linux-kernel - Re: [PATCH v3] mm/hugetlb: fix a addressing exception caused by huge_pte

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Message-ID: <20200327121100.GR20941@ziepe.ca>
Date:   Fri, 27 Mar 2020 09:11:00 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     "Longpeng(Mike)" <longpeng2@...wei.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kvm@...r.kernel.org, arei.gonglei@...wei.com,
        weidong.huang@...wei.com, weifuqiang@...wei.com,
        kirill.shutemov@...ux.intel.com,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH v3] mm/hugetlb: fix a addressing exception caused by
 huge_pte_offset

On Fri, Mar 27, 2020 at 09:40:07AM +0800, Longpeng(Mike) wrote:
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index dd8737a..d4fab68 100644
> +++ b/mm/hugetlb.c
> @@ -4909,29 +4909,33 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
>  		       unsigned long addr, unsigned long sz)
>  {
>  	pgd_t *pgd;
> -	p4d_t *p4d;
> -	pud_t *pud;
> -	pmd_t *pmd;
> +	p4d_t *p4g, p4d_entry;
> +	pud_t *pud, pud_entry;
> +	pmd_t *pmd, pmd_entry;
>  
>  	pgd = pgd_offset(mm, addr);
>  	if (!pgd_present(*pgd))
>  		return NULL;
> -	p4d = p4d_offset(pgd, addr);
> -	if (!p4d_present(*p4d))
> +
> +	p4g = p4d_offset(pgd, addr);

Why p4g here? Shouldn't it be p4d?

Jason