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

read-write to 0xffff88811efaad90 of 8 bytes by task 30725 on cpu 1:
 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:893 [inline]
 __xa_set_mark+0xea/0x1c0 lib/xarray.c:2076
 __folio_mark_dirty+0x3b8/0x4e0 mm/page-writeback.c:2767
 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:2266
 ext4_da_do_write_end fs/ext4/inode.c:3017 [inline]
 ext4_da_write_end+0x20a/0x810 fs/ext4/inode.c:3092
 generic_perform_write+0x31e/0x4b0 mm/filemap.c:4123
 ext4_buffered_write_iter+0x1ed/0x3c0 fs/ext4/file.c:299
 ext4_file_write_iter+0x3b2/0xf80 include/linux/fs.h:-1
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x79b/0x950 fs/read_write.c:684
 ksys_pwrite64 fs/read_write.c:791 [inline]
 __do_sys_pwrite64 fs/read_write.c:799 [inline]
 __se_sys_pwrite64 fs/read_write.c:796 [inline]
 __x64_sys_pwrite64+0xfb/0x150 fs/read_write.c:796
 x64_sys_call+0xab9/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:19
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811efaad90 of 8 bytes by task 22929 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1746 [inline]
 xas_find_marked+0x21d/0x660 lib/xarray.c:1510
 find_get_entry+0x5d/0x370 mm/filemap.c:2027
 filemap_get_folios_tag+0x13e/0x220 mm/filemap.c:2294
 mpage_prepare_extent_to_map+0x332/0xb80 fs/ext4/inode.c:2452
 ext4_do_writepages+0xa3b/0x21d0 fs/ext4/inode.c:2736
 ext4_writepages+0x183/0x320 fs/ext4/inode.c:2828
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2656
 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x458/0xa10 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:2047
 wb_writeback+0x276/0x650 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+0x510/0x960 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x52c/0x710 kernel/workqueue.c:3400
 kthread+0x4b7/0x540 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x007fffffffffffff -> 0x01ffffffffffffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 22929 Comm: kworker/u8:16 Not tainted 6.15.0-rc1-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:8)
==================================================================
EXT4-fs error (device loop8): ext4_validate_block_bitmap:441: comm kworker/u8:16: bg 0: block 345: padding at end of block bitmap is not set
EXT4-fs (loop8): Delayed block allocation failed for inode 15 at logical offset 16 with max blocks 944 with error 117
EXT4-fs (loop8): This should not happen!! Data will be lost

IPVS: Schedule: port zero only supported in persistent services, check your ipvs configuration