rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=63425, q=124) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294998878-4294988376), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g63425 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: 17492 Comm: syz-executor.3 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:__mptcp_update_rmem+0x28/0x1f0 net/mptcp/protocol.c:1931 Code: 00 00 41 54 55 53 48 89 fb e8 e4 6e 8d f8 48 8d ab 6c 08 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 ea 48 c1 ea 03 0f b6 14 02 <48> 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 52 01 00 00 44 RSP: 0018:ffffc9000b13f6f8 EFLAGS: 00000a03 RAX: dffffc0000000000 RBX: ffff888044799780 RCX: ffffc90006419000 RDX: 0000000000000000 RSI: ffffffff88e8b26c RDI: ffff888044799780 RBP: ffff888044799fec R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff88e8aaca R11: 0000000000000000 R12: ffff888044799808 R13: ffffc9000b13f828 R14: dffffc0000000000 R15: ffff888044799780 release_sock+0xb4/0x1b0 net/core/sock.c:3204 mptcp_wait_data net/mptcp/protocol.c:1770 [inline] mptcp_recvmsg+0xfd1/0x27b0 net/mptcp/protocol.c:2080 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: 0033:0x7fa645696739 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:00007fa642c0d188 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007fa64579af80 RCX: 00007fa645696739 RDX: 0000000000000002 RSI: 00000000200017c0 RDI: 0000000000000005 RBP: 00007fa6456f0cc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000100 R11: 0000000000000246 R12: 00007fa64579af80 R13: 00007fff163a3dbf R14: 00007fa642c0d300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: 41 54 push %r12 4: 55 push %rbp 5: 53 push %rbx 6: 48 89 fb mov %rdi,%rbx 9: e8 e4 6e 8d f8 callq 0xf88d6ef2 e: 48 8d ab 6c 08 00 00 lea 0x86c(%rbx),%rbp 15: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 1c: fc ff df 1f: 48 89 ea mov %rbp,%rdx 22: 48 c1 ea 03 shr $0x3,%rdx 26: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx * 2a: 48 89 e8 mov %rbp,%rax <-- trapping instruction 2d: 83 e0 07 and $0x7,%eax 30: 83 c0 03 add $0x3,%eax 33: 38 d0 cmp %dl,%al 35: 7c 08 jl 0x3f 37: 84 d2 test %dl,%dl 39: 0f 85 52 01 00 00 jne 0x191 3f: 44 rex.R