rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4251/1:b..l
	(detected by 1, t=10503 jiffies, g=17569, q=14)
task:udevd           state:R  running task     stack:24216 pid: 4251 ppid:  3545 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6777
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:read_word_at_a_time+0x19/0x20 include/asm-generic/rwonce.h:86
Code: ed ff e9 41 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 53 48 89 fb e8 37 d4 a3 ff 48 89 df be 01 00 00 00 e8 1a be ed ff 48 8b 03 <5b> c3 0f 1f 44 00 00 55 41 57 41 56 41 54 53 49 89 fe e8 10 d4 a3
RSP: 0018:ffffc90002f2f678 EFLAGS: 00000256
RAX: 0000000076656475 RBX: ffff888021ab6ab8 RCX: ffffffff81dcb166
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff888021ab6ab8
RBP: ffff888021a82eb0 R08: dffffc0000000000 R09: ffffed1004356d58
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888021ab6ab8
R13: ffff8880695a1125 R14: ffff888021ab6a50 R15: 0000000000000004
 dentry_string_cmp fs/dcache.c:201 [inline]
 dentry_cmp fs/dcache.c:253 [inline]
 __d_lookup_rcu+0x48a/0x740 fs/dcache.c:2350
 lookup_fast+0x15a/0x7b0 fs/namei.c:1586
 walk_component+0x115/0x610 fs/namei.c:1972
 link_path_walk+0x642/0xd90
 path_parentat fs/namei.c:2502 [inline]
 __filename_parentat+0x24c/0x6c0 fs/namei.c:2526
 filename_parentat fs/namei.c:2544 [inline]
 do_renameat2+0x3b7/0x1700 fs/namei.c:4901
 __do_sys_rename fs/namei.c:5031 [inline]
 __se_sys_rename fs/namei.c:5029 [inline]
 __x64_sys_rename+0x82/0x90 fs/namei.c:5029
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f01dfa8b93b
RSP: 002b:00007ffd45b220f8 EFLAGS: 00000206 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f01dfa8b93b
RDX: 0000561b89c449cf RSI: 00007ffd45b22118 RDI: 00007ffd45b22518
RBP: 0000561ee8297b50 R08: 0000000000000006 R09: 41a0f99c670c2268
R10: 000000000000010f R11: 0000000000000206 R12: 0000561ee82af400
R13: 00007ffd45b22118 R14: 00007ffd45b22518 R15: 0000561ee4e4bec8
 </TASK>
rcu: rcu_preempt kthread starved for 10540 jiffies! g17569 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:27064 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 schedule+0x11b/0x1f0 kernel/sched/core.c:6456
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 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
CPU: 1 PID: 7233 Comm: syz.5.734 Not tainted 5.15.178-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1d2/0x240 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x137a/0x14d0 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+0xa38/0x1150 kernel/rcu/tree.c:2619
 update_process_times+0x196/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x386/0x550 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1688 [inline]
 __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1752
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1814
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x13b/0x4b0 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_enabled kernel/locking/lockdep.c:91 [inline]
RIP: 0010:lock_release+0xfd/0x9a0 kernel/locking/lockdep.c:5636
Code: 0f 85 e0 05 00 00 83 3d f4 c6 a7 0c 00 0f 84 3e 05 00 00 65 8b 05 d3 84 9f 7e 85 c0 0f 85 2f 05 00 00 65 48 8b 05 83 7b 9f 7e <48> 89 44 24 18 48 8d 98 ec 0a 00 00 48 89 d8 48 c1 e8 03 42 0f b6
RSP: 0018:ffffc90003dafae0 EFLAGS: 00000246
RAX: ffff888021419dc0 RBX: 0000000000000001 RCX: ffffffff8162f3e8
RDX: 0000000000000000 RSI: ffffffff8af9f2a0 RDI: ffffffff8af9f260
RBP: ffffc90003dafc20 R08: dffffc0000000000 R09: fffffbfff1c150ee
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920007b5f68
R13: ffffffff81b9f6c8 R14: ffffc90003dafcc0 R15: dffffc0000000000
 _copy_from_user+0x28/0x170 lib/usercopy.c:14
 copy_from_user include/linux/uaccess.h:192 [inline]
 restore_sigcontext+0xce/0x710 arch/x86/kernel/signal.c:91
 __do_sys_rt_sigreturn+0x190/0x250 arch/x86/kernel/signal.c:674
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f624ba24fb9
Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25
RSP: 002b:00007f62498f1b40 EFLAGS: 00000206 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f624bca1fa8 RCX: 00007f624ba24fb9
RDX: 00007f62498f1b40 RSI: 00007f62498f1c70 RDI: 0000000000000021
RBP: 00007f624bca1fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007f624bca1fac
R13: 0000000000000000 R14: 00007ffd8b3fe920 R15: 00007ffd8b3fea08
 </TASK>