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BUG: KCSAN: data-race in filemap_splice_read / simple_write_end

write to 0xffff888106aa6050 of 8 bytes by task 23178 on cpu 0:
 i_size_write include/linux/fs.h:932 [inline]
 simple_write_end+0x26c/0x380 fs/libfs.c:886
 generic_perform_write+0x267/0x410 mm/filemap.c:3929
 __generic_file_write_iter+0xa1/0x120 mm/filemap.c:4013
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4039
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x48a/0x790 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888106aa6050 of 8 bytes by task 23179 on cpu 1:
 i_size_read include/linux/fs.h:910 [inline]
 filemap_splice_read+0x67b/0x7f0 mm/filemap.c:2856
 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+0x3c4/0x980 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:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000000000001f8 -> 0x0000000000000214

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23179 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-15859-g89cdf9d55601 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
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