syzbot

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BUG: KCSAN: data-race in xas_find_marked / xas_set_mark

write to 0xffff88811816f85c of 4 bytes by task 2337 on cpu 0:
 xa_mark_set lib/xarray.c:69 [inline]
 xas_set_mark+0x11e/0x130 lib/xarray.c:894
 __folio_start_writeback+0x2bf/0x5d0 mm/page-writeback.c:2978
 set_page_writeback+0x3d/0xe0 mm/folio-compat.c:56
 __block_write_full_page+0x4f7/0xb10 fs/buffer.c:1802
 block_write_full_page+0xda/0x100
 __mpage_writepage+0xb00/0xda0 fs/mpage.c:629
 write_cache_pages+0x443/0xa30 mm/page-writeback.c:2359
 mpage_writepages+0x6e/0xe0 fs/mpage.c:664
 fat_writepages+0x20/0x30 fs/fat/inode.c:205
 do_writepages+0x1db/0x350 mm/page-writeback.c:2468
 filemap_fdatawrite_wbc+0xd6/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 file_write_and_wait_range+0xd6/0x170 mm/filemap.c:773
 __generic_file_fsync+0x48/0x140 fs/libfs.c:1115
 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:2869 [inline]
 generic_file_write_iter+0x18d/0x1c0 mm/filemap.c:3902
 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 0xffff88811816f85c of 4 bytes by task 2347 on cpu 1:
 xa_marked include/linux/xarray.h:420 [inline]
 xas_find_marked+0x652/0x6a0 lib/xarray.c:1329
 find_get_entry mm/filemap.c:2010 [inline]
 find_get_pages_range_tag+0x103/0x4f0 mm/filemap.c:2284
 pagevec_lookup_range_tag+0x37/0x50 mm/swap.c:1062
 __filemap_fdatawait_range+0xba/0x260 mm/filemap.c:516
 filemap_fdatawait_range+0x21/0xd0 mm/filemap.c:551
 filemap_fdatawait include/linux/pagemap.h:43 [inline]
 __writeback_single_inode+0xe2/0x590 fs/fs-writeback.c:1597
 writeback_single_inode+0x126/0x4f0 fs/fs-writeback.c:1708
 sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2743
 __generic_file_fsync+0xf5/0x140 fs/libfs.c:1126
 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:2869 [inline]
 generic_file_write_iter+0x18d/0x1c0 mm/filemap.c:3902
 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:1317 [inline]
 __se_sys_sendfile64 fs/read_write.c:1303 [inline]
 __x64_sys_sendfile64+0x10c/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: 0x28000021 -> 0x00000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2347 Comm: syz-executor.5 Not tainted 6.0.0-rc7-syzkaller-00029-g3800a713b607-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
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