==================================================================
BUG: KCSAN: data-race in __writeback_single_inode / xas_set_mark

write to 0xffff88815c06459c of 4 bytes by task 21828 on cpu 0:
 xa_mark_set lib/xarray.c:69 [inline]
 xas_set_mark+0x11e/0x130 lib/xarray.c:894
 __folio_start_writeback+0x211/0x4a0 mm/page-writeback.c:3091
 set_page_writeback+0x3d/0xe0 mm/folio-compat.c:50
 __block_write_full_page+0x4f7/0xb10 fs/buffer.c:1787
 block_write_full_page+0xda/0x100
 __mpage_writepage+0xb00/0xda0 fs/mpage.c:629
 write_cache_pages+0x443/0xa30 mm/page-writeback.c:2472
 mpage_writepages+0x6e/0xe0 fs/mpage.c:664
 fat_writepages+0x20/0x30 fs/fat/inode.c:200
 do_writepages+0x1db/0x350 mm/page-writeback.c:2581
 filemap_fdatawrite_wbc+0xd6/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 file_write_and_wait_range+0xf2/0x190 mm/filemap.c:777
 __generic_file_fsync+0x48/0x140 fs/libfs.c:1132
 fat_file_fsync+0x48/0x100 fs/fat/file.c:191
 vfs_fsync_range+0x107/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2885 [inline]
 generic_file_write_iter+0x18d/0x1c0 mm/filemap.c:3936
 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 0xffff88815c06459c of 4 bytes by task 21829 on cpu 1:
 xa_marked include/linux/xarray.h:420 [inline]
 mapping_tagged include/linux/fs.h:461 [inline]
 __writeback_single_inode+0x211/0x590 fs/fs-writeback.c:1649
 writeback_single_inode+0x126/0x490 fs/fs-writeback.c:1719
 sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2775
 __generic_file_fsync+0xf5/0x140 fs/libfs.c:1143
 fat_file_fsync+0x48/0x100 fs/fat/file.c:191
 vfs_fsync_range+0x107/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2885 [inline]
 generic_file_write_iter+0x18d/0x1c0 mm/filemap.c:3936
 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: 0x28000021 -> 0x10000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 21829 Comm: syz-executor.5 Tainted: G        W          6.2.0-rc5-syzkaller-00045-g948ef7bb70c4-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
==================================================================
syz-executor.5: attempt to access beyond end of device
loop5: rw=2049, sector=2048, nr_sectors = 4 limit=2048