rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=7941, q=4) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294958660-4294948157), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10504 jiffies! g7941 f0x2 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:28064 pid: 15 ppid: 2 flags:0x00004000 Call Trace: 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 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4414 Comm: syz.1.18 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:hlock_class kernel/locking/lockdep.c:197 [inline] RIP: 0010:check_wait_context kernel/locking/lockdep.c:4686 [inline] RIP: 0010:__lock_acquire+0x523/0x7c60 kernel/locking/lockdep.c:4962 Code: 81 e3 ff 1f 00 00 41 c1 ed 03 41 81 e5 f8 03 00 00 49 8d bd c0 e0 fb 8f be 08 00 00 00 e8 85 31 60 00 48 0f a3 1d 7d dc 9f 0e <73> 1f 48 8d 04 5b c1 e0 06 48 8d 98 80 5f 94 8f 48 ba 00 00 00 00 RSP: 0018:ffffc90000007760 EFLAGS: 00000057 RAX: 0000000000000001 RBX: 00000000000000a2 RCX: ffffffff815c043b RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8ffbe0d0 RBP: ffffc900000079b0 R08: dffffc0000000000 R09: fffffbfff1ff7c1b R10: fffffbfff1ff7c1b R11: 1ffffffff1ff7c1a R12: ffff88802699e4a0 R13: 0000000000000010 R14: 0000000000000000 R15: ffff88802699e480 FS: 0000555592129500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000058 CR3: 000000005e4e5000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: reacquire_held_locks+0x2f9/0x590 kernel/locking/lockdep.c:5150 __lock_release kernel/locking/lockdep.c:5339 [inline] lock_release+0x31a/0x870 kernel/locking/lockdep.c:5643 rcu_read_unlock include/linux/rcupdate.h:773 [inline] __lock_task_sighand+0x272/0x290 kernel/signal.c:1409 lock_task_sighand include/linux/sched/signal.h:710 [inline] send_sigqueue+0x177/0x620 kernel/signal.c:1975 posix_timer_event kernel/time/posix-timers.c:360 [inline] posix_timer_fn+0x16a/0x3d0 kernel/time/posix-timers.c:386 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x53d/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 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202 Code: f6 ff 0f 1f 00 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 de 9e a9 f7 48 89 df e8 a6 73 aa f7 e8 41 0d cb f7 fb bf 01 00 00 00 76 95 9e f7 65 8b 05 07 93 4f 76 85 c0 74 02 5b c3 e8 b4 9d 4d RSP: 0018:ffffc900038afbc0 EFLAGS: 00000282 RAX: a6ed916e6fc56200 RBX: ffff88801a5b9bc0 RCX: a6ed916e6fc56200 RDX: dffffc0000000000 RSI: ffffffff8a0b1c60 RDI: 0000000000000001 RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed10034b7379 R10: ffffed10034b7379 R11: 1ffff110034b7378 R12: ffff88801a5b9bc0 R13: 0000000000000021 R14: dffffc0000000000 R15: 000000001c000004 spin_unlock_irq include/linux/spinlock.h:414 [inline] get_signal+0x11d6/0x12c0 kernel/signal.c:2903 arch_do_signal_or_restart+0xc1/0x1300 arch/x86/kernel/signal.c:867 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: 0033:0x7f6841347e7b Code: 41 5e c3 0f 1f 40 00 48 8b 44 24 18 48 8b 1c 24 48 8b b0 80 00 00 00 8b 78 08 48 8d 53 30 e8 0c 53 ff ff 48 89 83 88 00 00 00 45 fe ff ff 8b 7c 24 14 48 8d 74 24 40 ba 0f 00 00 00 e8 fd f1 RSP: 002b:00007ffe73e12650 EFLAGS: 00000206 RAX: 0000000000000000 RBX: 00007f68416cefa0 RCX: 00007f68414faf91 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 00007f68414faf91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f68416cefa0 R14: 00007f68416cefa0 R15: 0000000000000004