FAT-fs (loop0): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.
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BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

read-write to 0xffff88811b999228 of 8 bytes by interrupt on cpu 0:
 instrument_read_write include/linux/instrumented.h:56 [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:2103
 __folio_end_writeback+0xe7/0x530 mm/page-writeback.c:2967
 folio_end_writeback_no_dropbehind+0x6d/0x200 mm/filemap.c:1682
 folio_end_writeback+0x72/0x110 mm/filemap.c:1721
 mpage_write_end_io+0x245/0x4c0 fs/mpage.c:64
 bio_endio+0x390/0x570 block/bio.c:1908
 blk_update_request+0x33a/0x710 block/blk-mq.c:1036
 blk_mq_end_request+0x26/0x50 block/blk-mq.c:1167
 lo_complete_rq+0x98/0x130 drivers/block/loop.c:315
 blk_complete_reqs block/blk-mq.c:1242 [inline]
 blk_done_softirq+0x77/0xb0 block/blk-mq.c:1247
 handle_softirqs+0x109/0x310 kernel/softirq.c:669
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:1133
 smpboot_thread_fn+0x372/0x560 kernel/smpboot.c:162
 kthread+0x223/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88811b999228 of 8 bytes by task 6654 on cpu 1:
 xas_find_chunk include/linux/xarray.h:1752 [inline]
 xas_find_marked+0x211/0x650 lib/xarray.c:1513
 find_get_entry mm/filemap.c:2116 [inline]
 filemap_get_folios_tag+0xf7/0x400 mm/filemap.c:2382
 __filemap_fdatawait_range mm/filemap.c:522 [inline]
 filemap_fdatawait_range+0x88/0x1f0 mm/filemap.c:557
 filemap_fdatawait include/linux/pagemap.h:50 [inline]
 __writeback_single_inode+0xd9/0x790 fs/fs-writeback.c:1819
 writeback_single_inode+0x16d/0x410 fs/fs-writeback.c:1947
 write_inode_now+0xea/0x120 fs/fs-writeback.c:3102
 fat_cont_expand+0x2c8/0x330 fs/fat/file.c:293
 fat_fallocate+0x161/0x190 fs/fat/file.c:334
 vfs_fallocate+0x3ac/0x400 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0x7a/0xd0 fs/open.c:365
 x64_sys_call+0x1e1d/0x2550 arch/x86/include/generated/asm/syscalls_64.h:286
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x116/0x380 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffff0000000000 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6654 Comm: syz.0.1403 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026
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