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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pIkBk-001hds-Qp; Fri, 20 Jan 2023 05:43:44 +0000 Date: Fri, 20 Jan 2023 05:43:44 +0000 From: Matthew Wilcox To: Sidhartha Kumar Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, songmuchun@bytedance.com, mike.kravetz@oracle.com, jhubbard@nvidia.com Subject: Re: [PATCH 2/9] mm/hugetlb: convert hugetlbfs_pagecache_present() to folios Message-ID: References: <20230119211446.54165-1-sidhartha.kumar@oracle.com> <20230119211446.54165-3-sidhartha.kumar@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230119211446.54165-3-sidhartha.kumar@oracle.com> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: EC16F100002 X-Stat-Signature: iu3x354rcqqobgbq1q8naqkbdhfafh6z X-HE-Tag: 1674193435-889598 X-HE-Meta: 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 s9V0J+Tw rBeHDnewFUI+mQC3qt+E4XqeLP5ucuQvVoI8DDxc+mpms53x+pZ0NT7hXy52ZD9E0eJVth/sN92M2ay+2Bd0j5rsCK4D1vPxCJ0ypzQGyCbqJRnNn+oTugvbBmGv0jAv0Bl9T8CxksDnq3tqHZH5708oTxt8P7kXcFi1cPwSt3hRBrJtfRqwfbNjH9k1Pnaa+kWNZ8osC82dKm/E= 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: On Thu, Jan 19, 2023 at 01:14:39PM -0800, Sidhartha Kumar wrote: > +++ b/mm/hugetlb.c > @@ -5653,15 +5653,15 @@ static bool hugetlbfs_pagecache_present(struct hstate *h, > { > struct address_space *mapping; > pgoff_t idx; > - struct page *page; > + struct folio *folio; > > mapping = vma->vm_file->f_mapping; > idx = vma_hugecache_offset(h, vma, address); > > - page = find_get_page(mapping, idx); > - if (page) > - put_page(page); > - return page != NULL; > + folio = filemap_get_folio(mapping, idx); > + if (folio) > + folio_put(folio); > + return folio != NULL; > } Seems to me this function could be ... struct address_space *mapping = vma->vm_file->f_mapping; pgoff_t index = vma_hugecache_offset(h, vma, address); bool present; rcu_read_lock(); present = page_cache_next_miss(mapping, index, 1) != index; rcu_read_unlock(); return present; No need to get/drop a refcount on the folio. It's a bit similar to filemap_range_has_page(), but the API is wrong. Maybe there's room for a little refactoring here.