==================================================================
BUG: KCSAN: data-race in find_get_pages_range_tag / xas_clear_mark

write to 0xffff88800aeafd68 of 8 bytes by task 10925 on cpu 0:
 instrument_write syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/instrumented.h:42 [inline]
 __instrument_read_write_bitop syzkaller/managers/upstream-kcsan-gce/kernel/./include/asm-generic/bitops/instrumented-non-atomic.h:79 [inline]
 __test_and_clear_bit syzkaller/managers/upstream-kcsan-gce/kernel/./include/asm-generic/bitops/instrumented-non-atomic.h:109 [inline]
 node_clear_mark syzkaller/managers/upstream-kcsan-gce/kernel/lib/xarray.c:100 [inline]
 xas_clear_mark+0xa1/0x180 syzkaller/managers/upstream-kcsan-gce/kernel/lib/xarray.c:911
 __test_set_page_writeback+0x3c3/0x4d0 syzkaller/managers/upstream-kcsan-gce/kernel/mm/page-writeback.c:2800
 ext4_bio_write_page+0xfe/0xe90 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/page-io.c:450
 mpage_submit_page syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/inode.c:2101 [inline]
 mpage_map_and_submit_buffers syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/inode.c:2349 [inline]
 mpage_map_and_submit_extent syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/inode.c:2488 [inline]
 ext4_writepages+0xec2/0x1e70 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/inode.c:2801
 do_writepages+0x7b/0x150 syzkaller/managers/upstream-kcsan-gce/kernel/mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 syzkaller/managers/upstream-kcsan-gce/kernel/mm/filemap.c:422
 __filemap_fdatawrite syzkaller/managers/upstream-kcsan-gce/kernel/mm/filemap.c:430 [inline]
 filemap_flush+0x1f/0x30 syzkaller/managers/upstream-kcsan-gce/kernel/mm/filemap.c:457
 ext4_alloc_da_blocks+0x4a/0x100 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/inode.c:3165
 ext4_release_file+0x5b/0x1d0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/file.c:142
 __fput+0x24e/0x4e0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/file_table.c:280
 ____fput+0x11/0x20 syzkaller/managers/upstream-kcsan-gce/kernel/fs/file_table.c:313
 task_work_run+0x8e/0x110 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/task_work.c:140
 get_signal+0x149a/0x14e0 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:2554
 arch_do_signal_or_restart+0x2a/0x270 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/kernel/signal.c:811
 handle_signal_work syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x11a/0x1b0 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:302
 do_syscall_64+0x45/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88800aeafd68 of 8 bytes by task 10919 on cpu 1:
 xas_find_chunk syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/xarray.h:1660 [inline]
 xas_next_marked syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/xarray.h:1691 [inline]
 find_get_pages_range_tag+0x35c/0x600 syzkaller/managers/upstream-kcsan-gce/kernel/mm/filemap.c:2107
 pagevec_lookup_range_tag+0x37/0x50 syzkaller/managers/upstream-kcsan-gce/kernel/mm/swap.c:1122
 mpage_prepare_extent_to_map+0x195/0x640 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/inode.c:2578
 ext4_writepages+0x97b/0x1e70 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/inode.c:2799
 do_writepages+0x7b/0x150 syzkaller/managers/upstream-kcsan-gce/kernel/mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 syzkaller/managers/upstream-kcsan-gce/kernel/mm/filemap.c:422
 __filemap_fdatawrite syzkaller/managers/upstream-kcsan-gce/kernel/mm/filemap.c:430 [inline]
 filemap_flush+0x1f/0x30 syzkaller/managers/upstream-kcsan-gce/kernel/mm/filemap.c:457
 ext4_alloc_da_blocks+0x4a/0x100 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/inode.c:3165
 ext4_release_file+0x5b/0x1d0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/file.c:142
 __fput+0x24e/0x4e0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/file_table.c:280
 ____fput+0x11/0x20 syzkaller/managers/upstream-kcsan-gce/kernel/fs/file_table.c:313
 task_work_run+0x8e/0x110 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/task_work.c:140
 tracehook_notify_resume syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x17c/0x1b0 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:302
 do_syscall_64+0x45/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10919 Comm: syz-executor.1 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================