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BUG: KCSAN: data-race in __filemap_add_folio / file_write_and_wait_range

read-write to 0xffff88810b3c2e40 of 8 bytes by task 31820 on cpu 1:
 __filemap_add_folio+0x379/0x6e0 mm/filemap.c:900
 filemap_add_folio+0x6b/0x150 mm/filemap.c:935
 __filemap_get_folio+0x50a/0x6d0 mm/filemap.c:1977
 pagecache_get_page+0x26/0xd0 mm/folio-compat.c:98
 grab_cache_page_write_begin+0x2a/0x30 mm/folio-compat.c:110
 ext4_da_write_begin+0x2dd/0x5f0 fs/ext4/inode.c:3074
 generic_perform_write+0x1d4/0x3f0 mm/filemap.c:3772
 ext4_buffered_write_iter+0x235/0x3e0 fs/ext4/file.c:285
 ext4_file_write_iter+0x2bb/0x11b0
 do_iter_write+0x494/0x750 fs/read_write.c:861
 vfs_iter_write+0x4c/0x70 fs/read_write.c:902
 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:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1309
 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 0xffff88810b3c2e40 of 8 bytes by task 31836 on cpu 0:
 mapping_needs_writeback mm/filemap.c:624 [inline]
 file_write_and_wait_range+0x66/0x190 mm/filemap.c:776
 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:2882 [inline]
 ext4_buffered_write_iter+0x398/0x3e0 fs/ext4/file.c:292
 ext4_file_write_iter+0x2bb/0x11b0
 do_iter_write+0x494/0x750 fs/read_write.c:861
 vfs_iter_write+0x4c/0x70 fs/read_write.c:902
 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:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1309
 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: 0x0000000000001203 -> 0x0000000000001204

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31836 Comm: syz-executor.3 Tainted: G        W          6.1.0-syzkaller-14587-g51094a24b85e-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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