rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=104309, q=13) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4295017524-4295007022), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g104309 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:28696 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4955 [inline] __schedule+0x940/0x26f0 kernel/sched/core.c:6236 schedule+0xd3/0x270 kernel/sched/core.c:6315 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1955 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2128 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 24503 Comm: syz-executor.2 Not tainted 5.15.0-rc2-next-20210920-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:481 print_other_cpu_stall kernel/rcu/tree_stall.h:586 [inline] check_cpu_stall kernel/rcu/tree_stall.h:729 [inline] rcu_pending kernel/rcu/tree.c:3878 [inline] rcu_sched_clock_irq+0x2125/0x2200 kernel/rcu/tree.c:2597 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1428 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:read_pnet include/net/net_namespace.h:327 [inline] RIP: 0010:sock_net include/net/sock.h:2603 [inline] RIP: 0010:tcp_win_from_space include/net/tcp.h:1401 [inline] RIP: 0010:__mptcp_space net/mptcp/protocol.h:315 [inline] RIP: 0010:mptcp_cleanup_rbuf net/mptcp/protocol.c:489 [inline] RIP: 0010:mptcp_recvmsg+0x7ee/0x27b0 net/mptcp/protocol.c:2027 Code: 00 00 4c 89 e0 48 c1 e8 03 42 0f b6 14 30 4c 89 e0 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 32 1e 00 00 41 8b 87 6c 08 00 00 <49> 8d 7f 30 01 c3 48 89 f8 48 c1 e8 03 44 29 eb 42 80 3c 30 00 0f RSP: 0018:ffffc9000a61f738 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000020000 RCX: ffffffff88e98b97 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88807e859988 RBP: ffff88807e859988 R08: 0000000000000000 R09: ffff88807e85998b R10: ffffed100fd0b331 R11: 0000000000000000 R12: ffff88807e859fec R13: 0000000000000000 R14: dffffc0000000000 R15: ffff88807e859780 inet6_recvmsg+0x11b/0x5e0 net/ipv6/af_inet6.c:659 sock_recvmsg_nosec net/socket.c:944 [inline] ____sys_recvmsg+0x527/0x600 net/socket.c:2626 ___sys_recvmsg+0x127/0x200 net/socket.c:2670 do_recvmmsg+0x24d/0x6d0 net/socket.c:2764 __sys_recvmmsg net/socket.c:2843 [inline] __do_sys_recvmmsg net/socket.c:2866 [inline] __se_sys_recvmmsg net/socket.c:2859 [inline] __x64_sys_recvmmsg+0x20b/0x260 net/socket.c:2859 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fe349bf1739 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fe347168188 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007fe349cf5f80 RCX: 00007fe349bf1739 RDX: 0000000000000002 RSI: 00000000200017c0 RDI: 0000000000000003 RBP: 00007fe349c4bcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000100 R11: 0000000000000246 R12: 00007fe349cf5f80 R13: 00007ffd6215a69f R14: 00007fe347168300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: 4c 89 e0 mov %r12,%rax 5: 48 c1 e8 03 shr $0x3,%rax 9: 42 0f b6 14 30 movzbl (%rax,%r14,1),%edx e: 4c 89 e0 mov %r12,%rax 11: 83 e0 07 and $0x7,%eax 14: 83 c0 03 add $0x3,%eax 17: 38 d0 cmp %dl,%al 19: 7c 08 jl 0x23 1b: 84 d2 test %dl,%dl 1d: 0f 85 32 1e 00 00 jne 0x1e55 23: 41 8b 87 6c 08 00 00 mov 0x86c(%r15),%eax * 2a: 49 8d 7f 30 lea 0x30(%r15),%rdi <-- trapping instruction 2e: 01 c3 add %eax,%ebx 30: 48 89 f8 mov %rdi,%rax 33: 48 c1 e8 03 shr $0x3,%rax 37: 44 29 eb sub %r13d,%ebx 3a: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1) 3f: 0f .byte 0xf