[v5.15] INFO: rcu detected stall in sys_mprotect (3)
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syzbot
Oct 28, 2025, 8:28:24 AM (6 days ago) Oct 28
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: ac56c046adf4 Linux 5.15.195
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=117c6932580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=7ed51ba1ac7cb5d53a14
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c11ec9487150/disk-ac56c046.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f1130a72d3a0/vmlinux-ac56c046.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7608cb6a3be5/bzImage-ac56c046.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7ed51b...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 GPs behind) idle=b85/1/0x4000000000000000 softirq=61056/61057 fqs=0
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P3561/1:b..l
(detected by 0, t=10506 jiffies, g=83113, q=52)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4342 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__lock_release kernel/locking/lockdep.c:5279 [inline]
RIP: 0010:lock_release+0x15d/0x870 kernel/locking/lockdep.c:5643
Code: 00 9c 8f 84 24 a0 00 00 00 48 8b 84 24 a0 00 00 00 48 89 44 24 50 fa 48 c7 c7 a0 26 0b 8a e8 aa e3 4c 08 65 ff 05 e3 fd a5 7e <c7> 44 24 5c 01 00 00 00 48 c7 c0 04 ce 69 8d 48 c1 e8 03 42 0f b6
RSP: 0018:ffffc90000dd0b40 EFLAGS: 00000002
RAX: 0000000000000001 RBX: ffff88807b1f0000 RCX: 2ec74196e72c9500
RDX: 0000000000000000 RSI: ffffffff8a0b26a0 RDI: ffffffff8a59a880
RBP: ffffc90000dd0c50 R08: dffffc0000000000 R09: fffffbfff1ad334e
R10: fffffbfff1ad334e R11: 1ffffffff1ad334d R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff88807b1f0aec R15: 1ffff920001ba174
FS: 00007f5c70283880(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5c6f917000 CR3: 00000000736f9000 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:1653 [inline]
__hrtimer_run_queues+0x2db/0xc40 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
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:lock_release+0x584/0x870 kernel/locking/lockdep.c:5647
Code: 00 00 00 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 75 75 f7 44 24 50 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 2f 00 00 00 00 66 43 c7 44 2f 09 00 00 43 c6 44 2f 0b 00
RSP: 0018:ffffc9000405f940 EFLAGS: 00000206
RAX: 0000000000000001 RBX: bba975c5d86defc7 RCX: 2ec74196e72c9500
RDX: 0000000000000001 RSI: ffffffff8a0b2b40 RDI: ffffffff8a59a880
RBP: ffffc9000405fa50 R08: dffffc0000000000 R09: fffffbfff1ad334e
R10: fffffbfff1ad334e R11: 1ffffffff1ad334d R12: ffff88807b1f0b18
R13: dffffc0000000000 R14: ffff88807b1f0ae0 R15: 1ffff9200080bf34
__raw_spin_unlock include/linux/spinlock_api_smp.h:150 [inline]
_raw_spin_unlock+0x12/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:404 [inline]
browse_rb mm/mmap.c:363 [inline]
validate_mm+0x4e2/0x950 mm/mmap.c:423
__vma_adjust+0x1b6c/0x1c20 mm/mmap.c:1029
vma_merge+0xad2/0xd00 mm/mmap.c:1238
mprotect_fixup+0x424/0x800 mm/mprotect.c:465
do_mprotect_pkey+0x657/0x910 mm/mprotect.c:636
__do_sys_mprotect mm/mprotect.c:662 [inline]
__se_sys_mprotect mm/mprotect.c:659 [inline]
__x64_sys_mprotect+0x7c/0x90 mm/mprotect.c:659
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: 0033:0x7f5c703e7fe7
Code: ef e8 3d fa ff ff 84 c0 75 b9 31 db 48 83 c4 08 48 89 d8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 0f 1f 44 00 00 b8 0a 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 2d 0d 00 f7 d8 64 89 01 48
RSP: 002b:00007fff9cb21ca8 EFLAGS: 00000246 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 0000000000000200 RCX: 00007f5c703e7fe7
RDX: 0000000000000001 RSI: 0000000000000200 RDI: 00007f5c6f917000
