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Subject: Re: [PATCH v2 2/2] arm64/mm: fix incorrect file_map_count for invalid
 pmd/pud
To:     Will Deacon <will@kernel.org>
References: <20221117075602.2904324-1-liushixin2@huawei.com>
 <20221117075602.2904324-3-liushixin2@huawei.com>
 <20221118143414.GG4046@willie-the-truck>
 <10cecbdf-eb06-873d-6b79-bfdb3197d2ec@huawei.com>
 <20221121181636.GD7645@willie-the-truck>
CC:     Catalin Marinas <catalin.marinas@arm.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        "Anshuman Khandual" <anshuman.khandual@arm.com>,
        David Hildenbrand <dhildenb@redhat.com>,
        Rafael Aquini <raquini@redhat.com>,
        Pasha Tatashin <pasha.tatashin@soleen.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
From:   Liu Shixin <liushixin2@huawei.com>
Message-ID: <1f4ef941-6b45-8562-1723-21048a639c18@huawei.com>
Date:   Tue, 22 Nov 2022 09:24:57 +0800
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On 2022/11/22 2:16, Will Deacon wrote:
> On Mon, Nov 21, 2022 at 11:15:49AM +0800, Liu Shixin wrote:
>> On 2022/11/18 22:34, Will Deacon wrote:
>>> On Thu, Nov 17, 2022 at 03:56:02PM +0800, Liu Shixin wrote:
>>>>  static inline bool pud_user_accessible_page(pud_t pud)
>>>>  {
>>>> -	return pud_leaf(pud) && pud_user(pud);
>>>> +	return pud_valid(pud) && pud_leaf(pud) && pud_user(pud);
>>> Not caused by this patch, but why don't we have something like a
>>> pud_user_exec() check here like we do for the pte and pmd levels?
>> As far as I know, there is no user use the user executable pud on arm64, so didn't define pud_user_exec().
> I can believe they don't get exposed to userspace at all, but exposing only
> as non-executable doesn't sound right. So I would have thought that either
> pud_user_accessible_page() would always return false or it would need to
> check for the executable case too.
Thanks for your advice, I will add the check for the executable case too.

>
> Will
> .
>