linux-kernel - Re: [PATCH v3 0/4] Clean up hugetlb boot command line processing

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Date:   Tue, 21 Apr 2020 00:53:26 +0200
From:   Anders Roxell <anders.roxell@...aro.org>
To:     Mike Kravetz <mike.kravetz@...cle.com>
Cc:     Will Deacon <will@...nel.org>, Qian Cai <cai@....pw>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        sparclinux@...r.kernel.org, linux-doc@...r.kernel.org,
        Catalin Marinas <catalin.marinas@....com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        "David S.Miller" <davem@...emloft.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Jonathan Corbet <corbet@....net>,
        Longpeng <longpeng2@...wei.com>,
        Christophe Leroy <christophe.leroy@....fr>,
        Randy Dunlap <rdunlap@...radead.org>,
        Mina Almasry <almasrymina@...gle.com>,
        Peter Xu <peterx@...hat.com>,
        Nitesh Narayan Lal <nitesh@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v3 0/4] Clean up hugetlb boot command line processing

On Mon, 20 Apr 2020 at 23:43, Mike Kravetz <mike.kravetz@...cle.com> wrote:
>
> On 4/20/20 1:29 PM, Anders Roxell wrote:
> > On Mon, 20 Apr 2020 at 20:23, Mike Kravetz <mike.kravetz@...cle.com> wrote:
> >> On 4/20/20 8:34 AM, Qian Cai wrote:
> >>>
> >>> Reverted this series fixed many undefined behaviors on arm64 with the config,
> >> While rearranging the code (patch 3 in series), I made the incorrect
> >> assumption that CONT_XXX_SIZE == (1UL << CONT_XXX_SHIFT).  However,
> >> this is not the case.  Does the following patch fix these issues?
> >>
> >> From b75cb4a0852e208bee8c4eb347dc076fcaa88859 Mon Sep 17 00:00:00 2001
> >> From: Mike Kravetz <mike.kravetz@...cle.com>
> >> Date: Mon, 20 Apr 2020 10:41:18 -0700
> >> Subject: [PATCH] arm64/hugetlb: fix hugetlb initialization
> >>
> >> When calling hugetlb_add_hstate() to initialize a new hugetlb size,
> >> be sure to use correct huge pages size order.
> >>
> >> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
> >> ---
> >>  arch/arm64/mm/hugetlbpage.c | 8 ++++----
> >>  1 file changed, 4 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> >> index 9ca840527296..a02411a1f19a 100644
> >> --- a/arch/arm64/mm/hugetlbpage.c
> >> +++ b/arch/arm64/mm/hugetlbpage.c
> >> @@ -453,11 +453,11 @@ void huge_ptep_clear_flush(struct vm_area_struct *vma,
> >>  static int __init hugetlbpage_init(void)
> >>  {
> >>  #ifdef CONFIG_ARM64_4K_PAGES
> >> -       hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
> >> +       hugetlb_add_hstate(ilog2(PUD_SIZE) - PAGE_SHIFT);
> >>  #endif
> >> -       hugetlb_add_hstate(CONT_PMD_SHIFT - PAGE_SHIFT);
> >> -       hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
> >> -       hugetlb_add_hstate(CONT_PTE_SHIFT - PAGE_SHIFT);
> >> +       hugetlb_add_hstate(ilog2(CONT_PMD_SIZE) - PAGE_SHIFT);
> >> +       hugetlb_add_hstate(ilog2(PMD_SIZE) - PAGE_SHIFT);
> >> +       hugetlb_add_hstate(ilog2(CONT_PTE_SIZE) - PAGE_SHIFT);
> >>
> >>         return 0;
> >>  }
> >
> > I build this for an arm64 kernel and ran it in qemu and it worked.
>
> Thanks for testing Anders!
>
> Will, here is an updated version of the patch based on your suggestion.
> I added the () for emphasis but that may just be noise for some.  Also,
> the naming differences and values for CONT_PTE may make some people
> look twice.  Not sure if being consistent here helps?
>
> I have only built this.  No testing.
>
> From daf833ab6b806ecc0816d84d45dcbacc052a7eec Mon Sep 17 00:00:00 2001
> From: Mike Kravetz <mike.kravetz@...cle.com>
> Date: Mon, 20 Apr 2020 13:56:15 -0700
> Subject: [PATCH] arm64/hugetlb: fix hugetlb initialization
>
> When calling hugetlb_add_hstate() to initialize a new hugetlb size,
> be sure to use correct huge pages size order.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>

Tested-by: Anders Roxell <anders.roxell@...aro.org>

I tested this patch on qemu-aarch64.

Cheers,
Anders

> ---
>  arch/arm64/mm/hugetlbpage.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 9ca840527296..bed6dc7c4276 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -455,9 +455,9 @@ static int __init hugetlbpage_init(void)
>  #ifdef CONFIG_ARM64_4K_PAGES
>         hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
>  #endif
> -       hugetlb_add_hstate(CONT_PMD_SHIFT - PAGE_SHIFT);
> +       hugetlb_add_hstate((CONT_PMD_SHIFT + PMD_SHIFT) - PAGE_SHIFT);
>         hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
> -       hugetlb_add_hstate(CONT_PTE_SHIFT - PAGE_SHIFT);
> +       hugetlb_add_hstate((CONT_PTE_SHIFT + PAGE_SHIFT) - PAGE_SHIFT);
>
>         return 0;
>  }
> --
> 2.25.2
>