linux-kernel - Re: [PATCH] mm/hugetlb: avoid corrupting page->mapping in hugetlb_mcopy_atomic

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Message-ID: <0dcf8902-b14a-860a-cb66-46e57b6d14a9@huawei.com>
Date:   Mon, 18 Jul 2022 10:25:25 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Peter Xu <peterx@...hat.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>
CC:     <mike.kravetz@...cle.com>, <songmuchun@...edance.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/hugetlb: avoid corrupting page->mapping in
 hugetlb_mcopy_atomic_pte

On 2022/7/17 7:06, Andrew Morton wrote:
> On Thu, 14 Jul 2022 17:59:53 +0800 Miaohe Lin <linmiaohe@...wei.com> wrote:
> 
>> On 2022/7/14 1:23, Andrew Morton wrote:
>>> On Tue, 12 Jul 2022 21:05:42 +0800 Miaohe Lin <linmiaohe@...wei.com> 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:?

I tend to backport this fix. And I think the Fixes tag in this patch should be suitable,
i.e. Fixes: f619147104c8 ("userfaultfd: add UFFDIO_CONTINUE ioctl").

Thanks.

> .
>