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BUG: KCSAN: data-race in filemap_splice_read / generic_write_end

write to 0xffff88810a0a65f8 of 8 bytes by task 14709 on cpu 0:
 i_size_write include/linux/fs.h:901 [inline]
 generic_write_end+0x9f/0x240 fs/buffer.c:2304
 ext4_da_write_end+0x49e/0x700 fs/ext4/inode.c:2988
 generic_perform_write+0x26d/0x410 mm/filemap.c:3934
 ext4_buffered_write_iter+0x1f6/0x370 fs/ext4/file.c:299
 ext4_file_write_iter+0x283/0x1230
 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:739
 do_splice_from fs/splice.c:934 [inline]
 direct_splice_actor+0x8a/0xb0 fs/splice.c:1143
 splice_direct_to_actor+0x31d/0x690 fs/splice.c:1089
 do_splice_direct+0x10d/0x190 fs/splice.c:1195
 do_sendfile+0x3b6/0x9a0 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 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 0xffff88810a0a65f8 of 8 bytes by task 14719 on cpu 1:
 i_size_read include/linux/fs.h:879 [inline]
 filemap_splice_read+0x274/0x810 mm/filemap.c:2937
 ext4_file_splice_read+0x95/0xb0 fs/ext4/file.c:158
 vfs_splice_read fs/splice.c:994 [inline]
 splice_direct_to_actor+0x28c/0x690 fs/splice.c:1070
 do_splice_direct+0x10d/0x190 fs/splice.c:1195
 do_sendfile+0x3b6/0x9a0 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 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: 0x0000000000733000 -> 0x0000000000734000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14719 Comm: syz-executor.5 Not tainted 6.5.0-rc1-syzkaller-00033-geb26cbb1a754 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
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