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BUG: KCSAN: data-race in filemap_splice_read / filemap_splice_read

write to 0xffff88812274b990 of 8 bytes by task 10731 on cpu 1:
 filemap_splice_read+0x6cc/0x920 mm/filemap.c:2916
 ext4_file_splice_read+0x95/0xc0 fs/ext4/file.c:158
 do_splice_read fs/splice.c:985 [inline]
 splice_direct_to_actor+0x26c/0x670 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x970 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

write to 0xffff88812274b990 of 8 bytes by task 10735 on cpu 0:
 filemap_splice_read+0x6cc/0x920 mm/filemap.c:2916
 ext4_file_splice_read+0x95/0xc0 fs/ext4/file.c:158
 do_splice_read fs/splice.c:985 [inline]
 splice_direct_to_actor+0x26c/0x670 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x970 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

value changed: 0x00000000003fa000 -> 0x0000000000400000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10735 Comm: syz-executor.2 Tainted: G        W          6.9.0-rc2-syzkaller-00080-gc85af715cac0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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