RBP: 0000563e707e8050 R08: 0000000000000000 R09: 0000000000000200
R10: 0000563e707e80b0 R11: 0000000000000246 R12: 00000000000001f6
R13: 0000000000000e00 R14: 0000563e707f3418 R15: 00007f5c70ac739c
</TASK>
task:udevd state:R running task stack:22848 pid: 3561 ppid: 1 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:seqcount_lockdep_reader_access+0x17a/0x1c0 include/linux/seqlock.h:106
Code: ff 4d 85 ed 75 16 e8 55 49 ad ff eb 15 e8 4e 49 ad ff e8 99 cc de 07 4d 85 ed 74 ea e8 3f 49 ad ff fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 27 00 00 00 00 66 43 c7 44 27 09 00 00 43 c6 44 27 0b 00
RSP: 0018:ffffc90002e1f700 EFLAGS: 00000293
RAX: ffffffff81ca8151 RBX: 0000000000000000 RCX: ffff88807bd10000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90002e1f7b0 R08: dffffc0000000000 R09: fffffbfff1ad334e
R10: fffffbfff1ad334e R11: 1ffffffff1ad334d R12: dffffc0000000000
R13: 0000000000000200 R14: ffffffff81ca8fc2 R15: 1ffff920005c3ee0
__follow_mount_rcu fs/namei.c:1465 [inline]
handle_mounts fs/namei.c:1498 [inline]
step_into+0x642/0xd00 fs/namei.c:1814
link_path_walk+0x662/0xd40 fs/namei.c:-1
path_lookupat+0x9d/0x440 fs/namei.c:2462
filename_lookup+0x1e2/0x4f0 fs/namei.c:2492
user_path_at_empty+0x40/0x190 fs/namei.c:2891
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0x102/0x4d0 fs/stat.c:221
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat fs/stat.c:411 [inline]
__se_sys_newfstatat fs/stat.c:405 [inline]
__x64_sys_newfstatat+0x12c/0x1b0 fs/stat.c:405
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: 0033:0x7f5c703dbb0a
RSP: 002b:00007fff9cb26a68 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
RAX: ffffffffffffffda RBX: 00007fff9cb26f00 RCX: 00007f5c703dbb0a
RDX: 00007fff9cb26a70 RSI: 00007fff9cb26f00 RDI: 00000000ffffff9c
RBP: 0000563e707da910 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff9cb26b00
R13: 0000000000000100 R14: 0000563e52207be0 R15: 00007fff9cb27580
</TASK>
rcu: rcu_preempt kthread starved for 10506 jiffies! g83113 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: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 0
CPU: 0 PID: 14745 Comm: syz.4.2051 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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]
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:1685 [inline]
__hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
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 66 49 0b 00 83 e3 01 75 07 e8 fc 45 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:ffffc90003e8fbe0 EFLAGS: 00000246
RAX: ffffffff816c84bb RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc90015491000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc90003e8fd20 R08: dffffc0000000000 R09: fffffbfff1ff7a3a
R10: fffffbfff1ff7a3a R11: 1ffffffff1ff7a39 R12: ffff8880b91405c8
R13: 1ffff110172280b9 R14: ffff8880b903b3c0 R15: 0000000000000001
on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1134
on_each_cpu include/linux/smp.h:71 [inline]
hardware_enable_all+0x7a/0x120 virt/kvm/kvm_main.c:4921
kvm_create_vm virt/kvm/kvm_main.c:1148 [inline]
kvm_dev_ioctl_create_vm virt/kvm/kvm_main.c:4754 [inline]
kvm_dev_ioctl+0x1239/0x2040 virt/kvm/kvm_main.c:4809
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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: 0033:0x7fb0bb3a2fc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007fb0b960a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb0bb5f9fa0 RCX: 00007fb0bb3a2fc9
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000006
RBP: 00007fb0bb425f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb0bb5fa038 R14: 00007fb0bb5f9fa0 R15: 00007fff07fc13b8
</TASK>
---
