Please, fix syzbot crash: kernel BUG in filemap_unaccount_folio

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@syzkaller.appspotmail.com Reported-by: syzbot+17a207d226b8a5fb0fd9@syzkaller.appspotmail.com