syzbot

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BUG: KCSAN: data-race in filemap_fdatawrite_wbc / xas_set_mark

write to 0xffff888100630b6c of 4 bytes by task 6853 on cpu 1:
 xa_mark_set lib/xarray.c:71 [inline]
 xas_set_mark+0x131/0x150 lib/xarray.c:892
 __folio_start_writeback+0x1f1/0x450 mm/page-writeback.c:3061
 __block_write_full_folio+0x506/0x8d0 fs/buffer.c:1887
 block_write_full_folio+0x293/0x2b0
 write_cache_pages+0x62/0x100 mm/page-writeback.c:2569
 blkdev_writepages+0x59/0x90 block/fops.c:429
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2612
 __writeback_single_inode+0x91/0x870 fs/fs-writeback.c:1650
 writeback_sb_inodes+0x4de/0xaa0 fs/fs-writeback.c:1941
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:2012
 wb_writeback+0x264/0x6f0 fs/fs-writeback.c:2119
 wb_check_background_flush fs/fs-writeback.c:2189 [inline]
 wb_do_writeback fs/fs-writeback.c:2277 [inline]
 wb_workfn+0x67f/0x940 fs/fs-writeback.c:2304
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335
 worker_thread+0x526/0x730 kernel/workqueue.c:3416
 kthread+0x1d1/0x210 kernel/kthread.c:388
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff888100630b6c of 4 bytes by task 615 on cpu 0:
 xa_marked include/linux/xarray.h:420 [inline]
 mapping_tagged include/linux/fs.h:500 [inline]
 filemap_fdatawrite_wbc+0x5c/0x100 mm/filemap.c:393
 __filemap_fdatawrite_range mm/filemap.c:430 [inline]
 __filemap_fdatawrite mm/filemap.c:436 [inline]
 filemap_flush+0x61/0x90 mm/filemap.c:463
 sync_blockdev_nowait+0x36/0x50 block/bdev.c:195
 sync_filesystem+0xe3/0x190 fs/sync.c:60
 generic_shutdown_super+0x42/0x210 fs/super.c:620
 kill_block_super+0x2a/0x70 fs/super.c:1675
 ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7327
 deactivate_locked_super+0x7d/0x1c0 fs/super.c:472
 deactivate_super+0x9f/0xb0 fs/super.c:505
 cleanup_mnt+0x272/0x2e0 fs/namespace.c:1267
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1274
 task_work_run+0x13a/0x1a0 kernel/task_work.c:180
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218
 do_syscall_64+0xda/0x1d0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x01000021 -> 0x02000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 615 Comm: syz-executor.1 Tainted: G        W          6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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EXT4-fs (loop1): unmounting filesystem 00000000-0000-0000-0000-000000000000.