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BUG: KCSAN: data-race in find_get_pages_range_tag / xas_init_marks

write to 0xffff88806b493468 of 8 bytes by task 10388 on cpu 0:
 instrument_write include/linux/instrumented.h:42 [inline]
 __test_and_clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:85 [inline]
 node_clear_mark lib/xarray.c:100 [inline]
 xas_clear_mark lib/xarray.c:908 [inline]
 xas_init_marks+0x17e/0x310 lib/xarray.c:941
 xas_store+0x213/0xd00 lib/xarray.c:803
 page_cache_delete_batch mm/filemap.c:337 [inline]
 delete_from_page_cache_batch+0x418/0x850 mm/filemap.c:358
 truncate_inode_pages_range+0x482/0xf70 mm/truncate.c:366
 truncate_inode_pages mm/truncate.c:476 [inline]
 truncate_pagecache+0x4f/0x70 mm/truncate.c:817
 ext4_setattr+0xb05/0xec0 fs/ext4/inode.c:5403
 notify_change+0x7d7/0xa80 fs/attr.c:336
 do_truncate+0xe0/0x120 fs/open.c:64
 handle_truncate fs/namei.c:2909 [inline]
 do_open fs/namei.c:3255 [inline]
 path_openat+0x1a31/0x20a0 fs/namei.c:3368
 do_filp_open+0xbd/0x1d0 fs/namei.c:3395
 do_sys_openat2+0x33b/0x500 fs/open.c:1168
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_creat fs/open.c:1258 [inline]
 __se_sys_creat fs/open.c:1252 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1252
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88806b493468 of 8 bytes by task 10383 on cpu 1:
 xas_find_chunk include/linux/xarray.h:1625 [inline]
 xas_next_marked include/linux/xarray.h:1656 [inline]
 find_get_pages_range_tag+0x30c/0x5b0 mm/filemap.c:1976
 pagevec_lookup_range_tag+0x37/0x50 mm/swap.c:1122
 mpage_prepare_extent_to_map+0x19c/0x650 fs/ext4/inode.c:2558
 ext4_writepages+0x682/0x1ef0 fs/ext4/inode.c:2735
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19b/0x1d0 mm/filemap.c:422
 __filemap_fdatawrite mm/filemap.c:430 [inline]
 filemap_flush+0x1f/0x30 mm/filemap.c:457
 ext4_alloc_da_blocks+0x4c/0x130 fs/ext4/inode.c:3145
 ext4_release_file+0x5b/0x1c0 fs/ext4/file.c:142
 __fput+0x246/0x4d0 fs/file_table.c:281
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:141
 get_signal+0x11cf/0x1650 kernel/signal.c:2561
 arch_do_signal+0x25/0x270 arch/x86/kernel/signal.c:811
 exit_to_user_mode_loop kernel/entry/common.c:136 [inline]
 exit_to_user_mode_prepare+0x124/0x210 kernel/entry/common.c:167
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:242
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10383 Comm: syz-executor.5 Not tainted 5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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