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BUG: KCSAN: data-race in file_write_and_wait_range / xas_set_mark

write to 0xffff88812a91979c of 4 bytes by task 19520 on cpu 0:
 xa_mark_set lib/xarray.c:69 [inline]
 xas_set_mark+0x11e/0x130 lib/xarray.c:889
 __folio_start_writeback+0x2c7/0x5f0 mm/page-writeback.c:2856
 set_page_writeback+0x3d/0xe0 mm/folio-compat.c:78
 ext4_bio_write_page+0xfd/0x860 fs/ext4/page-io.c:449
 mpage_submit_page fs/ext4/inode.c:2090 [inline]
 mpage_process_page_bufs+0x315/0x3d0 fs/ext4/inode.c:2204
 mpage_prepare_extent_to_map+0x480/0x8b0 fs/ext4/inode.c:2630
 ext4_writepages+0x5d6/0x1a60 fs/ext4/inode.c:2758
 do_writepages+0x1cb/0x330 mm/page-writeback.c:2352
 filemap_fdatawrite_wbc mm/filemap.c:388 [inline]
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 file_write_and_wait_range+0x134/0x1d0 mm/filemap.c:779
 ext4_sync_file+0xad/0x570 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2761 [inline]
 ext4_buffered_write_iter+0x243/0x290 fs/ext4/file.c:277
 ext4_file_write_iter+0x21a/0xd70
 call_write_iter include/linux/fs.h:2079 [inline]
 do_iter_readv_writev+0x27d/0x320 fs/read_write.c:726
 do_iter_write+0x192/0x5c0 fs/read_write.c:852
 vfs_iter_write+0x4c/0x70 fs/read_write.c:893
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1246
 __do_sys_sendfile64 fs/read_write.c:1305 [inline]
 __se_sys_sendfile64 fs/read_write.c:1297 [inline]
 __x64_sys_sendfile64+0xb9/0x140 fs/read_write.c:1297
 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+0x44/0xae

read to 0xffff88812a91979c of 4 bytes by task 19528 on cpu 1:
 xa_marked include/linux/xarray.h:418 [inline]
 mapping_tagged include/linux/fs.h:487 [inline]
 filemap_fdatawrite_wbc mm/filemap.c:384 [inline]
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 file_write_and_wait_range+0x101/0x1d0 mm/filemap.c:779
 ext4_sync_file+0xad/0x570 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2761 [inline]
 ext4_buffered_write_iter+0x243/0x290 fs/ext4/file.c:277
 ext4_file_write_iter+0x21a/0xd70
 call_write_iter include/linux/fs.h:2079 [inline]
 do_iter_readv_writev+0x27d/0x320 fs/read_write.c:726
 do_iter_write+0x192/0x5c0 fs/read_write.c:852
 vfs_iter_write+0x4c/0x70 fs/read_write.c:893
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1246
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1297 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1297
 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+0x44/0xae

value changed: 0x05000021 -> 0x02000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19528 Comm: syz-executor.2 Tainted: G        W         5.17.0-syzkaller-11138-gf022814633e1-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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