FAT-fs (loop4): error, invalid access to FAT (entry 0x00000001)
FAT-fs (loop4): Filesystem has been set read-only
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BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

read-write to 0xffff888107becfe8 of 8 bytes by task 3515 on cpu 1:
 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+0x91/0x180 lib/xarray.c:922
 __folio_start_writeback+0x257/0x350 mm/page-writeback.c:3034
 __block_write_full_folio+0x526/0x8d0 fs/buffer.c:1905
 block_write_full_folio+0x2c1/0x2e0 fs/buffer.c:-1
 blkdev_writepages+0x88/0x100 block/fops.c:485
 do_writepages+0x1b9/0x300 mm/page-writeback.c:2571
 filemap_writeback mm/filemap.c:387 [inline]
 filemap_fdatawrite_range mm/filemap.c:412 [inline]
 filemap_fdatawrite+0x100/0x140 mm/filemap.c:418
 sync_bdevs+0x1a2/0x260 block/bdev.c:1309
 ksys_sync fs/sync.c:105 [inline]
 __ia32_sys_sync+0x81/0xb0 fs/sync.c:111
 x64_sys_call+0x2f3a/0x3020 arch/x86/include/generated/asm/syscalls_64.h:163
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888107becfe8 of 8 bytes by task 3297 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1752 [inline]
 xas_find_marked+0x211/0x650 lib/xarray.c:1510
 find_get_entry mm/filemap.c:2087 [inline]
 filemap_get_folios_tag+0xf7/0x400 mm/filemap.c:2354
 writeback_get_folio mm/page-writeback.c:2428 [inline]
 writeback_iter+0x48f/0x7c0 mm/page-writeback.c:2529
 blkdev_writepages+0x69/0x100 block/fops.c:484
 do_writepages+0x1b9/0x300 mm/page-writeback.c:2571
 filemap_writeback mm/filemap.c:387 [inline]
 filemap_fdatawrite_range mm/filemap.c:412 [inline]
 filemap_write_and_wait_range+0x166/0x370 mm/filemap.c:684
 filemap_write_and_wait include/linux/pagemap.h:65 [inline]
 sync_blockdev+0x35/0x50 block/bdev.c:276
 kill_block_super+0x3c/0x70 fs/super.c:1673
 deactivate_locked_super+0x75/0x1c0 fs/super.c:477
 deactivate_super+0x97/0xa0 fs/super.c:510
 cleanup_mnt+0x2c3/0x340 fs/namespace.c:1317
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1324
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
 exit_to_user_mode_loop+0x1e4/0x8c0 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x23c/0x3c0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000001 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3297 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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