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Subject: Re: [PATCH 1/4] hugetlbfs: add arch_hugetlb_valid_size
To:     Will Deacon <will@kernel.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
        linux-s390@vger.kernel.org, sparclinux@vger.kernel.org,
        linux-doc@vger.kernel.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        "David S.Miller" <davem@davemloft.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Longpeng <longpeng2@huawei.com>,
        Andrew Morton <akpm@linux-foundation.org>
References: <20200318220634.32100-1-mike.kravetz@oracle.com>
 <20200318220634.32100-2-mike.kravetz@oracle.com>
 <20200318220954.GD8477@willie-the-truck>
From:   Mike Kravetz <mike.kravetz@oracle.com>
Message-ID: <43735ae0-f5f6-1e7b-2d0f-a46f9af1627e@oracle.com>
Date:   Wed, 18 Mar 2020 15:38:53 -0700
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On 3/18/20 3:09 PM, Will Deacon wrote:
> On Wed, Mar 18, 2020 at 03:06:31PM -0700, Mike Kravetz wrote:
>> The architecture independent routine hugetlb_default_setup sets up
>> the default huge pages size.  It has no way to verify if the passed
>> value is valid, so it accepts it and attempts to validate at a later
>> time.  This requires undocumented cooperation between the arch specific
>> and arch independent code.
>>
>> For architectures that support more than one huge page size, provide
>> a routine arch_hugetlb_valid_size to validate a huge page size.
>> hugetlb_default_setup can use this to validate passed values.
>>
>> arch_hugetlb_valid_size will also be used in a subsequent patch to
>> move processing of the "hugepagesz=" in arch specific code to a common
>> routine in arch independent code.
>>
>> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
>> ---
>>  arch/arm64/include/asm/hugetlb.h   |  2 ++
>>  arch/arm64/mm/hugetlbpage.c        | 19 ++++++++++++++-----
>>  arch/powerpc/include/asm/hugetlb.h |  3 +++
>>  arch/powerpc/mm/hugetlbpage.c      | 20 +++++++++++++-------
>>  arch/riscv/include/asm/hugetlb.h   |  3 +++
>>  arch/riscv/mm/hugetlbpage.c        | 28 ++++++++++++++++++----------
>>  arch/s390/include/asm/hugetlb.h    |  3 +++
>>  arch/s390/mm/hugetlbpage.c         | 18 +++++++++++++-----
>>  arch/sparc/include/asm/hugetlb.h   |  3 +++
>>  arch/sparc/mm/init_64.c            | 23 ++++++++++++++++-------
>>  arch/x86/include/asm/hugetlb.h     |  3 +++
>>  arch/x86/mm/hugetlbpage.c          | 21 +++++++++++++++------
>>  include/linux/hugetlb.h            |  7 +++++++
>>  mm/hugetlb.c                       | 16 +++++++++++++---
>>  14 files changed, 126 insertions(+), 43 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
>> index 2eb6c234d594..3248f35213ee 100644
>> --- a/arch/arm64/include/asm/hugetlb.h
>> +++ b/arch/arm64/include/asm/hugetlb.h
<snip>
>> +
>> +static __init int setup_hugepagesz(char *opt)
>> +{
>> +	unsigned long long ps = memparse(opt, &opt);
>> +
>> +	if arch_hugetlb_valid_size(ps)) {
> 
> Please compile your changes if you're touching multiple architectures. You
> can get cross-compiler binaries from:
> 

My apologies.  I only cross compiled the result of the series on each
architecture.  The above code is obviously bad.

-- 
Mike Kravetz