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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rCjDv-0090sx-OC; Mon, 11 Dec 2023 16:33:39 +0000 Date: Mon, 11 Dec 2023 16:33:39 +0000 From: Matthew Wilcox To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Hugh Dickins , Ryan Roberts , Yin Fengwei , Mike Kravetz , Muchun Song , Peter Xu Subject: Re: [PATCH v1 02/39] mm/rmap: introduce and use hugetlb_remove_rmap() Message-ID: References: <20231211155652.131054-1-david@redhat.com> <20231211155652.131054-3-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231211155652.131054-3-david@redhat.com> X-Rspamd-Queue-Id: 2A41D1A001B X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: d4fdw8h6sixrkyfjk4xtdo4unzyjmza1 X-HE-Tag: 1702312424-290625 X-HE-Meta: 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 2MNCdqfK hXR3uVi8id95W32um8IAuRHXf53z8lyjPmqvtjQwNNifPseQKW9rcgkYB3SCe5QZB0MloNlSBTyYtrBErL699HZoUqcquK8HWEB3zjoAtwxh7OTBJMewtO2ifGcARvQxwPBeMFJEN4VqQo1PIPanFkW0ir1fEL5ZRbgjLJVgdTaBpWOfEE2LZnn/oljTtHarPrFkrWcRiy9m3E3kqlfeW7TD+b63gaouKprhLdxPW5lv4Io5DBodvuNFgFyuV0Bwzm2RpC3+9vWCLfR770lC5fDftHvvL98N3GEgR X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Dec 11, 2023 at 04:56:15PM +0100, David Hildenbrand 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. > > Let's introduce and use hugetlb_remove_rmap() and remove the hugetlb > code from page_remove_rmap(). This effectively removes one check on the > small-folio path as well. > > Note: all possible candidates that need care are page_remove_rmap() that > pass compound=true. > > Reviewed-by: Yin Fengwei > Signed-off-by: David Hildenbrand Reviewed-by: Matthew Wilcox (Oracle) > +++ b/mm/rmap.c > @@ -1482,13 +1482,6 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, > > VM_BUG_ON_PAGE(compound && !PageHead(page), page); > > - /* Hugetlb pages are not counted in NR_*MAPPED */ > - if (unlikely(folio_test_hugetlb(folio))) { > - /* hugetlb pages are always mapped with pmds */ > - atomic_dec(&folio->_entire_mapcount); > - return; > - } Maybe add VM_BUG_ON_FOLIO(folio_test_hugetlb(folio), folio);