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BUG: KCSAN: data-race in __xa_set_mark / xas_find_marked

read-write to 0xffff888107383d88 of 8 bytes by task 19899 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_set_bit include/asm-generic/bitops/instrumented-non-atomic.h:99 [inline]
 node_set_mark lib/xarray.c:95 [inline]
 xas_set_mark lib/xarray.c:893 [inline]
 __xa_set_mark+0xd2/0x1a0 lib/xarray.c:2082
 __folio_mark_dirty+0x384/0x4a0 mm/page-writeback.c:2718
 mark_buffer_dirty+0x11e/0x210 fs/buffer.c:1206
 block_commit_write fs/buffer.c:2218 [inline]
 block_page_mkwrite+0x287/0x3d0 fs/buffer.c:2643
 ext4_page_mkwrite+0x859/0xb90 fs/ext4/inode.c:6704
 do_page_mkwrite mm/memory.c:3488 [inline]
 do_shared_fault mm/memory.c:5774 [inline]
 do_fault mm/memory.c:5836 [inline]
 do_pte_missing mm/memory.c:4361 [inline]
 handle_pte_fault mm/memory.c:6177 [inline]
 __handle_mm_fault mm/memory.c:6318 [inline]
 handle_mm_fault+0x15ce/0x2be0 mm/memory.c:6487
 do_user_addr_fault+0x630/0x1080 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

read to 0xffff888107383d88 of 8 bytes by task 162 on cpu 1:
 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+0x92/0x210 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+0x1c6/0x310 mm/page-writeback.c:2604
 __writeback_single_inode+0x80/0x7c0 fs/fs-writeback.c:1719
 writeback_sb_inodes+0x48f/0xa30 fs/fs-writeback.c:2015
 __writeback_inodes_wb+0x94/0x1a0 fs/fs-writeback.c:2086
 wb_writeback+0x266/0x5c0 fs/fs-writeback.c:2197
 wb_check_start_all fs/fs-writeback.c:2323 [inline]
 wb_do_writeback fs/fs-writeback.c:2349 [inline]
 wb_workfn+0x4c9/0x910 fs/fs-writeback.c:2382
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346
 worker_thread+0x582/0x770 kernel/workqueue.c:3427
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x8000000000000000 -> 0xe000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 162 Comm: kworker/u8:4 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: writeback wb_workfn (flush-8:0)
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