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From: Mike Kravetz <mike.kravetz@oracle.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Barry Song <song.bao.hua@hisilicon.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH] arm64/hugetlb: fix CMA gigantic page order for non-4K PAGE_SIZE
Date: Tue, 5 Oct 2021 14:28:03 -0700	[thread overview]
Message-ID: <3747d914-c687-b983-c624-e3418b4d2448@oracle.com> (raw)
In-Reply-To: <20211005135435.341477bb4b50b84202c32450@linux-foundation.org>

On 10/5/21 1:54 PM, Andrew Morton wrote:
> On Tue,  5 Oct 2021 13:25:29 -0700 Mike Kravetz <mike.kravetz@oracle.com> wrote:
> 
>> For non-4K PAGE_SIZE configs, the largest gigantic huge page size is
>> CONT_PMD_SHIFT order.
> 
> What are the user visible effects of this bug?
> 
> 

Sorry,
I only recently got easy access to arm64 platforms.  This is what I saw
as a user:

The largest gigantic huge page size on arm64 with 64K PAGE_SIZE 64K is
16G.  Therefore, one should be able to specify 'hugetlb_cma=16G' on the
kernel command line so that 1 gigantic page can be allocated from CMA.
However, when adding such an option the following message is produced:

hugetlb_cma: cma area should be at least 8796093022208 MiB

This is because the calculation for non-4K gigantic page order is
incorrect in the arm64 specific routine arm64_hugetlb_cma_reserve().

Would you like me to send a new version with this in the commit message?
Or, is it easier for you to just add it?
-- 
Mike Kravetz

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-10-05 21:30 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-05 20:25 [PATCH] arm64/hugetlb: fix CMA gigantic page order for non-4K PAGE_SIZE Mike Kravetz
2021-10-05 20:54 ` Andrew Morton
2021-10-05 21:28   ` Mike Kravetz [this message]
2021-10-05 23:15     ` Andrew Morton
2021-10-06  7:55 ` Anshuman Khandual
2021-10-06 13:06 ` Catalin Marinas

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