==================================================================
BUG: KCSAN: data-race in __xa_set_mark / xas_find_marked

read-write to 0xffff88811a1c0d90 of 8 bytes by task 9023 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:892 [inline]
 __xa_set_mark+0xdb/0x1b0 lib/xarray.c:1943
 __folio_mark_dirty+0x3b5/0x4e0 mm/page-writeback.c:2798
 mark_buffer_dirty+0x134/0x230 fs/buffer.c:1196
 __block_commit_write fs/buffer.c:2189 [inline]
 block_write_end+0x123/0x210 fs/buffer.c:2265
 ext4_da_do_write_end fs/ext4/inode.c:3011 [inline]
 ext4_da_write_end+0x20a/0x810 fs/ext4/inode.c:3086
 generic_perform_write+0x33c/0x4a0 mm/filemap.c:4203
 ext4_buffered_write_iter+0x1ed/0x3c0 fs/ext4/file.c:299
 ext4_file_write_iter+0x383/0xf20
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0x77b/0x920 fs/read_write.c:679
 ksys_pwrite64 fs/read_write.c:786 [inline]
 __do_sys_pwrite64 fs/read_write.c:794 [inline]
 __se_sys_pwrite64 fs/read_write.c:791 [inline]
 __x64_sys_pwrite64+0xf6/0x150 fs/read_write.c:791
 x64_sys_call+0xab0/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:19
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a1c0d90 of 8 bytes by task 5526 on cpu 1:
 xas_find_chunk include/linux/xarray.h:1733 [inline]
 xas_find_marked+0x217/0x650 lib/xarray.c:1377
 find_get_entry+0x54/0x390 mm/filemap.c:2017
 filemap_get_folios_tag+0x136/0x210 mm/filemap.c:2284
 mpage_prepare_extent_to_map+0x329/0xb80 fs/ext4/inode.c:2448
 ext4_do_writepages+0xa20/0x2130 fs/ext4/inode.c:2733
 ext4_writepages+0x159/0x2e0 fs/ext4/inode.c:2824
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2687
 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x461/0xa30 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:2047
 wb_writeback+0x274/0x640 fs/fs-writeback.c:2158
 wb_check_start_all fs/fs-writeback.c:2284 [inline]
 wb_do_writeback fs/fs-writeback.c:2310 [inline]
 wb_workfn+0x4ea/0x940 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4db/0xa20 kernel/workqueue.c:3319
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3400
 kthread+0x4ae/0x520 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x003fffffffffffff -> 0x00ffffffffffffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5526 Comm: kworker/u8:7 Not tainted 6.14.0-rc6-syzkaller-00007-g0b46b049d6ec #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:3)
==================================================================
EXT4-fs error (device loop3): ext4_validate_block_bitmap:441: comm kworker/u8:7: bg 0: block 345: padding at end of block bitmap is not set
EXT4-fs (loop3): Delayed block allocation failed for inode 15 at logical offset 16 with max blocks 2040 with error 117
EXT4-fs (loop3): This should not happen!! Data will be lost

EXT4-fs (loop3): Delayed block allocation failed for inode 15 at logical offset 2056 with max blocks 2048 with error 28
EXT4-fs (loop3): This should not happen!! Data will be lost

EXT4-fs (loop3): Total free blocks count 0
EXT4-fs (loop3): Free/Dirty block details
EXT4-fs (loop3): free_blocks=0
EXT4-fs (loop3): dirty_blocks=2064
EXT4-fs (loop3): Block reservation details