From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH] mm/pgtable: Drop pgtable_t variable from pte_fn_t functions Date: Fri, 3 May 2019 06:27:33 -0700 Message-ID: <20190503132733.GA5201@bombadil.infradead.org> References: <1556803126-26596-1-git-send-email-anshuman.khandual@arm.com> <20190502134623.GA18948@bombadil.infradead.org> <20190502161457.1c9dbd94@mschwideX1> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190502161457.1c9dbd94@mschwideX1> Sender: linux-kernel-owner@vger.kernel.org To: Martin Schwidefsky Cc: Anshuman Khandual , akpm@linux-foundation.org, linux-mm@kvack.org, Ard Biesheuvel , Russell King , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Michal Hocko , Logan Gunthorpe , "Kirill A. Shutemov" , Dan Williams , jglisse@redhat.com, Mike Rapoport , x86@kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org List-Id: linux-efi@vger.kernel.org On Thu, May 02, 2019 at 04:14:57PM +0200, Martin Schwidefsky wrote: > On Thu, 2 May 2019 06:46:23 -0700 > Matthew Wilcox wrote: > > > On Thu, May 02, 2019 at 06:48:46PM +0530, Anshuman Khandual wrote: > > > Drop the pgtable_t variable from all implementation for pte_fn_t as none of > > > them use it. apply_to_pte_range() should stop computing it as well. Should > > > help us save some cycles. > > > > You didn't add Martin Schwidefsky for some reason. He introduced > > it originally for s390 for sub-page page tables back in 2008 (commit > > 2f569afd9c). I think he should confirm that he no longer needs it. > > With its 2K pte tables s390 can not deal with a (struct page *) as a reference > to a page table. But if there are no user of the apply_to_page_range() API > left which actually make use of the token argument we can safely drop it. Interestingly, I don't think there ever was a user which used that argument. Looking at your 2f56 patch, you only converted one function (presumably there was only one caller of apply_to_page_range() at the time), and it didn't u se any of the arguments. Xen was the initial user, and the two other functions they added also didn't use that argument. Looking at a quick sample of users added since, none of them appear to have ever used that argument. So removing it seems best. Acked-by: Matthew Wilcox 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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03C08C43219 for ; Fri, 3 May 2019 13:27:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7E752075E for ; Fri, 3 May 2019 13:27:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="T9s51+W+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727240AbfECN1p (ORCPT ); Fri, 3 May 2019 09:27:45 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:53688 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727231AbfECN1p (ORCPT ); Fri, 3 May 2019 09:27:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=mkGg1i+EI0XU//yFAO+gJW+bQDnnQU83x/RNkUevVAw=; b=T9s51+W+nABH6PVAvlfgP+ohw RCDyHolxbxOczp+Cg0V5Q3SXBf36YHMOis1fkWWpWSE0zZx6A65FVoDithh+5zNBA/L+/pInK3O58 PPdp9B6gb5Mj1aHlTOwgYd7feLRBi467iD6vPhfKK/abUZfZCHY1041K3TtWkrj1V0TUQ8aWIVhLI +/1YzsyjItpsKuqA6JsKXlZeS7WEi7325sCVTFrE7teQKa5lOodL28eu5Nt6D+miXBGjogCaXg8yc VVRuwIZrSBtfheGOujAaXemlnM9xeF/eEeaLHQrjpzSd4fVzD5UcaEhjqq1fDcHkpcop11b8UYehV hXvd6JaeQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hMYDu-0006ZD-4h; Fri, 03 May 2019 13:27:34 +0000 Date: Fri, 3 May 2019 06:27:33 -0700 From: Matthew Wilcox To: Martin Schwidefsky Cc: Anshuman Khandual , akpm@linux-foundation.org, linux-mm@kvack.org, Ard Biesheuvel , Russell King , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Michal Hocko , Logan Gunthorpe , "Kirill A. Shutemov" , Dan Williams , jglisse@redhat.com, Mike Rapoport , x86@kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH] mm/pgtable: Drop pgtable_t variable from pte_fn_t functions Message-ID: <20190503132733.GA5201@bombadil.infradead.org> References: <1556803126-26596-1-git-send-email-anshuman.khandual@arm.com> <20190502134623.GA18948@bombadil.infradead.org> <20190502161457.1c9dbd94@mschwideX1> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <20190502161457.1c9dbd94@mschwideX1> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Message-ID: <20190503132733.UQMbUCnjkTUU1eKIvUiPe2vgW_Zn-ltwdH3Mu-ggtEQ@z> On Thu, May 02, 2019 at 04:14:57PM +0200, Martin Schwidefsky wrote: > On Thu, 2 May 2019 06:46:23 -0700 > Matthew Wilcox wrote: > > > On Thu, May 02, 2019 at 06:48:46PM +0530, Anshuman Khandual wrote: > > > Drop the pgtable_t variable from all implementation for pte_fn_t as none of > > > them use it. apply_to_pte_range() should stop computing it as well. Should > > > help us save some cycles. > > > > You didn't add Martin Schwidefsky for some reason. He introduced > > it originally for s390 for sub-page page tables back in 2008 (commit > > 2f569afd9c). I think he should confirm that he no longer needs it. > > With its 2K pte tables s390 can not deal with a (struct page *) as a reference > to a page table. But if there are no user of the apply_to_page_range() API > left which actually make use of the token argument we can safely drop it. Interestingly, I don't think there ever was a user which used that argument. Looking at your 2f56 patch, you only converted one function (presumably there was only one caller of apply_to_page_range() at the time), and it didn't u se any of the arguments. Xen was the initial user, and the two other functions they added also didn't use that argument. Looking at a quick sample of users added since, none of them appear to have ever used that argument. So removing it seems best. Acked-by: Matthew Wilcox