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BUG: KCSAN: data-race in xas_find_marked / xas_init_marks

read-write to 0xffff88810068f230 of 8 bytes by task 1671 on cpu 1:
 instrument_read_write include/linux/instrumented.h:55 [inline]
 __instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:84 [inline]
 ___test_and_clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:114 [inline]
 node_clear_mark lib/xarray.c:102 [inline]
 xas_clear_mark lib/xarray.c:922 [inline]
 xas_init_marks+0x18a/0x320 lib/xarray.c:955
 xas_store+0x3cf/0xce0 lib/xarray.c:817
 page_cache_delete_batch mm/filemap.c:313 [inline]
 delete_from_page_cache_batch+0x30a/0x6f0 mm/filemap.c:335
 truncate_inode_pages_range+0x1ba/0x780 mm/truncate.c:380
 truncate_pagecache_range+0x83/0xa0 mm/truncate.c:896
 ext4_truncate_page_cache_block_range+0x357/0x370 fs/ext4/inode.c:4346
 ext4_punch_hole+0x1ff/0x770 fs/ext4/inode.c:4427
 ext4_fallocate+0x2d7/0x2f0 fs/ext4/extents.c:4822
 vfs_fallocate+0x3b6/0x400 fs/open.c:342
 ksys_fallocate fs/open.c:366 [inline]
 __do_sys_fallocate fs/open.c:371 [inline]
 __se_sys_fallocate fs/open.c:369 [inline]
 __x64_sys_fallocate+0x7a/0xd0 fs/open.c:369
 x64_sys_call+0x2518/0x3000 arch/x86/include/generated/asm/syscalls_64.h:286
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810068f230 of 8 bytes by task 1659 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1752 [inline]
 xas_find_marked+0x218/0x620 lib/xarray.c:1510
 find_get_entry+0x5d/0x380 mm/filemap.c:2070
 filemap_get_folios_tag+0x13b/0x210 mm/filemap.c:2338
 mpage_prepare_extent_to_map+0x320/0xc00 fs/ext4/inode.c:2637
 ext4_do_writepages+0x708/0x2750 fs/ext4/inode.c:2877
 ext4_writepages+0x176/0x300 fs/ext4/inode.c:3025
 do_writepages+0x1c3/0x310 mm/page-writeback.c:2604
 filemap_fdatawrite_wbc mm/filemap.c:389 [inline]
 __filemap_fdatawrite_range mm/filemap.c:422 [inline]
 file_write_and_wait_range+0x156/0x2c0 mm/filemap.c:797
 generic_buffers_fsync_noflush+0x45/0x120 fs/buffer.c:609
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1ab/0x690 fs/ext4/fsync.c:147
 vfs_fsync_range+0x10a/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:3045 [inline]
 ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:305
 ext4_file_write_iter+0x387/0xf60 fs/ext4/file.c:-1
 do_iter_readv_writev+0x4a1/0x540 fs/read_write.c:-1
 vfs_writev+0x2df/0x8b0 fs/read_write.c:1057
 do_pwritev fs/read_write.c:1153 [inline]
 __do_sys_pwritev2 fs/read_write.c:1211 [inline]
 __se_sys_pwritev2+0xfc/0x1c0 fs/read_write.c:1202
 __x64_sys_pwritev2+0x67/0x80 fs/read_write.c:1202
 x64_sys_call+0x2c59/0x3000 arch/x86/include/generated/asm/syscalls_64.h:329
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffffffffffff80 -> 0xffffffffffff0000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 1659 Comm: syz.8.10306 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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