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Date:   Fri, 12 May 2023 14:03:53 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Junxiao Chang <junxiao.chang@intel.com>
Cc:     kirill.shutemov@linux.intel.com, mhocko@suse.com,
        jmarchan@redhat.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, mike.kravetz@oracle.com,
        muchun.song@linux.dev
Subject: Re: [PATCH] mm: fix hugetlb page unmap count balance issue
Message-Id: <20230512140353.8b95e8cb024c8e7a1a3b03c1@linux-foundation.org>
In-Reply-To: <20230512072036.1027784-1-junxiao.chang@intel.com>
References: <20230512072036.1027784-1-junxiao.chang@intel.com>
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On Fri, 12 May 2023 15:20:36 +0800 Junxiao Chang <junxiao.chang@intel.com> wrote:

> hugetlb page usually is mapped with pmd, but occasionally it might be
> mapped with pte. QEMU can use udma-buf to create host dmabufs for guest
> framebuffers. When QEMU is launched with parameter "hugetlb=on",
> udmabuffer driver maps hugetlb page with pte in page fault handler.

Are there any other situations in which a hugetlb page is mapped in
this fashion?

If not, can QEMU be changed to map with a pmd?

So we get one less weird special case in MM.