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BUG: KCSAN: data-race in fasync_insert_entry / sock_sendpage

read-write to 0xffff888104b86540 of 4 bytes by task 26036 on cpu 1:
 fasync_insert_entry+0x12c/0x160 fs/fcntl.c:931
 fasync_add_entry fs/fcntl.c:958 [inline]
 fasync_helper+0x59/0xc0 fs/fcntl.c:976
 sock_fasync+0x5c/0xc0 net/socket.c:1390
 setfl fs/fcntl.c:73 [inline]
 do_fcntl+0xb2d/0xd30 fs/fcntl.c:339
 __do_sys_fcntl fs/fcntl.c:453 [inline]
 __se_sys_fcntl+0xc6/0x180 fs/fcntl.c:438
 __x64_sys_fcntl+0x3f/0x50 fs/fcntl.c:438
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888104b86540 of 4 bytes by task 26021 on cpu 0:
 sock_sendpage+0x3a/0x70 net/socket.c:1050
 pipe_to_sendpage+0x128/0x160 fs/splice.c:364
 splice_from_pipe_feed fs/splice.c:418 [inline]
 __splice_from_pipe+0x222/0x4d0 fs/splice.c:562
 splice_from_pipe fs/splice.c:597 [inline]
 generic_splice_sendpage+0x89/0xc0 fs/splice.c:746
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x660 fs/splice.c:891
 do_splice_direct+0xfb/0x180 fs/splice.c:979
 do_sendfile+0x3ad/0x900 fs/read_write.c:1262
 __do_sys_sendfile64 fs/read_write.c:1327 [inline]
 __se_sys_sendfile64 fs/read_write.c:1313 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1313
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000002 -> 0x00042802

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26021 Comm: syz-executor.3 Not tainted 5.19.0-rc6-syzkaller-00111-gb047602d579b-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
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