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BUG: KCSAN: data-race in filemap_splice_read / simple_write_end

write to 0xffff8881004998b0 of 8 bytes by task 8572 on cpu 0:
 i_size_write include/linux/fs.h:932 [inline]
 simple_write_end+0x26c/0x380 fs/libfs.c:881
 generic_perform_write+0x267/0x410 mm/filemap.c:3980
 __generic_file_write_iter+0xa1/0x120 mm/filemap.c:4064
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4090
 do_iter_write+0x4b4/0x7b0 fs/read_write.c:860
 vfs_iter_write+0x56/0x70 fs/read_write.c:901
 iter_file_splice_write+0x462/0x7e0 fs/splice.c:736
 do_splice_from fs/splice.c:933 [inline]
 direct_splice_actor+0x8a/0xb0 fs/splice.c:1142
 splice_direct_to_actor+0x31d/0x690 fs/splice.c:1088
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3b6/0x9a0 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1316 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0xbd/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881004998b0 of 8 bytes by task 8573 on cpu 1:
 i_size_read include/linux/fs.h:910 [inline]
 filemap_splice_read+0x67b/0x7f0 mm/filemap.c:2915
 vfs_splice_read fs/splice.c:993 [inline]
 splice_direct_to_actor+0x28c/0x690 fs/splice.c:1069
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3b6/0x9a0 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1316 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0xbd/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000002f78 -> 0x0000000000002fb0

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8573 Comm: syz-executor.2 Tainted: G        W          6.6.0-rc3-syzkaller-00165-g3b517966c561 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
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