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From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Robin Murphy <robin.murphy@arm.com>,
	kernel test robot <lkp@intel.com>,
	linux-mm@kvack.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Barry Song <song.bao.hua@hisilicon.com>,
	kbuild-all@lists.01.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH] arm64/hugetlb: Reserve CMA areas for gigantic pages on 16K and 64K configs
Date: Wed, 24 Jun 2020 17:52:07 +0530	[thread overview]
Message-ID: <b10321d4-4999-8e14-ca2c-a490daccac9a@arm.com> (raw)
In-Reply-To: <63be846e-7e61-39f7-e3f3-9a61cb50e44c@arm.com>



On 06/24/2020 03:15 PM, Robin Murphy wrote:
> On 2020-06-24 01:17, Anshuman Khandual wrote:
>>
>>
>> On 06/23/2020 10:10 PM, Robin Murphy wrote:
>>> On 2020-06-23 13:48, Anshuman Khandual wrote:
>>>>
>>>> On 06/23/2020 02:54 PM, kernel test robot wrote:
>>>>>      423        /*
>>>>>      424         * must be done after arm64_numa_init() which calls numa_init() to
>>>>>      425         * initialize node_online_map that gets used in hugetlb_cma_reserve()
>>>>>      426         * while allocating required CMA size across online nodes.
>>>>>      427         */
>>>>>    > 428        arm64_hugetlb_cma_reserve();
>>>>
>>>> Wrapping this call site with CONFIG_HUGETLB_PAGE solves the problem.
>>>
>>> ...although it might be nicer to include asm/hugetlb.h directly so that you can pick up the stub definition reliably.
>>
>> Including <asm/hugetlb.h> directly does not solve the problem and
>> <linux/hugetlb.h> is no better. arm64_hugetlb_cma_reserve() needs
>> protection wrt both CMA and HUGETLB_PAGE. Dropped HUGETLB_PAGE
>> assuming it should have been taken care as the stub itself was in
>> <asm/hugetlb.h>, which turns out to be not true.
> 
> Sure, I wasn't suggesting that the implementation of the header itself wouldn't need tweaking - the point I was trying to get at is that it's preferable to have *either* a stub definition in an always-reachable header, *or* inline #ifdefs around the caller. Mixing both such that there are 3 or 4 possible combinations just isn't nice to maintain.
> 

Makes sense, which one of these would be preferred instead.

1. Call site is protected with HUGETLB_PAGE and CMA
2. Definition is protected with CMA and HUGETLB_PAGE - in arch/arm64/mm/hugetlb.c
3. Declaration is in arch/arm64/include/asm/hugetlb.h (without any #ifdef)

OR

1. Definition is protected with CMA and HUGETLB_PAGE - in arch/arm64/mm/hugetlb.c
2. Stub definition and declaration with #ifdefs (HUGETLB_PAGE and CMA) in arch/arm64/mm/init.c
3. Call site is without any #ifdef


  reply	other threads:[~2020-06-24 12:22 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-23  6:21 [PATCH] arm64/hugetlb: Reserve CMA areas for gigantic pages on 16K and 64K configs Anshuman Khandual
2020-06-23  9:24 ` kernel test robot
2020-06-23 12:48   ` Anshuman Khandual
2020-06-23 16:40     ` Robin Murphy
2020-06-24  0:17       ` Anshuman Khandual
2020-06-24  9:45         ` Robin Murphy
2020-06-24 12:22           ` Anshuman Khandual [this message]
2020-06-26 18:42 ` kernel test robot

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