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BUG: KCSAN: data-race in write_cache_pages / write_cache_pages

write to 0xffff888100696650 of 8 bytes by task 3122 on cpu 1:
 write_cache_pages+0x9ea/0xa30 mm/page-writeback.c:2523
 generic_writepages mm/page-writeback.c:2563 [inline]
 do_writepages+0x225/0x350 mm/page-writeback.c:2583
 filemap_fdatawrite_wbc+0xd6/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 __filemap_fdatawrite mm/filemap.c:427 [inline]
 filemap_flush+0x93/0xc0 mm/filemap.c:454
 sync_blockdev_nowait+0x32/0x40 block/bdev.c:186
 sync_filesystem+0xdc/0x180 fs/sync.c:60
 generic_shutdown_super+0x3c/0x240 fs/super.c:474
 kill_block_super+0x4a/0x90 fs/super.c:1386
 deactivate_locked_super+0x6a/0xb0 fs/super.c:332
 deactivate_super+0x85/0x90 fs/super.c:363
 cleanup_mnt+0x267/0x2d0 fs/namespace.c:1291
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1298
 task_work_run+0xde/0x110 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x124/0x130 kernel/entry/common.c:171
 exit_to_user_mode_prepare kernel/entry/common.c:203 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x6a/0x90 kernel/entry/common.c:296
 do_syscall_64+0x37/0x70 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff888100696650 of 8 bytes by task 19502 on cpu 0:
 write_cache_pages+0x9ea/0xa30 mm/page-writeback.c:2523
 generic_writepages mm/page-writeback.c:2563 [inline]
 do_writepages+0x225/0x350 mm/page-writeback.c:2583
 __writeback_single_inode+0x81/0x590 fs/fs-writeback.c:1598
 writeback_sb_inodes+0x4dd/0xa30 fs/fs-writeback.c:1889
 __writeback_inodes_wb+0xa0/0x1b0 fs/fs-writeback.c:1960
 wb_writeback+0x280/0x650 fs/fs-writeback.c:2065
 wb_check_background_flush fs/fs-writeback.c:2131 [inline]
 wb_do_writeback+0x5b3/0x600 fs/fs-writeback.c:2219
 wb_workfn+0x88/0x260 fs/fs-writeback.c:2246
 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:308

value changed: 0x0000000000000000 -> 0x0000000000000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19502 Comm: kworker/u4:40 Not tainted 6.2.0-rc1-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: writeback wb_workfn (flush-7:3)
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