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BUG: KCSAN: data-race in write_cache_pages / write_cache_pages

write to 0xffff8881005b1e78 of 8 bytes by task 2393 on cpu 1:
 write_cache_pages+0x6f3/0x740 mm/page-writeback.c:2527
 do_writepages+0x20f/0x340 mm/page-writeback.c:2558
 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+0x42/0x210 fs/super.c:666
 kill_block_super+0x2a/0x60 fs/super.c:1646
 ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7305
 deactivate_locked_super+0x73/0x1c0 fs/super.c:481
 fc_drop_locked+0x50/0x60 fs/fs_context.c:379
 vfs_get_tree+0x14e/0x1b0 fs/super.c:1777
 do_new_mount+0x203/0x660 fs/namespace.c:3335
 path_mount+0x496/0xb30 fs/namespace.c:3662
 do_mount fs/namespace.c:3675 [inline]
 __do_sys_mount fs/namespace.c:3884 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3861
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3861
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881005b1e78 of 8 bytes by task 7449 on cpu 0:
 write_cache_pages+0x123/0x740 mm/page-writeback.c:2411
 do_writepages+0x20f/0x340 mm/page-writeback.c:2558
 __writeback_single_inode+0x91/0x860 fs/fs-writeback.c:1608
 writeback_sb_inodes+0x514/0xad0 fs/fs-writeback.c:1899
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:1970
 wb_writeback+0x264/0x6e0 fs/fs-writeback.c:2077
 wb_check_background_flush fs/fs-writeback.c:2147 [inline]
 wb_do_writeback fs/fs-writeback.c:2235 [inline]
 wb_workfn+0x67f/0x8d0 fs/fs-writeback.c:2262
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
 worker_thread+0x525/0x730 kernel/workqueue.c:2784
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0x0000000000000000 -> 0x0000000000000003

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7449 Comm: kworker/u4:29 Not tainted 6.6.0-rc7-syzkaller-00195-g2af9b20dbb39 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Workqueue: writeback wb_workfn (flush-7:4)
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