Re: [PATCH v2 1/4] hugetlbfs: add arch_hugetlb_valid_size

From: Peter Xu <peterx@redhat.com>
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,
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	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	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>,
	Christophe Leroy <christophe.leroy@c-s.fr>,
	Mina Almasry <almasrymina@google.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2 1/4] hugetlbfs: add arch_hugetlb_valid_size
Date: Fri, 10 Apr 2020 15:16:13 -0400	[thread overview]
Message-ID: <20200410191613.GD3172@xz-x1> (raw)
In-Reply-To: <20200401183819.20647-2-mike.kravetz@oracle.com>

On Wed, Apr 01, 2020 at 11:38:16AM -0700, Mike Kravetz wrote:
> diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
> index 2eb6c234d594..81606223494f 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
> +bool __init arch_hugetlb_valid_size(unsigned long size);
> +#define arch_hugetlb_valid_size arch_hugetlb_valid_size

Sorry for chimming in late.

Since we're working on removing arch-dependent codes after all.. I'm
thinking whether we can define arch_hugetlb_valid_size() once in the
common header (e.g. linux/hugetlb.h), then in mm/hugetlb.c:

bool __init __attribute((weak)) arch_hugetlb_valid_size(unsigned long size)
{
	return size == HPAGE_SIZE;
}

We can simply redefine arch_hugetlb_valid_size() in arch specific C
files where we want to override the default.  Would that be slightly
cleaner?

Thanks,

-- 
Peter Xu