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BUG: KCSAN: data-race in write_cache_pages / write_cache_pages

write to 0xffff888102016690 of 8 bytes by task 3126 on cpu 0:
 write_cache_pages+0x716/0x760 mm/page-writeback.c:2525
 do_writepages+0x212/0x340 mm/page-writeback.c:2556
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:390
 __filemap_fdatawrite_range mm/filemap.c:423 [inline]
 __filemap_fdatawrite mm/filemap.c:429 [inline]
 filemap_flush+0x95/0xc0 mm/filemap.c:456
 sync_blockdev_nowait+0x36/0x50 block/bdev.c:186
 sync_filesystem+0xe0/0x180 fs/sync.c:60
 generic_shutdown_super+0x40/0x260 fs/super.c:473
 kill_block_super+0x4e/0xa0 fs/super.c:1407
 deactivate_locked_super+0x6b/0xd0 fs/super.c:331
 deactivate_super+0x9b/0xb0 fs/super.c:362
 cleanup_mnt+0x272/0x2e0 fs/namespace.c:1177
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1184
 task_work_run+0x123/0x160 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xd1/0xe0 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:297
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff888102016690 of 8 bytes by task 3781 on cpu 1:
 write_cache_pages+0x716/0x760 mm/page-writeback.c:2525
 do_writepages+0x212/0x340 mm/page-writeback.c:2556
 __writeback_single_inode+0x91/0x860 fs/fs-writeback.c:1600
 writeback_sb_inodes+0x515/0xaa0 fs/fs-writeback.c:1891
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:1962
 wb_writeback+0x24d/0x6c0 fs/fs-writeback.c:2067
 wb_check_background_flush fs/fs-writeback.c:2133 [inline]
 wb_do_writeback fs/fs-writeback.c:2221 [inline]
 wb_workfn+0x67f/0x8d0 fs/fs-writeback.c:2248
 process_one_work+0x3e6/0x750 kernel/workqueue.c:2390
 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2537
 kthread+0x1a6/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

value changed: 0x0000000000000000 -> 0x0000000000000009

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3781 Comm: kworker/u4:7 Not tainted 6.3.0-rc6-syzkaller-00016-g0d3eb744aed4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
Workqueue: writeback wb_workfn (flush-7:5)
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