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If you want to undo deduplication, reply with:
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syzbot found the following issue on:
HEAD commit: ac56c046adf4 Linux 5.15.195
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=117c6932580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=7ed51ba1ac7cb5d53a14
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c11ec9487150/disk-ac56c046.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f1130a72d3a0/vmlinux-ac56c046.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7608cb6a3be5/bzImage-ac56c046.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7ed51b...@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 GPs behind) idle=b85/1/0x4000000000000000 softirq=61056/61057 fqs=0
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P3561/1:b..l
(detected by 0, t=10506 jiffies, g=83113, q=52)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4342 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__lock_release kernel/locking/lockdep.c:5279 [inline]
RIP: 0010:lock_release+0x15d/0x870 kernel/locking/lockdep.c:5643
Code: 00 9c 8f 84 24 a0 00 00 00 48 8b 84 24 a0 00 00 00 48 89 44 24 50 fa 48 c7 c7 a0 26 0b 8a e8 aa e3 4c 08 65 ff 05 e3 fd a5 7e <c7> 44 24 5c 01 00 00 00 48 c7 c0 04 ce 69 8d 48 c1 e8 03 42 0f b6
RSP: 0018:ffffc90000dd0b40 EFLAGS: 00000002
RAX: 0000000000000001 RBX: ffff88807b1f0000 RCX: 2ec74196e72c9500
RDX: 0000000000000000 RSI: ffffffff8a0b26a0 RDI: ffffffff8a59a880
RBP: ffffc90000dd0c50 R08: dffffc0000000000 R09: fffffbfff1ad334e
R10: fffffbfff1ad334e R11: 1ffffffff1ad334d R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff88807b1f0aec R15: 1ffff920001ba174
FS: 00007f5c70283880(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5c6f917000 CR3: 00000000736f9000 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:1653 [inline]
__hrtimer_run_queues+0x2db/0xc40 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
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:lock_release+0x584/0x870 kernel/locking/lockdep.c:5647
Code: 00 00 00 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 75 75 f7 44 24 50 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 2f 00 00 00 00 66 43 c7 44 2f 09 00 00 43 c6 44 2f 0b 00
RSP: 0018:ffffc9000405f940 EFLAGS: 00000206
RAX: 0000000000000001 RBX: bba975c5d86defc7 RCX: 2ec74196e72c9500
RDX: 0000000000000001 RSI: ffffffff8a0b2b40 RDI: ffffffff8a59a880
RBP: ffffc9000405fa50 R08: dffffc0000000000 R09: fffffbfff1ad334e
R10: fffffbfff1ad334e R11: 1ffffffff1ad334d R12: ffff88807b1f0b18
R13: dffffc0000000000 R14: ffff88807b1f0ae0 R15: 1ffff9200080bf34
__raw_spin_unlock include/linux/spinlock_api_smp.h:150 [inline]
_raw_spin_unlock+0x12/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:404 [inline]
browse_rb mm/mmap.c:363 [inline]
validate_mm+0x4e2/0x950 mm/mmap.c:423
__vma_adjust+0x1b6c/0x1c20 mm/mmap.c:1029
vma_merge+0xad2/0xd00 mm/mmap.c:1238
mprotect_fixup+0x424/0x800 mm/mprotect.c:465
do_mprotect_pkey+0x657/0x910 mm/mprotect.c:636
__do_sys_mprotect mm/mprotect.c:662 [inline]
__se_sys_mprotect mm/mprotect.c:659 [inline]
__x64_sys_mprotect+0x7c/0x90 mm/mprotect.c:659
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: 0033:0x7f5c703e7fe7
Code: ef e8 3d fa ff ff 84 c0 75 b9 31 db 48 83 c4 08 48 89 d8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 0f 1f 44 00 00 b8 0a 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 2d 0d 00 f7 d8 64 89 01 48
RSP: 002b:00007fff9cb21ca8 EFLAGS: 00000246 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 0000000000000200 RCX: 00007f5c703e7fe7
RDX: 0000000000000001 RSI: 0000000000000200 RDI: 00007f5c6f917000
RBP: 0000563e707e8050 R08: 0000000000000000 R09: 0000000000000200
