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BUG: KCSAN: data-race in __delete_from_page_cache / ext4_writepages

write to 0xffff888126a5d838 of 8 bytes by task 4459 on cpu 1:
 page_cache_delete mm/filemap.c:153 [inline]
 __delete_from_page_cache+0x1d8/0x4a0 mm/filemap.c:238
 delete_from_page_cache+0xb7/0x120 mm/filemap.c:273
 truncate_inode_page+0x48/0x70 mm/truncate.c:228
 truncate_inode_pages_range+0x959/0x1120 mm/truncate.c:449
 truncate_inode_pages mm/truncate.c:476 [inline]
 truncate_pagecache+0x60/0x80 mm/truncate.c:817
 ext4_setattr+0xbd6/0x1670 fs/ext4/inode.c:5327
 notify_change+0x7e1/0xaa0 fs/attr.c:337
 do_truncate+0xfb/0x180 fs/open.c:64
 handle_truncate fs/namei.c:3015 [inline]
 do_last fs/namei.c:3426 [inline]
 path_openat+0x13e8/0x3580 fs/namei.c:3537
 do_filp_open+0x11e/0x1b0 fs/namei.c:3567
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 ksys_open include/linux/syscalls.h:1385 [inline]
 __do_sys_creat fs/open.c:1155 [inline]
 __se_sys_creat fs/open.c:1153 [inline]
 __x64_sys_creat+0x45/0x60 fs/open.c:1153
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888126a5d838 of 8 bytes by task 130 on cpu 0:
 ext4_writepages+0x188/0x2500 fs/ext4/inode.c:2638
 do_writepages+0x6b/0x170 mm/page-writeback.c:2344
 __writeback_single_inode+0xaf/0x8e0 fs/fs-writeback.c:1452
 writeback_sb_inodes+0x4ba/0xa50 fs/fs-writeback.c:1716
 __writeback_inodes_wb+0xe8/0x1b0 fs/fs-writeback.c:1785
 wb_writeback+0x557/0x6a0 fs/fs-writeback.c:1894
 wb_check_start_all fs/fs-writeback.c:2018 [inline]
 wb_do_writeback fs/fs-writeback.c:2044 [inline]
 wb_workfn+0x748/0x970 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: 130 Comm: kworker/u4:3 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)
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