rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4786/1:b..l
(detected by 0, t=10502 jiffies, g=10421, q=63)
task:udevadm state:R running task stack:26368 pid: 4786 ppid: 4177 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:__follow_mount_rcu fs/namei.c:1464 [inline]
RIP: 0010:handle_mounts fs/namei.c:1498 [inline]
RIP: 0010:step_into+0x61c/0xd00 fs/namei.c:1814
Code: 00 00 fc ff df 42 80 3c 31 00 74 0e 49 89 c4 48 89 c7 e8 d7 a2 f1 ff 4c 89 e0 4c 8b 20 4c 89 a4 24 a8 00 00 00 48 8b 44 24 70 <42> 0f b6 04 30 84 c0 0f 85 d5 01 00 00 48 8b 44 24 58 80 08 04 4c
RSP: 0018:ffffc9000368f940 EFLAGS: 00000246
RAX: 1ffff920006d1f93 RBX: ffffc9000368fc60 RCX: 1ffff11002eb2334
RDX: 0000000000000000 RSI: 000000000000000e RDI: 0000000000000040
RBP: ffffc9000368fa50 R08: 0000000000000002 R09: ffffed1028f8f06d
R10: ffffed1028f8f06d R11: 1ffff11028f8f06c R12: ffff888020576a48
R13: 1ffff920006d1f93 R14: dffffc0000000000 R15: ffff888147c782f0
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
do_readlinkat+0xd4/0x480 fs/stat.c:442
__do_sys_readlink fs/stat.c:475 [inline]
__se_sys_readlink fs/stat.c:472 [inline]
__x64_sys_readlink+0x7b/0x90 fs/stat.c:472
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: 0033:0x7f494f7823a7
RSP: 002b:00007ffcd685b408 EFLAGS: 00000206 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffcd685bc50 RCX: 00007f494f7823a7
RDX: 0000000000000400 RSI: 00007ffcd685b810 RDI: 00007ffcd685b410
RBP: 0000000000000200 R08: 000056356cd3fae2 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffcd685b410
R13: 00007ffcd685b810 R14: 000056357f55bd60 R15: 000056357f56be60
</TASK>
rcu: rcu_preempt kthread starved for 10533 jiffies! g10421 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:28064 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
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571
preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6596
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
_raw_spin_unlock_irqrestore+0xf6/0x100 kernel/locking/spinlock.c:194
__mod_timer+0x8ee/0xd20 kernel/time/timer.c:1065
schedule_timeout+0x157/0x280 kernel/time/timer.c:1913
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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4746 Comm: syz.0.119 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:lock_acquire+0x1d/0x3f0 kernel/locking/lockdep.c:5591
Code: e1 75 a6 7e a9 00 ff ff 00 0f 95 c0 c3 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec e0 00 00 00 4c 89 4c 24 20 <4c> 89 44 24 30 48 89 4c 24 28 89 d3 89 74 24 1c 49 89 fc 65 48 8b
RSP: 0018:ffffc90000dd0b60 EFLAGS: 00000086
RAX: 0000000000010001 RBX: ffff8880b912a240 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880b912a258
RBP: ffffc90000dd0c68 R08: 0000000000000001 R09: 0000000000000000
R10: fffffbfff1ad33a6 R11: 1ffffffff1ad33a5 R12: ffff8880b912a350
R13: 1ffff1101722546a R14: 1ffff920001ba190 R15: dffffc0000000000
FS: 00007f8ae451a6c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001480 CR3: 0000000023aec000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x9f/0xe0 kernel/locking/spinlock.c:170
__run_hrtimer kernel/time/hrtimer.c:1689 [inline]
__hrtimer_run_queues+0x5ff/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:native_irq_disable arch/x86/include/asm/irqflags.h:40 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:75 [inline]
RIP: 0010:__raw_spin_lock_irq include/linux/spinlock_api_smp.h:126 [inline]
RIP: 0010:_raw_spin_lock_irq+0x6d/0xe0 kernel/locking/spinlock.c:170
Code: 48 b8 f1 f1 f1 f1 00 f3 f3 f3 49 bf 00 00 00 00 00 fc ff df 4b 89 04 3e 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 8b 44 24 20 <fa> a9 00 02 00 00 74 05 e8 46 13 cb f7 bf 01 00 00 00 e8 fc 95 9e
RSP: 0018:ffffc900037afa80 EFLAGS: 00000a06
RAX: 0000000000000a06 RBX: ffff88801ee940c0 RCX: ffff8880202bd940
RDX: 0000000000000002 RSI: 0000000100000000 RDI: ffff88801ee940c0
RBP: ffffc900037afaf8 R08: dffffc0000000000 R09: ffffed1027fd4641
R10: ffffed1027fd4641 R11: 1ffff11027fd4640 R12: ffff8880202bd940
R13: dffffc0000000000 R14: 1ffff920006f5f50 R15: dffffc0000000000
spin_lock_irq include/linux/spinlock.h:389 [inline]
__set_current_blocked+0xe7/0x240 kernel/signal.c:3086
set_current_blocked kernel/signal.c:3072 [inline]
signal_delivered kernel/signal.c:2936 [inline]
signal_setup_done+0x28c/0x440 kernel/signal.c:2947
handle_signal arch/x86/kernel/signal.c:842 [inline]
arch_do_signal_or_restart+0xf2e/0x1300 arch/x86/kernel/signal.c:869
handle_signal_work kernel/entry/common.c:154 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f8ae62fce00
Code: 83 c0 16 83 e0 f7 74 12 50 48 8d 3d 0a 35 08 00 e8 d5 8e f8 ff 0f 1f 44 00 00 c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <83> ff 21 74 0b c3 66 2e 0f 1f 84 00 00 00 00 00 55 53 48 89 f3 48
RSP: 002b:00007f8ae4519b38 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007f8ae652b098 RCX: 00007f8ae62d46c9
RDX: 00007f8ae4519b40 RSI: 00007f8ae4519c70 RDI: 0000000000000021
RBP: 00007f8ae652b090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8ae652b128 R14: 00007fffe9b2dca0 R15: 00007fffe9b2dd88
</TASK>
sched: RT throttling activated