007860 R08: dffffc0000000000 R09: fffffbfff1ff762c
R10: fffffbfff1ff762c R11: 1ffffffff1ff762b R12: ffffffff8c120900
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock include/linux/rcupdate.h:771 [inline]
__ip_queue_xmit+0x1244/0x1c00 net/ipv4/ip_output.c:533
__tcp_transmit_skb+0x1ced/0x31c0 net/ipv4/tcp_output.c:1404
tcp_delack_timer_handler+0x32e/0x730 net/ipv4/tcp_timer.c:314
tcp_delack_timer+0x188/0x2e0 net/ipv4/tcp_timer.c:341
call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
expire_timers kernel/time/timer.c:1496 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1767
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
Code: 44 24 20 f6 44 24 21 02 74 0b 0f 0b 48 f7 03 08 00 00 00 74 70 bf 01 00 00 00 e8 ff 37 a0 f7 e8 aa b0 cc f7 fb bf 01 00 00 00 <e8> ef b5 ff ff 48 c7 44 24 40 00 00 00 00 9c 8f 44 24 40 8b 44 24
RSP: 0018:ffffc9000471f9c0 EFLAGS: 00000282
RAX: 186c6fb277b72400 RBX: 0000000000000000 RCX: 186c6fb277b72400
RDX: dffffc0000000000 RSI: ffffffff8a0b1620 RDI: 0000000000000001
RBP: ffffc9000471fa60 R08: dffffc0000000000 R09: fffffbfff1ff761e
R10: fffffbfff1ff761e R11: 1ffffffff1ff761d R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff920008e3f38
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RSP: 0018:ffffc9000471fb20 EFLAGS: 00000246
RAX: 186c6fb277b72400 RBX: 0000000000000000 RCX: 186c6fb277b72400
RDX: 0000000000000001 RSI: ffffffff8a0b2420 RDI: ffffffff8a59a240
RBP: ffffc9000471fbf0 R08: dffffc0000000000 R09: fffffbfff1ff175f
R10: fffffbfff1ff175f R11: 1ffffffff1ff175e R12: 0000000000000a06
R13: ffff88805e74d129 R14: ffffffff8ff8b028 R15: 1ffff920008e3f68
rcu: Possible timer handling issue on cpu=1 timer-softirq=4943
rcu: rcu_preempt kthread starved for 10140 jiffies! g8437 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x141/0x190 arch/x86/kernel/kvm.c:918
Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 47 0f b6 1f e8 0f e1 49 00 44 38 e3 75 10 66 90 0f 00 2d e1 63 d4 08 fb f4 <e9> 33 ff ff ff fb e9 2d ff ff ff e8 df e5 74 08 89 f9 80 e1 07 38
RSP: 0018:ffffc90000dd08a0 EFLAGS: 00000246
RAX: 62805447a2e73500 RBX: 0000000000000003 RCX: 62805447a2e73500
RDX: dffffc0000000000 RSI: ffffffff8a0b1620 RDI: ffffffff8a59a240
RBP: ffffc90000dd0950 R08: dffffc0000000000 R09: fffffbfff1ff762c
R10: fffffbfff1ff762c R11: 1ffffffff1ff762b R12: 0000000000000003
R13: ffff8880b913b114 R14: dffffc0000000000 R15: 1ffff920001ba114
pv_wait arch/x86/include/asm/paravirt.h:597 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
__pv_queued_spin_lock_slowpath+0x60f/0x9c0 kernel/locking/qspinlock.c:508
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115
spin_lock include/linux/spinlock.h:363 [inline]
tcp_keepalive_timer+0x2f/0xe30 net/ipv4/tcp_timer.c:714
call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
expire_timers kernel/time/timer.c:1496 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1767
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
Code: bf 48 89 df e8 b6 f3 09 f8 eb b5 e8 3f b0 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 00 cc 66 90 0f 00 2d 77 84 53 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffc90000d67d48 EFLAGS: 000002c2
RAX: 62805447a2e73500 RBX: ffff88813fe28000 RCX: 62805447a2e73500
RDX: 0000000000000001 RSI: ffffffff8a0b1620 RDI: ffffffff8a59a240
RBP: ffffc90000d67e80 R08: dffffc0000000000 R09: ffffed101722765a
R10: ffffed101722765a R11: 1ffff11017227659 R12: ffffffff8d698ca8
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff11027fc5000
default_idle_call+0x81/0xc0 kernel/sched/idle.c:112
cpuidle_idle_call kernel/sched/idle.c:194 [inline]
do_idle+0x21b/0x5b0 kernel/sched/idle.c:306
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
start_secondary+0x31f/0x430 arch/x86/kernel/smpboot.c:281
secondary_startup_64_no_verify+0xb1/0xbb
</TASK>
---
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.
