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BUG: KCSAN: data-race in filemap_read / filemap_splice_read

write to 0xffff8881031c5990 of 8 bytes by task 31893 on cpu 0:
 filemap_splice_read+0x5be/0x810 mm/filemap.c:2971
 ext4_file_splice_read+0x95/0xb0 fs/ext4/file.c:158
 vfs_splice_read fs/splice.c:996 [inline]
 splice_direct_to_actor+0x28c/0x690 fs/splice.c:1072
 do_splice_direct+0x10d/0x190 fs/splice.c:1197
 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

write to 0xffff8881031c5990 of 8 bytes by task 31892 on cpu 1:
 filemap_read+0x44c/0x670 mm/filemap.c:2713
 generic_file_read_iter+0x78/0x340 mm/filemap.c:2837
 ext4_file_read_iter+0x1d8/0x2a0
 do_iter_read+0x4ac/0x7c0 fs/read_write.c:795
 vfs_readv fs/read_write.c:915 [inline]
 do_preadv+0x159/0x230 fs/read_write.c:1007
 __do_sys_preadv fs/read_write.c:1057 [inline]
 __se_sys_preadv fs/read_write.c:1052 [inline]
 __x64_sys_preadv+0x58/0x60 fs/read_write.c:1052
 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: 0x0000000000173000 -> 0x0000000000174000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 31892 Comm: syz-executor.0 Not tainted 6.5.0-rc7-syzkaller-00018-g89bf6209cad6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
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