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BUG: KCSAN: data-race in ep_poll_callback / ep_try_send_events

write to 0xffff8881262813e8 of 4 bytes by task 11821 on cpu 0:
 ep_send_events fs/eventpoll.c:1832 [inline]
 ep_try_send_events+0x510/0x730 fs/eventpoll.c:1905
 ep_poll fs/eventpoll.c:1970 [inline]
 do_epoll_wait+0x371/0x950 fs/eventpoll.c:2461
 do_epoll_pwait+0x54/0x150 fs/eventpoll.c:2491
 __do_sys_epoll_pwait fs/eventpoll.c:2504 [inline]
 __se_sys_epoll_pwait fs/eventpoll.c:2498 [inline]
 __x64_sys_epoll_pwait+0x194/0x1c0 fs/eventpoll.c:2498
 x64_sys_call+0x153d/0x3000 arch/x86/include/generated/asm/syscalls_64.h:282
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881262813e8 of 4 bytes by task 11824 on cpu 1:
 ep_poll_callback+0x4a7/0x580 fs/eventpoll.c:1332
 __wake_up_common kernel/sched/wait.c:108 [inline]
 __wake_up_common_lock kernel/sched/wait.c:125 [inline]
 __wake_up_sync_key+0x52/0x80 kernel/sched/wait.c:192
 unix_write_space+0xcf/0x140 net/unix/af_unix.c:605
 sock_wfree+0x149/0x3a0 net/core/sock.c:2693
 unix_destruct_scm+0xcd/0x100 net/unix/af_unix.c:1980
 skb_release_head_state+0x261/0x270 net/core/skbuff.c:1160
 skb_release_all net/core/skbuff.c:1180 [inline]
 __kfree_skb+0x18/0x150 net/core/skbuff.c:1196
 sk_skb_reason_drop+0xbd/0x260 net/core/skbuff.c:1234
 kfree_skb_reason include/linux/skbuff.h:1322 [inline]
 unix_release_sock+0x62e/0x750 net/unix/af_unix.c:726
 unix_release+0x58/0x80 net/unix/af_unix.c:1184
 __sock_release net/socket.c:662 [inline]
 sock_close+0x6b/0x150 net/socket.c:1455
 __fput+0x29b/0x650 fs/file_table.c:468
 fput_close_sync+0xad/0x190 fs/file_table.c:573
 __do_sys_close fs/open.c:1573 [inline]
 __se_sys_close fs/open.c:1558 [inline]
 __x64_sys_close+0x55/0xf0 fs/open.c:1558
 x64_sys_call+0x2c25/0x3000 arch/x86/include/generated/asm/syscalls_64.h:4
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xe000201d -> 0xe0000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11824 Comm: syz.0.1858 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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