rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=7da4/1/0x4000000000000000 softirq=245590/245626 fqs=6 rcu: (detected by 1, t=10505 jiffies, g=202057, q=1276 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 22502 Comm: syz.6.8409 Not tainted 6.16.0-syzkaller-12256-g561c80369df0 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:__sanitizer_cov_trace_pc+0x66/0x70 kernel/kcov.c:235 Code: 82 18 16 00 00 83 f8 02 75 20 48 8b 8a 20 16 00 00 8b 92 1c 16 00 00 48 8b 01 48 83 c0 01 48 39 d0 73 07 48 89 01 48 89 34 c1 55 b1 da 09 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90000007d88 EFLAGS: 00000046 RAX: 0000000080010002 RBX: ffff88805a7ff340 RCX: 1ffff11004c67926 RDX: ffff888052682440 RSI: ffffffff89a74eaa RDI: 0000000000000005 RBP: ffff88802633c800 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000002 R14: 0000000000000000 R15: ffff888056927800 FS: 00007fd83c1cd6c0(0000) GS:ffff8881246bd000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00002000000ae030 CR3: 0000000060a52000 CR4: 00000000003526f0 DR0: 000000000000004b DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: advance_sched+0x3ea/0xc80 net/sched/sch_taprio.c:966 __run_hrtimer kernel/time/hrtimer.c:1761 [inline] __hrtimer_run_queues+0x202/0xad0 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x10b/0x3f0 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194 Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 46 ca 01 f6 48 89 df e8 2e 1e 02 f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 01 00 00 00 e8 a5 1b f2 f5 65 8b 05 1e 38 40 08 85 c0 74 16 5b RSP: 0018:ffffc90003acf770 EFLAGS: 00000246 RAX: 0000000000000002 RBX: ffff88806637c500 RCX: 0000000000000006 RDX: 0000000000000000 RSI: ffffffff8de4f125 RDI: ffffffff8c162500 RBP: 0000000000000246 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff90ab3597 R11: 0000000000000000 R12: ffff888043049280 R13: 0000000000000246 R14: ffff88806637c4e8 R15: ffffc90003acf8f8 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] __skb_try_recv_datagram+0x172/0x4f0 net/core/datagram.c:267 __unix_dgram_recvmsg+0x1bc/0xc30 net/unix/af_unix.c:2601 unix_dgram_recvmsg+0xd0/0x110 net/unix/af_unix.c:2700 sock_recvmsg_nosec net/socket.c:1065 [inline] ____sys_recvmsg+0x5f6/0x6b0 net/socket.c:2832 ___sys_recvmsg+0x114/0x1a0 net/socket.c:2876 do_recvmmsg+0x2fe/0x750 net/socket.c:2971 __sys_recvmmsg net/socket.c:3045 [inline] __do_sys_recvmmsg net/socket.c:3068 [inline] __se_sys_recvmmsg net/socket.c:3061 [inline] __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3061 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd83df8ebe9 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:00007fd83c1cd038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007fd83e1b6090 RCX: 00007fd83df8ebe9 RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000004 RBP: 00007fd83e011e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd83e1b6128 R14: 00007fd83e1b6090 R15: 00007ffd591d3418 rcu: rcu_preempt kthread starved for 9295 jiffies! g202057 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:27144 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7058 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 4122 Comm: syz-executor Not tainted 6.16.0-syzkaller-12256-g561c80369df0 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xdfd/0x1600 kernel/smp.c:877 Code: 57 48 8b 54 24 10 4c 89 74 24 10 49 89 d5 48 89 d5 48 89 54 24 18 49 c1 ed 03 83 e5 07 4d 01 e5 83 c5 03 e8 05 05 0c 00 f3 90 <41> 0f b6 45 00 40 38 c5 7c 08 84 c0 0f 85 e0 05 00 00 8b 43 08 31 RSP: 0018:ffffc900118b7708 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b8442000 RCX: ffffffff81af8e41 RDX: ffff88803a88c880 RSI: ffffffff81af8e1b RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: dffffc0000000000 R13: ffffed1017088401 R14: 0000000000000001 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881247bd000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe55cf283fd CR3: 0000000053aaf000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1044 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x4a0/0x17a0 arch/x86/mm/tlb.c:1451 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:490 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:480 [inline] tlb_flush_mmu mm/mmu_gather.c:403 [inline] tlb_finish_mmu+0x3c9/0x7c0 mm/mmu_gather.c:497 exit_mmap+0x403/0xb90 mm/mmap.c:1293 __mmput+0x12a/0x410 kernel/fork.c:1129 mmput+0x62/0x70 kernel/fork.c:1152 exit_mm kernel/exit.c:582 [inline] do_exit+0x7c7/0x2bf0 kernel/exit.c:949 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102 get_signal+0x2673/0x26d0 kernel/signal.c:3034 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x84/0x110 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f30b8f84e13 Code: Unable to access opcode bytes at 0x7f30b8f84de9. RSP: 002b:00007ffe949a3608 EFLAGS: 00000202 ORIG_RAX: 000000000000003d RAX: fffffffffffffe00 RBX: 000000000000102c RCX: 00007f30b8f84e13 RDX: 0000000040000000 RSI: 00007ffe949a361c RDI: 00000000ffffffff RBP: 00007ffe949a361c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008 R13: 0000000000000003 R14: 0000000000000009 R15: 0000000000000000