syzbot

==================================================================
BUG: KCSAN: data-race in do_epoll_wait / ep_scan_ready_list

write to 0xffff888120fbe058 of 8 bytes by task 8694 on cpu 0:
 INIT_LIST_HEAD include/linux/list.h:36 [inline]
 list_splice_init include/linux/list.h:483 [inline]
 ep_scan_ready_list+0x105/0x330 fs/eventpoll.c:707
 ep_send_events fs/eventpoll.c:1788 [inline]
 ep_poll fs/eventpoll.c:1944 [inline]
 do_epoll_wait+0x51f/0x870 fs/eventpoll.c:2333
 __do_sys_epoll_pwait fs/eventpoll.c:2364 [inline]
 __se_sys_epoll_pwait fs/eventpoll.c:2350 [inline]
 __x64_sys_epoll_pwait+0x92/0x150 fs/eventpoll.c:2350
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888120fbe058 of 8 bytes by task 8691 on cpu 1:
 list_empty_careful include/linux/list.h:319 [inline]
 ep_events_available fs/eventpoll.c:379 [inline]
 ep_poll fs/eventpoll.c:1858 [inline]
 do_epoll_wait+0x425/0x870 fs/eventpoll.c:2333
 __do_sys_epoll_pwait fs/eventpoll.c:2364 [inline]
 __se_sys_epoll_pwait fs/eventpoll.c:2350 [inline]
 __x64_sys_epoll_pwait+0x92/0x150 fs/eventpoll.c:2350
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8691 Comm: syz-fuzzer Not tainted 5.9.0-rc5-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: 1 PID: 8691 Comm: syz-fuzzer Not tainted 5.9.0-rc5-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+0x10f/0x19d lib/dump_stack.c:118
 panic+0x207/0x64a kernel/panic.c:231
 kcsan_report+0x684/0x690 kernel/kcsan/report.c:630
 kcsan_setup_watchpoint+0x41e/0x4a0 kernel/kcsan/core.c:540
 list_empty_careful include/linux/list.h:319 [inline]
 ep_events_available fs/eventpoll.c:379 [inline]
 ep_poll fs/eventpoll.c:1858 [inline]
 do_epoll_wait+0x425/0x870 fs/eventpoll.c:2333
 __do_sys_epoll_pwait fs/eventpoll.c:2364 [inline]
 __se_sys_epoll_pwait fs/eventpoll.c:2350 [inline]
 __x64_sys_epoll_pwait+0x92/0x150 fs/eventpoll.c:2350
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x469240
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:00007fff781a4930 EFLAGS: 00000246 ORIG_RAX: 0000000000000119
RAX: ffffffffffffffda RBX: 00000000000493b2 RCX: 0000000000469240
RDX: 0000000000000080 RSI: 00007fff781a4980 RDI: 0000000000000003
RBP: 00007fff781a4f80 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000493b2 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000001970020 R14: 0000000000000008 R15: 0000000000000002
Kernel Offset: disabled
Rebooting in 86400 seconds..