syzbot suspects this bug was fixed by commit:

commit c3e5ea6ee574ae5e845a40ac8198de1fb63bb3ab
Author: Kirill A. Shutemov [off-list ref]
Date:   Fri Mar 6 06:28:32 2020 +0000

    mm: avoid data corruption on CoW fault into PFN-mapped VMA

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1170c813e00000
start commit:   e31736d9 Merge tag 'nios2-v5.5-rc2' of git://git.kernel.or..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=79f79de2a27d3e3d
dashboard link: https://syzkaller.appspot.com/bug?extid=9301f2f33873407d5b33
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10fd9fb1e00000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: mm: avoid data corruption on CoW fault into PFN-mapped VMA

For information about bisection process see: https://goo.gl/tpsmEJ#bisection