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Subject: Re: [PATCH v2 03/40] mm/rmap: introduce and use
 hugetlb_add_file_rmap()
From: Muchun Song <muchun.song@linux.dev>
In-Reply-To: <20231220224504.646757-4-david@redhat.com>
Date: Thu, 21 Dec 2023 10:58:07 +0800
Cc: LKML <linux-kernel@vger.kernel.org>,
 Linux-MM <linux-mm@kvack.org>,
 Andrew Morton <akpm@linux-foundation.org>,
 "Matthew Wilcox (Oracle)" <willy@infradead.org>,
 Hugh Dickins <hughd@google.com>,
 Ryan Roberts <ryan.roberts@arm.com>,
 Yin Fengwei <fengwei.yin@intel.com>,
 Mike Kravetz <mike.kravetz@oracle.com>,
 Peter Xu <peterx@redhat.com>
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Message-Id: <F867DDC7-CB8A-4E41-8773-8EE5404F1DF9@linux.dev>
References: <20231220224504.646757-1-david@redhat.com>
 <20231220224504.646757-4-david@redhat.com>
To: David Hildenbrand <david@redhat.com>


> On Dec 21, 2023, at 06:44, David Hildenbrand <david@redhat.com> wrote:
> 
> hugetlb rmap handling differs quite a lot from "ordinary" rmap code.
> For example, hugetlb currently only supports entire mappings, and treats
> any mapping as mapped using a single "logical PTE". Let's move it out
> of the way so we can overhaul our "ordinary" rmap.
> implementation/interface.
> 
> Right now we're using page_dup_file_rmap() in some cases where "ordinary"
> rmap code would have used page_add_file_rmap(). So let's introduce and
> use hugetlb_add_file_rmap() instead. We won't be adding a
> "hugetlb_dup_file_rmap()" functon for the fork() case, as it would be
> doing the same: "dup" is just an optimization for "add".
> 
> What remains is a single page_dup_file_rmap() call in fork() code.
> 
> Add sanity checks that we end up with the right folios in the right
> functions.
> 
> Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
> Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Muchun Song <songmuchun@bytedance.com>

Thanks.