HEAD commit: 01879f56bdde Linux 5.15.190
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11c88312580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4bfb7f3ca9a4e172
dashboard link: https://syzkaller.appspot.com/bug?extid=3779eaac5078e34be805
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11308e62580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/17385e3d0303/disk-01879f56.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f9f55c135c1d/vmlinux-01879f56.xz
kernel image: https://storage.googleapis.com/syzbot-assets/aa5c288de53c/bzImage-01879f56.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3779ea...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
(detected by 1, t=10502 jiffies, g=8437, q=122)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4369 Comm: kworker/0:5 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
Workqueue: events pwq_unbound_release_workfn
RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x2a/0x80 kernel/kcov.c:300
Code: 48 8b 04 24 65 48 8b 0d 24 a1 8a 7e 65 8b 15 25 a1 8a 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 57 83 b9 34 16 00 00 00 <74> 4e 8b 91 10 16 00 00 83 fa 03 75 43 48 8b 91 18 16 00 00 44 8b
RSP: 0018:ffffc90000007010 EFLAGS: 00000046
RAX: ffffffff81010d1f RBX: ffff8880b9035178 RCX: ffff888018199dc0
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffc90000007180
R10: fffff52000000e37 R11: 1ffff92000000e30 R12: dffffc0000000000
R13: ffffc900000071e6 R14: 0000000000000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000001b58f000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
user_mode arch/x86/include/asm/ptrace.h:136 [inline]
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
perf_misc_flags+0x13f/0x1b0 arch/x86/events/core.c:2970
perf_prepare_sample+0x132/0x1cb0 kernel/events/core.c:7622
__perf_event_output kernel/events/core.c:7802 [inline]
perf_event_output_forward+0x146/0x280 kernel/events/core.c:7822
__perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
perf_tp_event+0x32c/0xb50 kernel/events/core.c:10047
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
perf_trace_preemptirq_template+0x2be/0x380 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x84/0x480 kernel/rcu/tree_plugin.h:674
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 dd 13 9e 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc90000007780 EFLAGS: 00000206
RAX: 186c6fb277b72400 RBX: 1ffff92000000ef4 RCX: 186c6fb277b72400
RDX: dffffc0000000000 RSI: ffffffff8a0b1620 RDI: ffffffff8a59a240
RBP: ffffc90000007860 R08: dffffc0000000000 R09: fffffbfff1ff762c
R10: fffffbfff1ff762c R11: 1ffffffff1ff762b R12: ffffffff8c120900
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock include/linux/rcupdate.h:771 [inline]
__ip_queue_xmit+0x1244/0x1c00 net/ipv4/ip_output.c:533
__tcp_transmit_skb+0x1ced/0x31c0 net/ipv4/tcp_output.c:1404
tcp_delack_timer_handler+0x32e/0x730 net/ipv4/tcp_timer.c:314
tcp_delack_timer+0x188/0x2e0 net/ipv4/tcp_timer.c:341
call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
expire_timers kernel/time/timer.c:1496 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1767
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:preempt_schedule_irq+0xac/0x150 kernel/sched/core.c:6799
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
Code: 44 24 20 f6 44 24 21 02 74 0b 0f 0b 48 f7 03 08 00 00 00 74 70 bf 01 00 00 00 e8 ff 37 a0 f7 e8 aa b0 cc f7 fb bf 01 00 00 00 <e8> ef b5 ff ff 48 c7 44 24 40 00 00 00 00 9c 8f 44 24 40 8b 44 24
RSP: 0018:ffffc9000471f9c0 EFLAGS: 00000282
RAX: 186c6fb277b72400 RBX: 0000000000000000 RCX: 186c6fb277b72400
RDX: dffffc0000000000 RSI: ffffffff8a0b1620 RDI: 0000000000000001
RBP: ffffc9000471fa60 R08: dffffc0000000000 R09: fffffbfff1ff761e
R10: fffffbfff1ff761e R11: 1ffffffff1ff761d R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff920008e3f38
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:lockdep_unregister_key+0x4ae/0x500 kernel/locking/lockdep.c:6334
