syzbot

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BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

read-write to 0xffff88811f5996b0 of 8 bytes by task 26 on cpu 0:
 instrument_read_write include/linux/instrumented.h:57 [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:100 [inline]
 xas_clear_mark lib/xarray.c:916 [inline]
 __xa_clear_mark+0xfd/0x1e0 lib/xarray.c:1924
 __folio_end_writeback+0x26b/0x580 mm/page-writeback.c:2925
 folio_end_writeback+0x57/0x130 mm/filemap.c:1620
 end_page_writeback+0x3b/0xe0 mm/folio-compat.c:26
 ext4_finish_bio+0x421/0x520 fs/ext4/page-io.c:145
 ext4_release_io_end+0x98/0x200 fs/ext4/page-io.c:160
 ext4_end_io_end fs/ext4/page-io.c:194 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:259 [inline]
 ext4_end_io_rsv_work+0x319/0x3a0 fs/ext4/page-io.c:273
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

read to 0xffff88811f5996b0 of 8 bytes by task 3719 on cpu 1:
 xas_find_chunk include/linux/xarray.h:1704 [inline]
 xas_find_marked+0x22f/0x6a0 lib/xarray.c:1356
 find_get_entry mm/filemap.c:2010 [inline]
 find_get_pages_range_tag+0x103/0x4f0 mm/filemap.c:2284
 pagevec_lookup_range_tag+0x37/0x50 mm/swap.c:1062
 __filemap_fdatawait_range+0xba/0x260 mm/filemap.c:516
 file_write_and_wait_range+0x11e/0x170 mm/filemap.c:777
 ext4_sync_file+0x105/0x6d0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2869 [inline]
 ext4_buffered_write_iter+0x398/0x3e0 fs/ext4/file.c:277
 ext4_file_write_iter+0x2e3/0x1210
 call_write_iter include/linux/fs.h:2187 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x468/0x760 fs/read_write.c:578
 ksys_write+0xe8/0x1a0 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xfffffff000000000 -> 0xfffff80000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3719 Comm: syz-executor.1 Not tainted 6.0.0-rc7-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
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