R10: 0000563e707e80b0 R11: 0000000000000246 R12: 00000000000001f6
R13: 0000000000000e00 R14: 0000563e707f3418 R15: 00007f5c70ac739c
</TASK>
task:udevd state:R running task stack:22848 pid: 3561 ppid: 1 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:seqcount_lockdep_reader_access+0x17a/0x1c0 include/linux/seqlock.h:106
Code: ff 4d 85 ed 75 16 e8 55 49 ad ff eb 15 e8 4e 49 ad ff e8 99 cc de 07 4d 85 ed 74 ea e8 3f 49 ad ff fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 27 00 00 00 00 66 43 c7 44 27 09 00 00 43 c6 44 27 0b 00
RSP: 0018:ffffc90002e1f700 EFLAGS: 00000293
RAX: ffffffff81ca8151 RBX: 0000000000000000 RCX: ffff88807bd10000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90002e1f7b0 R08: dffffc0000000000 R09: fffffbfff1ad334e
R10: fffffbfff1ad334e R11: 1ffffffff1ad334d R12: dffffc0000000000
R13: 0000000000000200 R14: ffffffff81ca8fc2 R15: 1ffff920005c3ee0
__follow_mount_rcu fs/namei.c:1465 [inline]
handle_mounts fs/namei.c:1498 [inline]
step_into+0x642/0xd00 fs/namei.c:1814
link_path_walk+0x662/0xd40 fs/namei.c:-1
path_lookupat+0x9d/0x440 fs/namei.c:2462
filename_lookup+0x1e2/0x4f0 fs/namei.c:2492
user_path_at_empty+0x40/0x190 fs/namei.c:2891
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0x102/0x4d0 fs/stat.c:221
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat fs/stat.c:411 [inline]
__se_sys_newfstatat fs/stat.c:405 [inline]
__x64_sys_newfstatat+0x12c/0x1b0 fs/stat.c:405
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: 0033:0x7f5c703dbb0a
RSP: 002b:00007fff9cb26a68 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
RAX: ffffffffffffffda RBX: 00007fff9cb26f00 RCX: 00007f5c703dbb0a
RDX: 00007fff9cb26a70 RSI: 00007fff9cb26f00 RDI: 00000000ffffff9c
RBP: 0000563e707da910 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff9cb26b00
R13: 0000000000000100 R14: 0000563e52207be0 R15: 00007fff9cb27580
</TASK>
rcu: rcu_preempt kthread starved for 10506 jiffies! g83113 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: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 0
CPU: 0 PID: 14745 Comm: syz.4.2051 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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]
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:1685 [inline]
__hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
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 66 49 0b 00 83 e3 01 75 07 e8 fc 45 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:ffffc90003e8fbe0 EFLAGS: 00000246
RAX: ffffffff816c84bb RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc90015491000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc90003e8fd20 R08: dffffc0000000000 R09: fffffbfff1ff7a3a
R10: fffffbfff1ff7a3a R11: 1ffffffff1ff7a39 R12: ffff8880b91405c8
R13: 1ffff110172280b9 R14: ffff8880b903b3c0 R15: 0000000000000001
on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1134
on_each_cpu include/linux/smp.h:71 [inline]
hardware_enable_all+0x7a/0x120 virt/kvm/kvm_main.c:4921
kvm_create_vm virt/kvm/kvm_main.c:1148 [inline]
kvm_dev_ioctl_create_vm virt/kvm/kvm_main.c:4754 [inline]
kvm_dev_ioctl+0x1239/0x2040 virt/kvm/kvm_main.c:4809
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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: 0033:0x7fb0bb3a2fc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007fb0b960a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb0bb5f9fa0 RCX: 00007fb0bb3a2fc9
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000006
RBP: 00007fb0bb425f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb0bb5fa038 R14: 00007fb0bb5f9fa0 R15: 00007fff07fc13b8
</TASK>
---
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