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BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

read-write to 0xffff88811b0e5908 of 8 bytes by task 4865 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+0x91/0x180 lib/xarray.c:922
 __folio_start_writeback+0x270/0x370 mm/page-writeback.c:3028
 ext4_bio_write_folio+0x5a6/0xa20 fs/ext4/page-io.c:603
 mpage_submit_folio fs/ext4/inode.c:2103 [inline]
 mpage_process_page_bufs+0x4a1/0x620 fs/ext4/inode.c:2214
 mpage_prepare_extent_to_map+0x7d4/0xc50 fs/ext4/inode.c:2753
 ext4_do_writepages+0x6fe/0x2770 fs/ext4/inode.c:2894
 ext4_writepages+0x18f/0x320 fs/ext4/inode.c:3042
 do_writepages+0x1c6/0x310 mm/page-writeback.c:2571
 filemap_writeback mm/filemap.c:388 [inline]
 filemap_fdatawrite_range mm/filemap.c:413 [inline]
 file_write_and_wait_range+0x178/0x2f0 mm/filemap.c:787
 mmb_fsync_noflush+0x48/0x140 fs/buffer.c:645
 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
 ext4_sync_file+0x1f1/0x6b0 fs/ext4/fsync.c:160
 vfs_fsync_range+0xc5/0xe0 fs/sync.c:186
 generic_write_sync include/linux/fs.h:2654 [inline]
 ext4_buffered_write_iter+0x447/0x4c0 fs/ext4/file.c:322
 ext4_file_write_iter+0x380/0xfa0 fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x5a6/0x9f0 fs/read_write.c:688
 ksys_write+0xdc/0x1a0 fs/read_write.c:740
 __do_sys_write fs/read_write.c:751 [inline]
 __se_sys_write fs/read_write.c:748 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:748
 x64_sys_call+0x27e1/0x3020 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b0e5908 of 8 bytes by task 4873 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:2070 [inline]
 filemap_get_folios_tag+0xfa/0x430 mm/filemap.c:2338
 mpage_prepare_extent_to_map+0x328/0xc50 fs/ext4/inode.c:2655
 ext4_do_writepages+0x6fe/0x2770 fs/ext4/inode.c:2894
 ext4_writepages+0x18f/0x320 fs/ext4/inode.c:3042
 do_writepages+0x1c6/0x310 mm/page-writeback.c:2571
 filemap_writeback mm/filemap.c:388 [inline]
 filemap_fdatawrite_range mm/filemap.c:413 [inline]
 filemap_write_and_wait_range+0x166/0x370 mm/filemap.c:685
 filemap_write_and_wait include/linux/pagemap.h:65 [inline]
 ext4_ioctl_setflags fs/ext4/ioctl.c:648 [inline]
 ext4_fileattr_set+0x4e6/0xe40 fs/ext4/ioctl.c:1027
 vfs_fileattr_set+0x666/0x6b0 fs/file_attr.c:301
 ioctl_setflags+0x14b/0x180 fs/file_attr.c:337
 do_vfs_ioctl+0x661/0xe70 fs/ioctl.c:560
 __do_sys_ioctl fs/ioctl.c:595 [inline]
 __se_sys_ioctl+0x82/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1563/0x3020 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x003fffffffffffff -> 0x003ffffffffffffc

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4873 Comm: syz.1.359 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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