Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Subject: Re: [PATCH] mm/hugetlb: avoid corrupting page->mapping in
 hugetlb_mcopy_atomic_pte
To:     Andrew Morton <akpm@linux-foundation.org>,
        Peter Xu <peterx@redhat.com>,
        Axel Rasmussen <axelrasmussen@google.com>
CC:     <mike.kravetz@oracle.com>, <songmuchun@bytedance.com>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
References: <20220712130542.18836-1-linmiaohe@huawei.com>
 <20220713102357.8328614813db01b569650ffd@linux-foundation.org>
 <a47922cf-eb30-1ad9-fc96-1896254564ef@huawei.com>
 <20220716160629.d065828c84ad2423c10f7733@linux-foundation.org>
From:   Miaohe Lin <linmiaohe@huawei.com>
Message-ID: <0dcf8902-b14a-860a-cb66-46e57b6d14a9@huawei.com>
Date:   Mon, 18 Jul 2022 10:25:25 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.6.0
MIME-Version: 1.0
In-Reply-To: <20220716160629.d065828c84ad2423c10f7733@linux-foundation.org>
Content-Type: text/plain; charset="utf-8"
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

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

> .
>