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Date:   Wed, 16 Nov 2022 17:02:17 -0500
From:   Peter Xu <peterx@redhat.com>
To:     James Houghton <jthoughton@google.com>
Cc:     Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <songmuchun@bytedance.com>,
        David Hildenbrand <david@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Mina Almasry <almasrymina@google.com>,
        Zach O'Keefe <zokeefe@google.com>,
        Manish Mishra <manish.mishra@nutanix.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Baolin Wang <baolin.wang@linux.alibaba.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Yang Shi <shy828301@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 12/47] hugetlb: add hugetlb_hgm_walk and
 hugetlb_walk_step
Message-ID: <Y3Vd6dxNvGguCyxi@x1n>
References: <20221021163703.3218176-1-jthoughton@google.com>
 <20221021163703.3218176-13-jthoughton@google.com>
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On Fri, Oct 21, 2022 at 04:36:28PM +0000, James Houghton wrote:
> +/* hugetlb_hgm_walk - walks a high-granularity HugeTLB page table to resolve
> + * the page table entry for @addr.
> + *
> + * @hpte must always be pointing at an hstate-level PTE (or deeper).
> + *
> + * This function will never walk further if it encounters a PTE of a size
> + * less than or equal to @sz.
> + *
> + * @stop_at_none determines what we do when we encounter an empty PTE.

IIUC it is not about empty PTE but swap-or-empty pte?

I'm not sure whether it'll be more straightforward to have "bool alloc"
just to show whether the caller would like to allocate pgtables when
walking the sub-level pgtable until the level specified.

In final version of the code I also think we should drop all the "/*
stop_at_pte */" comments in the callers. Maybe that already means the
meaning of the bool is confusing so we always need a hint.

-- 
Peter Xu