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BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

read-write to 0xffff888106fa0908 of 8 bytes by interrupt 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]
 __xa_clear_mark+0xf5/0x1e0 lib/xarray.c:2100
 __folio_end_writeback+0x177/0x470 mm/page-writeback.c:3022
 folio_end_writeback+0x71/0x3d0 mm/filemap.c:1660
 end_buffer_async_write+0x156/0x1f0 fs/buffer.c:419
 end_bio_bh_io_sync+0x79/0xa0 fs/buffer.c:2776
 bio_endio+0x37b/0x420 block/bio.c:1651
 blk_update_request+0x336/0x730 block/blk-mq.c:989
 blk_mq_end_request+0x26/0x50 block/blk-mq.c:1151
 lo_complete_rq+0x98/0x140 drivers/block/loop.c:314
 blk_complete_reqs block/blk-mq.c:1226 [inline]
 blk_done_softirq+0x77/0xb0 block/blk-mq.c:1231
 handle_softirqs+0xb7/0x290 kernel/softirq.c:579
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:968
 smpboot_thread_fn+0x32b/0x530 kernel/smpboot.c:160
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888106fa0908 of 8 bytes by task 7687 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:2039
 filemap_get_folios_tag+0x13b/0x210 mm/filemap.c:2307
 __filemap_fdatawait_range mm/filemap.c:530 [inline]
 filemap_write_and_wait_range+0x1d3/0x340 mm/filemap.c:700
 filemap_write_and_wait include/linux/pagemap.h:68 [inline]
 sync_blockdev+0x35/0x50 block/bdev.c:260
 loop_set_status+0x122/0x6a0 drivers/block/loop.c:1243
 loop_set_status_old drivers/block/loop.c:1360 [inline]
 lo_ioctl+0x71b/0x12b0 drivers/block/loop.c:1549
 blkdev_ioctl+0x34f/0x440 block/ioctl.c:705
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:584
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:584
 x64_sys_call+0x1816/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:17
 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: 0xffffffffc0000000 -> 0xffffe00000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 7687 Comm: syz.2.1836 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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loop7: detected capacity change from 16384 to 0