Date:   Sun, 22 Jan 2023 19:59:27 -0500
From:   Sasha Levin <sashal@kernel.org>
To:     Catalin Marinas <catalin.marinas@arm.com>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Will Deacon <will@kernel.org>,
        kernel test robot <lkp@intel.com>, akpm@linux-foundation.org,
        anshuman.khandual@arm.com, wangkefeng.wang@huawei.com,
        liushixin2@huawei.com, david@redhat.com, tongtiangen@huawei.com,
        yuzhao@google.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH AUTOSEL 5.4 05/16] arm64/mm: Define dummy pud_user_exec()
 when using 2-level page-table
Message-ID: <Y83b7370jLnWbyx9@sashalap>
References: <20230116140520.116257-1-sashal@kernel.org>
 <20230116140520.116257-5-sashal@kernel.org>
 <Y8WX1/q8dSEAPDy0@arm.com>
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On Mon, Jan 16, 2023 at 06:30:47PM +0000, Catalin Marinas wrote:
>On Mon, Jan 16, 2023 at 09:05:08AM -0500, Sasha Levin wrote:
>> From: Will Deacon <will@kernel.org>
>>
>> [ Upstream commit 4e4ff23a35ee3a145fbc8378ecfeaab2d235cddd ]
>>
>> With only two levels of page-table, the generic 'pud_*' macros are
>> implemented using dummy operations in pgtable-nopmd.h. Since commit
>> 730a11f982e6 ("arm64/mm: add pud_user_exec() check in
>> pud_user_accessible_page()"), pud_user_accessible_page() unconditionally
>> calls pud_user_exec(), which is an arm64-specific helper and therefore
>> isn't defined by pgtable-nopmd.h. This results in a build failure for
>> configurations with only two levels of page table:
>>
>>    arch/arm64/include/asm/pgtable.h: In function 'pud_user_accessible_page':
>> >> arch/arm64/include/asm/pgtable.h:870:51: error: implicit declaration of function 'pud_user_exec'; did you mean 'pmd_user_exec'? [-Werror=implicit-function-declaration]
>>      870 |         return pud_leaf(pud) && (pud_user(pud) || pud_user_exec(pud));
>>          |                                                   ^~~~~~~~~~~~~
>>          |                                                   pmd_user_exec
>>
>> Fix the problem by defining pud_user_exec() as pud_user() in this case.
>>
>> Link: https://lore.kernel.org/r/202301080515.z6zEksU4-lkp@intel.com
>> Reported-by: kernel test robot <lkp@intel.com>
>> Signed-off-by: Will Deacon <will@kernel.org>
>> Signed-off-by: Sasha Levin <sashal@kernel.org>
>
>I don't think this patch should be backported to 5.4. It is a fix for a
>commit that went in shortly before this one (730a11f982e6). The latter
>commit does have a Fixes tag but I guess Will thought it's not worth a
>cc stable (and it's up to 5.19 anyway).

Ack, I'll drop it.

-- 
Thanks,
Sasha