Re: [PATCH] mm/hugetlb: avoid corrupting page->mapping in hugetlb_mcopy_atomic_pte

[Andrew Morton]

On Thu, 14 Jul 2022 17:59:53 +0800 Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote:

> On 2022/7/14 1:23, Andrew Morton wrote:
> > On Tue, 12 Jul 2022 21:05:42 +0800 Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote:
> > 
> >> In MCOPY_ATOMIC_CONTINUE case with a non-shared VMA, pages in the page
> >> cache are installed in the ptes. But hugepage_add_new_anon_rmap is called
> >> for them mistakenly because they're not vm_shared. This will corrupt the
> >> page->mapping used by page cache code.
> > 
> > Well that sounds bad.  And theories on why this has gone unnoticed for
> > over a year?  I assume this doesn't have coverage in our selftests?
> 
> As discussed in another thread, when minor fault handling is proposed, only
> VM_SHARED vma is expected to be supported

So...  do we feel that this fix should be backported?  And if so, is
there a suitable commit for the Fixes:?