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BUG: KCSAN: data-race in __writeback_single_inode / xas_set_mark

write to 0xffff888133309dfc of 4 bytes by task 17840 on cpu 1:
 xa_mark_set lib/xarray.c:69 [inline]
 xas_set_mark+0x11e/0x130 lib/xarray.c:889
 __folio_start_writeback+0x210/0x490 mm/page-writeback.c:2868
 set_page_writeback+0x39/0x50 mm/folio-compat.c:77
 __block_write_full_page+0x5cf/0xa10 fs/buffer.c:1804
 block_write_full_page+0x1f0/0x210
 fat_writepage+0x20/0x30 fs/fat/inode.c:199
 __mpage_writepage+0xca8/0x1060 fs/mpage.c:660
 write_cache_pages+0x454/0x7f0 mm/page-writeback.c:2255
 mpage_writepages+0x7f/0x130 fs/mpage.c:712
 fat_writepages+0x20/0x30 fs/fat/inode.c:205
 do_writepages+0x1cb/0x330 mm/page-writeback.c:2364
 filemap_fdatawrite_wbc mm/filemap.c:407 [inline]
 __filemap_fdatawrite_range mm/filemap.c:440 [inline]
 file_write_and_wait_range+0x132/0x1d0 mm/filemap.c:824
 __generic_file_fsync+0x48/0x140 fs/libfs.c:1115
 fat_file_fsync+0x48/0x100 fs/fat/file.c:190
 vfs_fsync_range+0x107/0x120 fs/sync.c:182
 generic_write_sync include/linux/fs.h:2955 [inline]
 generic_file_write_iter+0x103/0x130 mm/filemap.c:3919
 call_write_iter include/linux/fs.h:2162 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_iter_write+0x4c/0x70 fs/read_write.c:892
 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:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888133309dfc of 4 bytes by task 17838 on cpu 0:
 xa_marked include/linux/xarray.h:418 [inline]
 mapping_tagged include/linux/fs.h:493 [inline]
 __writeback_single_inode+0x209/0x4d0 fs/fs-writeback.c:1667
 writeback_single_inode+0x11f/0x3d0 fs/fs-writeback.c:1729
 sync_inode_metadata+0x57/0x80 fs/fs-writeback.c:2749
 __generic_file_fsync+0xf5/0x140 fs/libfs.c:1126
 fat_file_fsync+0x48/0x100 fs/fat/file.c:190
 vfs_fsync_range+0x107/0x120 fs/sync.c:182
 generic_write_sync include/linux/fs.h:2955 [inline]
 generic_file_write_iter+0x103/0x130 mm/filemap.c:3919
 call_write_iter include/linux/fs.h:2162 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_iter_write+0x4c/0x70 fs/read_write.c:892
 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:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0a000021 -> 0x04000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17838 Comm: syz-executor.4 Not tainted 5.16.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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