syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P15779/1:b..l P16887/2:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=99293, q=380 ncpus=2)
task:syz-executor.0  state:R  running task     stack:25008 pid:16887 tgid:16885 ppid:15803  flags:0x00000006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x17e8/0x4a20 kernel/sched/core.c:6745
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:7067
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__seqprop_spinlock_sequence include/linux/seqlock.h:227 [inline]
RIP: 0010:read_seqbegin include/linux/seqlock.h:772 [inline]
RIP: 0010:neigh_hh_output include/net/neighbour.h:496 [inline]
RIP: 0010:neigh_output include/net/neighbour.h:540 [inline]
RIP: 0010:ip_finish_output2+0x904/0x1380 net/ipv4/ip_output.c:235
Code: 8d 01 00 00 e8 2d 5a b0 f7 4d 85 e4 48 bb 00 00 00 00 00 fc ff df 75 07 e8 19 5a b0 f7 eb 06 e8 12 5a b0 f7 fb 41 0f b6 04 1f <84> c0 0f 85 10 02 00 00 45 8b 2e 44 89 ee 83 e6 01 31 ff e8 34 5e
RSP: 0018:ffffc90009eef420 EFLAGS: 00000287
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000040000
RDX: ffffc900136a2000 RSI: 000000000000625b RDI: 000000000000625c
RBP: ffffc90009eef548 R08: ffffffff89e5ccc0 R09: 1ffffffff25f56c7
R10: dffffc0000000000 R11: fffffbfff25f56c8 R12: 0000000000000200
R13: ffffffff89e4cfbc R14: ffff88804c5ea9d0 R15: 1ffff110098bd53a
 ip_local_out net/ipv4/ip_output.c:129 [inline]
 __ip_queue_xmit+0x118c/0x1b70 net/ipv4/ip_output.c:535
 __tcp_transmit_skb+0x2557/0x3b80 net/ipv4/tcp_output.c:1466
 tcp_cleanup_rbuf net/ipv4/tcp.c:1510 [inline]
 tcp_recvmsg_locked+0x1d00/0x2640 net/ipv4/tcp.c:2560
 tcp_recvmsg+0x25d/0x920 net/ipv4/tcp.c:2590
 inet_recvmsg+0x150/0x2d0 net/ipv4/af_inet.c:885
 sock_recvmsg_nosec net/socket.c:1046 [inline]
 sock_recvmsg+0x1ae/0x280 net/socket.c:1068
 __sys_recvfrom+0x256/0x3e0 net/socket.c:2243
 __do_sys_recvfrom net/socket.c:2261 [inline]
 __se_sys_recvfrom net/socket.c:2257 [inline]
 __x64_sys_recvfrom+0xde/0x100 net/socket.c:2257
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbbe787cea9
RSP: 002b:00007fbbe86500c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
RAX: ffffffffffffffda RBX: 00007fbbe79b4050 RCX: 00007fbbe787cea9
RDX: fffffffffffffd0b RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00007fbbe78ebff4 R08: 0000000000000000 R09: fffffffffffffd25
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fbbe79b4050 R15: 00007ffc84133958
 </TASK>
task:syz-executor.4  state:R  running task     stack:19600 pid:15779 tgid:15779 ppid:15773  flags:0x00000006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x17e8/0x4a20 kernel/sched/core.c:6745
 preempt_schedule_common+0x84/0xd0 kernel/sched/core.c:6924
 preempt_schedule+0xe1/0xf0 kernel/sched/core.c:6948
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 copy_pte_range mm/memory.c:1179 [inline]
 copy_pmd_range+0x7aa1/0x84c0 mm/memory.c:1240
 copy_pud_range mm/memory.c:1277 [inline]
 copy_p4d_range mm/memory.c:1301 [inline]
 copy_page_range+0x99f/0xe90 mm/memory.c:1399
 dup_mmap kernel/fork.c:751 [inline]
 dup_mm kernel/fork.c:1688 [inline]
 copy_mm+0x128d/0x2020 kernel/fork.c:1737
 copy_process+0x187a/0x3dc0 kernel/fork.c:2390
 kernel_clone+0x226/0x8f0 kernel/fork.c:2797
 __do_sys_clone kernel/fork.c:2940 [inline]
 __se_sys_clone kernel/fork.c:2924 [inline]
 __x64_sys_clone+0x258/0x2a0 kernel/fork.c:2924
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feb4b079ed3
RSP: 002b:00007ffce8ccff08 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007feb4b079ed3
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000555578535750 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
rcu: rcu_preempt kthread starved for 10247 jiffies! g99293 f0x0 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:26448 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x17e8/0x4a20 kernel/sched/core.c:6745
 __schedule_loop kernel/sched/core.c:6822 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6837
 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2581
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2000
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2202
 kthread+0x2f2/0x390 kernel/kthread.c:389
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:112