[lvc-project] Please, fix syzbot crash: kernel BUG in filemap_unaccount_folio

[Andrey Kalachev]

Hi all.

The upstream kernels late than v6.10-rc6 has the patch:

   7d79cd784470 udmabuf: use vmf_insert_pfn and VM_PFNMAP for handling mmap

That patch stop reproducing syzbot crashes [1], [2].
The reproducer code [3] still crash longterm & stable kernel versions v5.4-v6.6.
Here the 7d79cd784470 backports below.
Patch v6.6 just cherry-picked, patch for v5.4-v6.1 has minor change described
in the patch note.

Regards,
AK

[1] https://syzkaller.appspot.com/bug?extid=3d218f7b6c5511a83a79
[2] https://syzkaller.appspot.com/bug?extid=17a207d226b8a5fb0fd9
[3] https://syzkaller.appspot.com/text?tag=ReproC&x=10c0b8c0580000

Reported-by: syzbot+3d218f7b6c5511a83a79 at syzkaller.appspotmail.com
Reported-by: syzbot+17a207d226b8a5fb0fd9 at syzkaller.appspotmail.com