==================================================================
BUG: KCSAN: data-race in xas_find_marked / xas_init_marks

read-write to 0xffff88810b6ef6c0 of 8 bytes by task 17133 on cpu 0:
 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 mm/filemap.c:142 [inline]
 __filemap_remove_folio+0x1f1/0x300 mm/filemap.c:228
 __remove_mapping+0x390/0x4c0 mm/vmscan.c:788
 remove_mapping+0x22/0x90 mm/vmscan.c:824
 mapping_evict_folio mm/truncate.c:339 [inline]
 mapping_try_invalidate+0x293/0x430 mm/truncate.c:560
 generic_fadvise+0x40b/0x460 mm/fadvise.c:157
 vfs_fadvise mm/fadvise.c:184 [inline]
 ksys_fadvise64_64 mm/fadvise.c:197 [inline]
 __do_sys_fadvise64 mm/fadvise.c:209 [inline]
 __se_sys_fadvise64 mm/fadvise.c:207 [inline]
 __x64_sys_fadvise64+0xcb/0x110 mm/fadvise.c:207
 x64_sys_call+0x242b/0x3020 arch/x86/include/generated/asm/syscalls_64.h:222
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810b6ef6c0 of 8 bytes by task 10730 on cpu 1:
 xas_find_chunk include/linux/xarray.h:1752 [inline]
 xas_find_marked+0x213/0x620 lib/xarray.c:1510
 find_get_entry mm/filemap.c:2064 [inline]
 filemap_get_folios_tag+0xfa/0x510 mm/filemap.c:2332
 mpage_prepare_extent_to_map+0x328/0xc50 fs/ext4/inode.c:2639
 ext4_do_writepages+0x6fe/0x2800 fs/ext4/inode.c:2878
 ext4_writepages+0x18f/0x320 fs/ext4/inode.c:3026
 do_writepages+0x1c6/0x310 mm/page-writeback.c:2598
 __writeback_single_inode+0x80/0x6e0 fs/fs-writeback.c:1750
 writeback_sb_inodes+0x4f4/0xb70 fs/fs-writeback.c:2041
 wb_writeback+0x24e/0x5b0 fs/fs-writeback.c:2227
 wb_do_writeback fs/fs-writeback.c:2374 [inline]
 wb_workfn+0x194/0x960 fs/fs-writeback.c:2414
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0x4cd/0x9d0 kernel/workqueue.c:3358
 worker_thread+0x581/0x770 kernel/workqueue.c:3439
 kthread+0x22a/0x280 kernel/kthread.c:467
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0xfffffffffffffff8 -> 0xffffffffffff8000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 10730 Comm: kworker/u8:30 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Workqueue: writeback wb_workfn (flush-7:2)
==================================================================
EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 514 with max blocks 1 with error 28
EXT4-fs (loop2): This should not happen!! Data will be lost

EXT4-fs (loop2): Total free blocks count 0
EXT4-fs (loop2): Free/Dirty block details
EXT4-fs (loop2): free_blocks=0
EXT4-fs (loop2): dirty_blocks=16
EXT4-fs (loop2): Block reservation details