Code: 48 3b 84 24 80 00 00 00 75 39 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 be 4f 4c 08 41 f7 c4 00 02 00 00 74 8b fb 84 db <75> 8a eb 9b 0f 0b e9 58 ff ff ff 0f 0b e9 c4 fe ff ff 0f 0b e9 11
RSP: 0018:ffffc9000471fb20 EFLAGS: 00000246
RAX: 186c6fb277b72400 RBX: 0000000000000000 RCX: 186c6fb277b72400
RDX: 0000000000000001 RSI: ffffffff8a0b2420 RDI: ffffffff8a59a240
RBP: ffffc9000471fbf0 R08: dffffc0000000000 R09: fffffbfff1ff175f
R10: fffffbfff1ff175f R11: 1ffffffff1ff175e R12: 0000000000000a06
R13: ffff88805e74d129 R14: ffffffff8ff8b028 R15: 1ffff920008e3f68
wq_unregister_lockdep kernel/workqueue.c:3518 [inline]
pwq_unbound_release_workfn+0x262/0x2b0 kernel/workqueue.c:3756
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10139 jiffies! g8437 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
pwq_unbound_release_workfn+0x262/0x2b0 kernel/workqueue.c:3756
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: Possible timer handling issue on cpu=1 timer-softirq=4943
rcu: rcu_preempt kthread starved for 10140 jiffies! g8437 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
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:27104 pid: 15 ppid: 2 flags:0x00004000
rcu: RCU grace-period kthread stack dump:
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
Call Trace:
<IRQ>
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592
check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
<IRQ>
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592
check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
rcu_sched_clock_irq+0x831/0x1110 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:1818
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1690 [inline]
__hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
update_process_times+0x193/0x200 kernel/time/timer.c:1818
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1690 [inline]
__hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x141/0x190 arch/x86/kernel/kvm.c:918
Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 47 0f b6 1f e8 0f e1 49 00 44 38 e3 75 10 66 90 0f 00 2d e1 63 d4 08 fb f4 <e9> 33 ff ff ff fb e9 2d ff ff ff e8 df e5 74 08 89 f9 80 e1 07 38
RSP: 0018:ffffc90000dd08a0 EFLAGS: 00000246
RAX: 62805447a2e73500 RBX: 0000000000000003 RCX: 62805447a2e73500
RDX: dffffc0000000000 RSI: ffffffff8a0b1620 RDI: ffffffff8a59a240
RBP: ffffc90000dd0950 R08: dffffc0000000000 R09: fffffbfff1ff762c
R10: fffffbfff1ff762c R11: 1ffffffff1ff762b R12: 0000000000000003
R13: ffff8880b913b114 R14: dffffc0000000000 R15: 1ffff920001ba114
pv_wait arch/x86/include/asm/paravirt.h:597 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
__pv_queued_spin_lock_slowpath+0x60f/0x9c0 kernel/locking/qspinlock.c:508
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115
spin_lock include/linux/spinlock.h:363 [inline]
tcp_keepalive_timer+0x2f/0xe30 net/ipv4/tcp_timer.c:714
call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
expire_timers kernel/time/timer.c:1496 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1767
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:730
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
Code: bf 48 89 df e8 b6 f3 09 f8 eb b5 e8 3f b0 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 00 cc 66 90 0f 00 2d 77 84 53 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffc90000d67d48 EFLAGS: 000002c2
RAX: 62805447a2e73500 RBX: ffff88813fe28000 RCX: 62805447a2e73500
RDX: 0000000000000001 RSI: ffffffff8a0b1620 RDI: ffffffff8a59a240
RBP: ffffc90000d67e80 R08: dffffc0000000000 R09: ffffed101722765a
R10: ffffed101722765a R11: 1ffff11017227659 R12: ffffffff8d698ca8
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff11027fc5000
default_idle_call+0x81/0xc0 kernel/sched/idle.c:112
cpuidle_idle_call kernel/sched/idle.c:194 [inline]
do_idle+0x21b/0x5b0 kernel/sched/idle.c:306
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
start_secondary+0x31f/0x430 arch/x86/kernel/smpboot.c:281
secondary_startup_64_no_verify+0xb1/0xbb
</TASK>
---
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