rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=12425, q=64 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4294959935-4294949434), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g12425 f0x2 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:25528 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x142d/0x4550 kernel/sched/core.c:6558 schedule+0xbf/0x180 kernel/sched/core.c:6634 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965 rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706 rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905 kthread+0x28d/0x320 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 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: 4796 Comm: syz-executor.2 Not tainted 6.1.94-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 RIP: 0010:match_held_lock+0x2/0xb0 kernel/locking/lockdep.c:5107 Code: e8 03 00 75 cf 48 c7 c7 e0 00 ec 8a 48 c7 c6 20 01 ec 8a e8 00 72 c7 f6 0f 0b eb b6 e8 e7 fa ff ff 0f 1f 80 00 00 00 00 55 53 01 00 00 00 48 39 77 10 74 67 48 89 fb 81 7f 20 00 00 10 00 72 RSP: 0018:ffffc900001e0a88 EFLAGS: 00000087 RAX: 000000000000000f RBX: 0000000000000003 RCX: ffffc900001e0b03 RDX: ffff888055cd0ad8 RSI: ffffffff8d12acc0 RDI: ffff888055cd0b58 RBP: ffffc900001e0bc8 R08: dffffc0000000000 R09: fffffbfff1ce7146 R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888055cd0b58 R13: 0000000000000003 R14: 000000000000000f R15: dffffc0000000000 FS: 00007f49568196c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4956818f80 CR3: 0000000020e82000 CR4: 00000000003526e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: find_held_lock kernel/locking/lockdep.c:5152 [inline] __lock_release kernel/locking/lockdep.c:5337 [inline] lock_release+0x264/0xa20 kernel/locking/lockdep.c:5682 rcu_lock_release include/linux/rcupdate.h:355 [inline] rcu_read_unlock include/linux/rcupdate.h:824 [inline] __lock_task_sighand+0x2b0/0x2d0 kernel/signal.c:1415 lock_task_sighand include/linux/sched/signal.h:745 [inline] send_sigqueue+0x1de/0x720 kernel/signal.c:1978 posix_timer_event kernel/time/posix-timers.c:354 [inline] posix_timer_fn+0x186/0x390 kernel/time/posix-timers.c:380 __run_hrtimer kernel/time/hrtimer.c:1686 [inline] __hrtimer_run_queues+0x5e5/0xe50 kernel/time/hrtimer.c:1750 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1812 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1095 [inline] __sysvec_apic_timer_interrupt+0x156/0x580 arch/x86/kernel/apic/apic.c:1112 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1106 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:653 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202 Code: b1 bc f5 ff 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 7e 2f d5 f6 48 89 df e8 e6 6c d6 f6 e8 01 f9 fb f6 fb bf 01 00 00 00 56 05 c9 f6 65 8b 05 47 12 6d 75 85 c0 74 02 5b c3 e8 f4 35 6b RSP: 0018:ffffc90005c97b30 EFLAGS: 00000286 RAX: e23d1239acd2f400 RBX: ffff888054888940 RCX: ffffffff91c95103 RDX: dffffc0000000000 RSI: ffffffff8aec0240 RDI: 0000000000000001 RBP: ffffc90005c97c70 R08: dffffc0000000000 R09: ffffed100a911129 R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff1100a9111bb R13: 000000001c000004 R14: 0000000000000021 R15: ffff888054888dd8 spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x154b/0x17d0 kernel/signal.c:2865 arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f4955a7cf27 Code: 14 25 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 RSP: 002b:00007f4956819178 EFLAGS: 00000246 RAX: 00000000000000ca RBX: 00007f4955bb3f88 RCX: 00007f4955a7cf29 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f4955bb3f88 RBP: 00007f4955bb3f80 R08: 00007f49568196c0 R09: 00007f49568196c0 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4955bb3f8c R13: 000000000000000b R14: 00007ffddd502af0 R15: 00007ffddd502bd8