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

write to 0xffff8880b742e964 of 4 bytes by task 12123 on cpu 1:
 xa_mark_set lib/xarray.c:68 [inline]
 xas_set_mark lib/xarray.c:885 [inline]
 xas_set_mark+0x14d/0x160 lib/xarray.c:869
 __xa_set_mark+0xd3/0x100 lib/xarray.c:1699
 __set_page_dirty+0x152/0x270 fs/buffer.c:624
 __set_page_dirty_buffers+0x1cf/0x280 fs/buffer.c:683
 ext4_set_page_dirty+0xc0/0x190 fs/ext4/inode.c:3563
 set_page_dirty+0x126/0x2b0 mm/page-writeback.c:2572
 fault_dirty_shared_page+0x72/0x1b0 mm/memory.c:2306
 wp_page_shared mm/memory.c:2619 [inline]
 do_wp_page+0xc5f/0xeb0 mm/memory.c:2715
 handle_pte_fault mm/memory.c:3961 [inline]
 __handle_mm_fault+0x1d16/0x2e00 mm/memory.c:4075
 handle_mm_fault+0x21b/0x530 mm/memory.c:4112
 do_user_addr_fault arch/x86/mm/fault.c:1441 [inline]
 __do_page_fault+0x456/0x8d0 arch/x86/mm/fault.c:1506
 do_page_fault+0x38/0x194 arch/x86/mm/fault.c:1530
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1203

read to 0xffff8880b742e964 of 4 bytes by task 21 on cpu 0:
 mapping_tagged include/linux/fs.h:521 [inline]
 requeue_inode fs/fs-writeback.c:1401 [inline]
 writeback_sb_inodes+0x6e3/0xa50 fs/fs-writeback.c:1743
 wb_writeback+0x1f9/0x6a0 fs/fs-writeback.c:1892
 wb_do_writeback fs/fs-writeback.c:2037 [inline]
 wb_workfn+0x22e/0x970 fs/fs-writeback.c:2078
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2264
 worker_thread+0xa0/0x800 kernel/workqueue.c:2410
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21 Comm: kworker/u4:1 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn (flush-8:0)
==================================================================