linux-kernel - Re: [PATCH v2] mm/hugetlb: fix a addressing exception caused by huge_pte

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Date:   Tue, 24 Mar 2020 08:25:09 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Jason Gunthorpe <jgg@...pe.ca>,
        "Longpeng (Mike, Cloud Infrastructure Service Product Dept.)" 
        <longpeng2@...wei.com>
Cc:     akpm@...ux-foundation.org, kirill.shutemov@...ux.intel.com,
        linux-kernel@...r.kernel.org, arei.gonglei@...wei.com,
        weidong.huang@...wei.com, weifuqiang@...wei.com,
        kvm@...r.kernel.org, linux-mm@...ck.org,
        Matthew Wilcox <willy@...radead.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH v2] mm/hugetlb: fix a addressing exception caused by
 huge_pte_offset()

On 3/24/20 4:55 AM, Jason Gunthorpe wrote:
> Also, since CH moved all the get_user_pages_fast code out of the
> arch's many/all archs can drop their arch specific version of this
> routine. This is really just a specialized version of gup_fast's
> algorithm..
> 
> (also the arch versions seem different, why do some return actual
>  ptes, not null?)

Not sure I understand that last question.  The return value should be
a *pte or null.

/*
 * huge_pte_offset() - Walk the page table to resolve the hugepage
 * entry at address @addr
 *
 * Return: Pointer to page table or swap entry (PUD or PMD) for
 * address @addr, or NULL if a p*d_none() entry is encountered and the
 * size @sz doesn't match the hugepage size at this level of the page
 * table.
 */
-- 
Mike Kravetz