==================================================================
BUG: KCSAN: data-race in filemap_write_and_wait_range / xas_set_mark

write to 0xffff888104a7a77c of 4 bytes by task 15759 on cpu 1:
 xa_mark_set lib/xarray.c:69 [inline]
 xas_set_mark+0x11e/0x130 lib/xarray.c:889
 tag_pages_for_writeback+0xad/0x2f0 mm/page-writeback.c:2133
 ext4_writepages+0x6c3/0x1d70 fs/ext4/inode.c:2736
 do_writepages+0x26b/0x3c0 mm/page-writeback.c:2364
 __writeback_single_inode+0x80/0x440 fs/fs-writeback.c:1616
 writeback_sb_inodes+0x563/0xd30 fs/fs-writeback.c:1881
 wb_writeback+0x27d/0x6d0 fs/fs-writeback.c:2053
 wb_do_writeback+0x101/0x530 fs/fs-writeback.c:2196
 wb_workfn+0xc8/0x540 fs/fs-writeback.c:2237
 process_one_work+0x402/0x910 kernel/workqueue.c:2297
 worker_thread+0x636/0xae0 kernel/workqueue.c:2444
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

read to 0xffff888104a7a77c of 4 bytes by task 16843 on cpu 0:
 xa_marked include/linux/xarray.h:418 [inline]
 mapping_tagged include/linux/fs.h:496 [inline]
 filemap_fdatawrite_wbc mm/filemap.c:396 [inline]
 __filemap_fdatawrite_range mm/filemap.c:433 [inline]
 filemap_write_and_wait_range+0x206/0x3c0 mm/filemap.c:704
 __iomap_dio_rw+0x4ca/0x1010 fs/iomap/direct-io.c:540
 iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:649
 ext4_dio_read_iter fs/ext4/file.c:77 [inline]
 ext4_file_read_iter+0x21a/0x290 fs/ext4/file.c:128
 call_read_iter include/linux/fs.h:2157 [inline]
 generic_file_splice_read+0x24f/0x330 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x63e/0xbb0 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1314 [inline]
 __se_sys_sendfile64 fs/read_write.c:1300 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1300
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x02000021 -> 0x04000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16843 Comm: syz-executor.0 Not tainted 5.15.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
EXT4-fs: 478 callbacks suppressed
EXT4-fs (sda1): Delayed block allocation failed for inode 1184 at logical offset 4 with max blocks 1 with error 28
EXT4-fs (sda1): This should not happen!! Data will be lost

EXT4-fs (sda1): Total free blocks count 0
EXT4-fs (sda1): Free/Dirty block details