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Date:   Wed, 18 Mar 2020 22:09:54 +0000
From:   Will Deacon <will@kernel.org>
To:     Mike Kravetz <mike.kravetz@oracle.com>
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>
Subject: Re: [PATCH 1/4] hugetlbfs: add arch_hugetlb_valid_size
Message-ID: <20200318220954.GD8477@willie-the-truck>
References: <20200318220634.32100-1-mike.kravetz@oracle.com>
 <20200318220634.32100-2-mike.kravetz@oracle.com>
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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
> @@ -59,6 +59,8 @@ extern void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
>  extern void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
>  				 pte_t *ptep, pte_t pte, unsigned long sz);
>  #define set_huge_swap_pte_at set_huge_swap_pte_at
> +extern bool __init arch_hugetlb_valid_size(unsigned long long size);
> +#define arch_hugetlb_valid_size arch_hugetlb_valid_size
>  
>  #include <asm-generic/hugetlb.h>
>  
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index bbeb6a5a6ba6..da30127086d0 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -462,23 +462,32 @@ static int __init hugetlbpage_init(void)
>  }
>  arch_initcall(hugetlbpage_init);
>  
> -static __init int setup_hugepagesz(char *opt)
> +bool __init arch_hugetlb_valid_size(unsigned long long size)
>  {
> -	unsigned long ps = memparse(opt, &opt);
> -
> -	switch (ps) {
> +	switch (size) {
>  #ifdef CONFIG_ARM64_4K_PAGES
>  	case PUD_SIZE:
>  #endif
>  	case CONT_PMD_SIZE:
>  	case PMD_SIZE:
>  	case CONT_PTE_SIZE:
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
> +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:

https://mirrors.edge.kernel.org/pub/tools/crosstool/
https://toolchains.bootlin.com/

Will