kernel warning in send_event

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 09363dc1775f Set up go function pointer table
git tree: https://github.com/akaros/akaros.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=177c555a400000
kernel config: https://syzkaller.appspot.com/x/.config?x=efef8cf2939304d3
dashboard link: https://syzkaller.appspot.com/bug?extid=ab67ae285c93a8d288a7
compiler:

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ab67ae...@syzkaller.appspotmail.com

kernel warning at kern/src/event.c:374, from core 1: [kernel] Null ev_q -
kernel code should check before sending!
Stack Backtrace on Core 1:
#01 [<0xffffffffc200a33c>] in backtrace at src/kdebug.c:220
#02 [<0xffffffffc2009bd4>] in _warn at src/init.c:323
#03 [<0xffffffffc2007752>] in send_event at src/event.c:374
#04 [<0xffffffffc20560d5>] in sys_send_event at src/syscall.c:1439
#05 [<0xffffffffc2059569>] in syscall at src/syscall.c:2455
#06 [<0xffffffffc2059734>] in run_local_syscall at src/syscall.c:2490
#07 [<0xffffffffc2059c69>] in prep_syscalls at src/syscall.c:2510
#08 [<0xffffffffc20ab5fa>] in sysenter_callwrapper at arch/x86/trap.c:854


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[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 09363dc1775f Set up go function pointer table

git tree: https://github.com/akaros/akaros.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=17e02a7a400000

kernel config: https://syzkaller.appspot.com/x/.config?x=efef8cf2939304d3
dashboard link: https://syzkaller.appspot.com/bug?extid=ab67ae285c93a8d288a7
compiler:

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12f78ab6400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1738de0a400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ab67ae...@syzkaller.appspotmail.com

kernel warning at kern/src/event.c:374, from core 0: [kernel] Null ev_q -

kernel code should check before sending!

Stack Backtrace on Core 0: