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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tWKDz-0000000ECeU-1x9y; Fri, 10 Jan 2025 18:59:15 +0000 Date: Fri, 10 Jan 2025 18:59:15 +0000 From: Matthew Wilcox To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Muchun Song Subject: Re: [PATCH v1 6/6] mm/hugetlb: use folio->lru int demote_free_hugetlb_folios() Message-ID: References: <20250110182149.746551-1-david@redhat.com> <20250110182149.746551-7-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250110182149.746551-7-david@redhat.com> X-Rspamd-Server: rspam05 X-Stat-Signature: 8dmz4bw6ci1i8buezofxmc7mnjdybnbr X-Rspamd-Queue-Id: 537A040003 X-Rspam-User: X-HE-Tag: 1736535558-586073 X-HE-Meta: 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 vRHkW5Yv HD7TS3sAUmSpm92pN+ORqrMnUVp1lf/Mw+ORHttm27qyY29SZ355AJKzp8XvHgNJnJ2jUNhbhxX01r1mMnap87YFaMvmAfDlQlK8hNIXSBSFagHXmGbnJ4RThCHs1YC/KFrcax41b/py5UkNufndT5FNvBbWySwfq8r7Huzo0dxIubruc7T/RnGulcoWzCPsUmHV00qtyeHiHVVC1eAL3LSzRZNkPSyKoNeG2ijisCCBF8WmV9nXlsGckSRvnCKIh0E4vpj1RbAxmX8Y+F1ceD2nIjTfCzVMsSY5GePYNbdnL6Bs= 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 Fri, Jan 10, 2025 at 07:21:49PM +0100, David Hildenbrand wrote: > We are demoting hugetlb folios to smaller hugetlb folios; let's avoid > messing with pages where avoidable. > > Signed-off-by: David Hildenbrand Good stuff. I have questions. > +++ b/mm/hugetlb.c > @@ -3822,13 +3822,15 @@ static long demote_free_hugetlb_folios(struct hstate *src, struct hstate *dst, > > for (i = 0; i < pages_per_huge_page(src); i += pages_per_huge_page(dst)) { > struct page *page = folio_page(folio, i); > + struct folio *new_folio; I'm usually very against casting from page to folio, but I think it might be the better option in this case ... > page->mapping = NULL; because then we could do new_folio->mapping = NULL. We're going to have to do serious changes to this function anyway to convert from Ottawa to the New York interpretation, so the cast doesn't give me the feeling of danger that it would elsewhere. > clear_compound_head(page); > prep_compound_page(page, dst->order); > + new_folio = page_folio(page); > > - init_new_hugetlb_folio(dst, page_folio(page)); > - list_add(&page->lru, &dst_list); > + init_new_hugetlb_folio(dst, new_folio); > + list_add(&new_folio->lru, &dst_list); > } > } > > -- > 2.47.1 >