==================================================================
BUG: KCSAN: data-race in __filemap_add_folio / file_write_and_wait_range

read-write to 0xffff88812d16fd80 of 8 bytes by task 30849 on cpu 1:
 __filemap_add_folio+0x4e9/0x990 mm/filemap.c:898
 filemap_add_folio+0x6b/0x150 mm/filemap.c:933
 __filemap_get_folio+0x510/0x6d0 mm/filemap.c:1981
 pagecache_get_page+0x26/0x190 mm/folio-compat.c:104
 grab_cache_page_write_begin+0x2a/0x30 mm/folio-compat.c:116
 ext4_da_write_begin+0x2dd/0x5f0 fs/ext4/inode.c:2988
 generic_perform_write+0x1d4/0x3f0 mm/filemap.c:3738
 ext4_buffered_write_iter+0x235/0x3e0 fs/ext4/file.c:270
 ext4_file_write_iter+0x2e3/0x1210
 do_iter_write+0x494/0x750 fs/read_write.c:855
 vfs_iter_write+0x4c/0x70 fs/read_write.c:896
 iter_file_splice_write+0x44a/0x7c0 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:931
 splice_direct_to_actor+0x305/0x620 fs/splice.c:886
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1303 [inline]
 __x64_sys_sendfile64+0xb9/0x150 fs/read_write.c:1303
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88812d16fd80 of 8 bytes by task 30857 on cpu 0:
 mapping_needs_writeback mm/filemap.c:627 [inline]
 file_write_and_wait_range+0x4b/0x170 mm/filemap.c:772
 ext4_sync_file+0x105/0x6d0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2874 [inline]
 ext4_buffered_write_iter+0x398/0x3e0 fs/ext4/file.c:277
 ext4_file_write_iter+0x2e3/0x1210
 do_iter_write+0x494/0x750 fs/read_write.c:855
 vfs_iter_write+0x4c/0x70 fs/read_write.c:896
 iter_file_splice_write+0x44a/0x7c0 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:931
 splice_direct_to_actor+0x305/0x620 fs/splice.c:886
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1303 [inline]
 __x64_sys_sendfile64+0xb9/0x150 fs/read_write.c:1303
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000041 -> 0x0000000000000042

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30857 Comm: syz-executor.4 Tainted: G        W          5.19.0-syzkaller-13725-g2ae08b36c06e-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
==================================================================