==================================================================
BUG: KCSAN: data-race in ep_insert / ep_poll

write to 0xffff8881259851d8 of 8 bytes by task 7704 on cpu 1:
 __list_add include/linux/list.h:63 [inline]
 __list_add include/linux/list.h:56 [inline]
 list_add_tail include/linux/list.h:93 [inline]
 ep_insert+0xb7d/0xcf0 fs/eventpoll.c:1576
 __do_sys_epoll_ctl fs/eventpoll.c:2217 [inline]
 __se_sys_epoll_ctl fs/eventpoll.c:2103 [inline]
 __x64_sys_epoll_ctl+0x97e/0xa40 fs/eventpoll.c:2103
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881259851d8 of 8 bytes by task 7707 on cpu 0:
 list_empty_careful include/linux/list.h:287 [inline]
 ep_events_available fs/eventpoll.c:380 [inline]
 ep_poll+0x73c/0x900 fs/eventpoll.c:1907
 do_epoll_wait+0x162/0x180 fs/eventpoll.c:2294
 __do_sys_epoll_pwait fs/eventpoll.c:2325 [inline]
 __se_sys_epoll_pwait fs/eventpoll.c:2311 [inline]
 __x64_sys_epoll_pwait+0xcd/0x180 fs/eventpoll.c:2311
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7707 Comm: syz-fuzzer Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 7707 Comm: syz-fuzzer Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x11d/0x181 lib/dump_stack.c:118
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0xd kernel/kcsan/report.c:315
 kcsan_setup_watchpoint+0x3fe/0x460 kernel/kcsan/core.c:423
 check_access kernel/kcsan/core.c:466 [inline]
 __tsan_read8 kernel/kcsan/core.c:596 [inline]
 __tsan_read8+0xc6/0x100 kernel/kcsan/core.c:596
 list_empty_careful include/linux/list.h:287 [inline]
 ep_events_available fs/eventpoll.c:380 [inline]
 ep_poll+0x73c/0x900 fs/eventpoll.c:1907
 do_epoll_wait+0x162/0x180 fs/eventpoll.c:2294
 __do_sys_epoll_pwait fs/eventpoll.c:2325 [inline]
 __se_sys_epoll_pwait fs/eventpoll.c:2311 [inline]
 __x64_sys_epoll_pwait+0xcd/0x180 fs/eventpoll.c:2311
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45b300
Code: 0f 05 89 44 24 20 c3 cc cc cc 8b 7c 24 08 48 8b 74 24 10 8b 54 24 18 44 8b 54 24 1c 49 c7 c0 00 00 00 00 b8 19 01 00 00 0f 05 <89> 44 24 20 c3 cc cc cc cc cc cc cc cc cc cc cc 8b 7c 24 08 48 c7
RSP: 002b:000000c42014b858 EFLAGS: 00000246 ORIG_RAX: 0000000000000119
RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 000000000045b300
RDX: 0000000000000080 RSI: 000000c42014b898 RDI: 0000000000000004
RBP: 000000c42014be98 R08: 0000000000000000 R09: 000000c420001800
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000000040
R13: 0000000000000040 R14: 00000000000000ff R15: 000000000000000f
Kernel Offset: disabled
Rebooting in 86400 seconds..