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Subject: Re: [PATCH 2/4] hugetlbfs: move hugepagesz= parsing to arch
 independent code
To:     Mike Kravetz <mike.kravetz@oracle.com>, 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
Cc:     Albert Ou <aou@eecs.berkeley.edu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Ingo Molnar <mingo@redhat.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Paul Mackerras <paulus@samba.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Longpeng <longpeng2@huawei.com>, Will Deacon <will@kernel.org>,
        "David S . Miller" <davem@davemloft.net>
References: <20200318220634.32100-1-mike.kravetz@oracle.com>
 <20200318220634.32100-3-mike.kravetz@oracle.com>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Message-ID: <2ca058dc-47e6-1d08-154b-77d2cbe98e34@c-s.fr>
Date:   Thu, 19 Mar 2020 08:04:21 +0100
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Le 18/03/2020 à 23:06, Mike Kravetz a écrit :
> Now that architectures provide arch_hugetlb_valid_size(), parsing
> of "hugepagesz=" can be done in architecture independent code.
> Create a single routine to handle hugepagesz= parsing and remove
> all arch specific routines.  We can also remove the interface
> hugetlb_bad_size() as this is no longer used outside arch independent
> code.
> 
> This also provides consistent behavior of hugetlbfs command line
> options.  The hugepagesz= option should only be specified once for
> a specific size, but some architectures allow multiple instances.
> This appears to be more of an oversight when code was added by some
> architectures to set up ALL huge pages sizes.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
> ---
>   arch/arm64/mm/hugetlbpage.c   | 15 ---------------
>   arch/powerpc/mm/hugetlbpage.c | 15 ---------------
>   arch/riscv/mm/hugetlbpage.c   | 16 ----------------
>   arch/s390/mm/hugetlbpage.c    | 18 ------------------
>   arch/sparc/mm/init_64.c       | 22 ----------------------
>   arch/x86/mm/hugetlbpage.c     | 16 ----------------
>   include/linux/hugetlb.h       |  1 -
>   mm/hugetlb.c                  | 24 ++++++++++++++++++------
>   8 files changed, 18 insertions(+), 109 deletions(-)
> 

[snip]

> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 2f99359b93af..cd4ec07080fb 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -3149,12 +3149,6 @@ static int __init hugetlb_init(void)
>   }
>   subsys_initcall(hugetlb_init);
>   
> -/* Should be called on processing a hugepagesz=... option */
> -void __init hugetlb_bad_size(void)
> -{
> -	parsed_valid_hugepagesz = false;
> -}
> -
>   void __init hugetlb_add_hstate(unsigned int order)
>   {
>   	struct hstate *h;
> @@ -3224,6 +3218,24 @@ static int __init hugetlb_nrpages_setup(char *s)
>   }
>   __setup("hugepages=", hugetlb_nrpages_setup);
>   
> +static int __init hugepagesz_setup(char *s)
> +{
> +	unsigned long long size;
> +	char *saved_s = s;
> +
> +	size = memparse(s, &s);

You don't use s after that, so you can pass NULL instead of &s and avoid 
the saved_s

> +
> +	if (!arch_hugetlb_valid_size(size)) {
> +		parsed_valid_hugepagesz = false;
> +		pr_err("HugeTLB: unsupported hugepagesz %s\n", saved_s);
> +		return 0;
> +	}
> +
> +	hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
> +	return 1;
> +}
> +__setup("hugepagesz=", hugepagesz_setup);
> +
>   static int __init default_hugepagesz_setup(char *s)
>   {
>   	unsigned long long size;
> 

Christophe