syzbot

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

write to 0xffff88810777ea18 of 8 bytes by task 8363 on cpu 0:
 __list_add include/linux/list.h:70 [inline]
 list_add include/linux/list.h:86 [inline]
 ep_done_scan+0xab/0x210 fs/eventpoll.c:644
 ep_send_events fs/eventpoll.c:1709 [inline]
 ep_poll fs/eventpoll.c:1792 [inline]
 do_epoll_wait+0x91c/0xf00 fs/eventpoll.c:2220
 do_epoll_pwait fs/eventpoll.c:2254 [inline]
 __do_sys_epoll_pwait fs/eventpoll.c:2267 [inline]
 __se_sys_epoll_pwait+0xfb/0x210 fs/eventpoll.c:2261
 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2261
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810777ea18 of 8 bytes by task 8361 on cpu 1:
 list_empty_careful include/linux/list.h:319 [inline]
 ep_events_available fs/eventpoll.c:374 [inline]
 ep_poll fs/eventpoll.c:1783 [inline]
 do_epoll_wait+0x292/0xf00 fs/eventpoll.c:2220
 do_epoll_pwait fs/eventpoll.c:2254 [inline]
 __do_sys_epoll_pwait fs/eventpoll.c:2267 [inline]
 __se_sys_epoll_pwait+0xfb/0x210 fs/eventpoll.c:2261
 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2261
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8361 Comm: syz-fuzzer Not tainted 5.12.0-rc2-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: 8361 Comm: syz-fuzzer Not tainted 5.12.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x137/0x19d lib/dump_stack.c:120
 panic+0x1e7/0x5fa kernel/panic.c:231
 kcsan_report+0x67b/0x680 kernel/kcsan/report.c:634
 kcsan_setup_watchpoint+0x40b/0x470 kernel/kcsan/core.c:564
 list_empty_careful include/linux/list.h:319 [inline]
 ep_events_available fs/eventpoll.c:374 [inline]
 ep_poll fs/eventpoll.c:1783 [inline]
 do_epoll_wait+0x292/0xf00 fs/eventpoll.c:2220
 do_epoll_pwait fs/eventpoll.c:2254 [inline]
 __do_sys_epoll_pwait fs/eventpoll.c:2267 [inline]
 __se_sys_epoll_pwait+0xfb/0x210 fs/eventpoll.c:2261
 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2261
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x46e380
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 cc cc cc cc cc cc
RSP: 002b:00007ffde65b2360 EFLAGS: 00000246 ORIG_RAX: 0000000000000119
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000046e380
RDX: 0000000000000080 RSI: 00007ffde65b23b0 RDI: 0000000000000003
RBP: 00007ffde65b29b0 R08: 0000000000000000 R09: 000000c00d206b80
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000000fa
R13: 000000000182ae40 R14: 0000000000000002 R15: 0000000000000002
Kernel Offset: disabled
Rebooting in 86400 seconds..