From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94270C07D5A for ; Mon, 27 Nov 2023 10:35:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232981AbjK0KfA (ORCPT ); Mon, 27 Nov 2023 05:35:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37220 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232972AbjK0Ke5 (ORCPT ); Mon, 27 Nov 2023 05:34:57 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id F0482E1 for ; Mon, 27 Nov 2023 02:35:03 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 35E8F2F4; Mon, 27 Nov 2023 02:35:51 -0800 (PST) Received: from [10.57.73.191] (unknown [10.57.73.191]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BF31F3F73F; Mon, 27 Nov 2023 02:35:00 -0800 (PST) Message-ID: <48417f46-d01c-48d1-b53e-d9458a1527fe@arm.com> Date: Mon, 27 Nov 2023 10:34:59 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND PATCH v7 02/10] mm: Non-pmd-mappable, large folios for folio_add_new_anon_rmap() Content-Language: en-GB To: David Hildenbrand , Andrew Morton , Matthew Wilcox , Yin Fengwei , Yu Zhao , Catalin Marinas , Anshuman Khandual , Yang Shi , "Huang, Ying" , Zi Yan , Luis Chamberlain , Itaru Kitayama , "Kirill A. Shutemov" , John Hubbard , David Rientjes , Vlastimil Babka , Hugh Dickins , Kefeng Wang Cc: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20231122162950.3854897-1-ryan.roberts@arm.com> <20231122162950.3854897-3-ryan.roberts@arm.com> From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/11/2023 17:40, David Hildenbrand wrote: > On 22.11.23 17:29, Ryan Roberts wrote: >> In preparation for supporting anonymous small-sized THP, improve >> folio_add_new_anon_rmap() to allow a non-pmd-mappable, large folio to be >> passed to it. In this case, all contained pages are accounted using the >> order-0 folio (or base page) scheme. >> >> Reviewed-by: Yu Zhao >> Reviewed-by: Yin Fengwei >> Signed-off-by: Ryan Roberts >> --- >>   mm/rmap.c | 28 ++++++++++++++++++++-------- >>   1 file changed, 20 insertions(+), 8 deletions(-) >> >> diff --git a/mm/rmap.c b/mm/rmap.c >> index 49e4d86a4f70..b086dc957b0c 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1305,32 +1305,44 @@ void page_add_anon_rmap(struct page *page, struct >> vm_area_struct *vma, >>    * This means the inc-and-test can be bypassed. >>    * The folio does not have to be locked. >>    * >> - * If the folio is large, it is accounted as a THP.  As the folio >> + * If the folio is pmd-mappable, it is accounted as a THP.  As the folio >>    * is new, it's assumed to be mapped exclusively by a single process. >>    */ >>   void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, >>           unsigned long address) >>   { >> -    int nr; >> +    int nr = folio_nr_pages(folio); >> >> -    VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); >> +    VM_BUG_ON_VMA(address < vma->vm_start || >> +            address + (nr << PAGE_SHIFT) > vma->vm_end, vma); >>       __folio_set_swapbacked(folio); >> +    __folio_set_anon(folio, vma, address, true); > > Likely the changed order doesn't matter. Yes; the reason I moved __folio_set_anon() up here is because SetPageAnonExclusive() asserts that the page is anon, and SetPageAnonExclusive() has to be called differently for the 3 cases. I couldn't see any reason why it wouldn't be safe to call __folio_set_anon() before setting up the mapcounts. > > LGTM > > Reviewed-by: David Hildenbrand > Thanks!