syzbot

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BUG: KCSAN: data-race in __xa_set_mark / xas_find_marked

read-write to 0xffff88813d05c6b8 of 8 bytes by task 28656 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:885 [inline]
 __xa_set_mark+0xdb/0x1b0 lib/xarray.c:1910
 __folio_mark_dirty+0x3c0/0x4e0 mm/page-writeback.c:2670
 mark_buffer_dirty+0x148/0x240 fs/buffer.c:1212
 __block_commit_write fs/buffer.c:2183 [inline]
 block_write_end+0x158/0x2e0 fs/buffer.c:2259
 ext4_da_do_write_end fs/ext4/inode.c:2951 [inline]
 ext4_da_write_end+0x1fc/0x9c0 fs/ext4/inode.c:3023
 generic_perform_write+0x267/0x410 mm/filemap.c:3980
 ext4_buffered_write_iter+0x1f6/0x370 fs/ext4/file.c:299
 ext4_file_write_iter+0xd6/0x1200
 call_write_iter include/linux/fs.h:1956 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4ab/0x7d0 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88813d05c6b8 of 8 bytes by task 3121 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1723 [inline]
 xas_find_marked+0x216/0x660 lib/xarray.c:1354
 find_get_entry+0x5d/0x290 mm/filemap.c:1978
 filemap_get_folios_tag+0x126/0x250 mm/filemap.c:2266
 mpage_prepare_extent_to_map+0x321/0xb70 fs/ext4/inode.c:2388
 ext4_do_writepages+0x6ea/0x2100 fs/ext4/inode.c:2628
 ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2764
 do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
 __writeback_single_inode+0x91/0x860 fs/fs-writeback.c:1603
 writeback_sb_inodes+0x511/0xaa0 fs/fs-writeback.c:1894
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:1965
 wb_writeback+0x264/0x6e0 fs/fs-writeback.c:2072
 wb_check_start_all fs/fs-writeback.c:2198 [inline]
 wb_do_writeback fs/fs-writeback.c:2224 [inline]
 wb_workfn+0x4ea/0x8d0 fs/fs-writeback.c:2257
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
 worker_thread+0x525/0x730 kernel/workqueue.c:2784
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0x00e0000000000000 -> 0x03e0000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3121 Comm: kworker/u4:5 Tainted: G        W          6.6.0-rc2-syzkaller-00414-g8a511e7efc5a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Workqueue: writeback wb_workfn (flush-8:0)
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