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=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 3A920C4360C for ; Thu, 10 Oct 2019 13:41:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 148D12067B for ; Thu, 10 Oct 2019 13:41:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=shipmail.org header.i=@shipmail.org header.b="XJ9AzqJr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388108AbfJJNlV (ORCPT ); Thu, 10 Oct 2019 09:41:21 -0400 Received: from pio-pvt-msa2.bahnhof.se ([79.136.2.41]:51172 "EHLO pio-pvt-msa2.bahnhof.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727800AbfJJNlU (ORCPT ); Thu, 10 Oct 2019 09:41:20 -0400 Received: from localhost (localhost [127.0.0.1]) by pio-pvt-msa2.bahnhof.se (Postfix) with ESMTP id A5BEB3F32B; Thu, 10 Oct 2019 15:41:18 +0200 (CEST) Authentication-Results: pio-pvt-msa2.bahnhof.se; dkim=pass (1024-bit key; unprotected) header.d=shipmail.org header.i=@shipmail.org header.b=XJ9AzqJr; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at bahnhof.se Received: from pio-pvt-msa2.bahnhof.se ([127.0.0.1]) by localhost (pio-pvt-msa2.bahnhof.se [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id PvCIW3Nwcj92; Thu, 10 Oct 2019 15:41:17 +0200 (CEST) Received: from mail1.shipmail.org (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) (Authenticated sender: mb878879) by pio-pvt-msa2.bahnhof.se (Postfix) with ESMTPA id 9D2A63F260; Thu, 10 Oct 2019 15:41:17 +0200 (CEST) Received: from localhost.localdomain.localdomain (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) by mail1.shipmail.org (Postfix) with ESMTPSA id 658F43610CE; Thu, 10 Oct 2019 15:41:17 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=shipmail.org; s=mail; t=1570714877; bh=I43d2BTecvoJPXAN1AxjOTn1uEK1Ks5L6V9rF+kVywU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XJ9AzqJrkAVMR4RNVKFniF4BTgPqdLa+jiit+c4NumrcPH91KNui0QgSnvzaT0h1b Enxl+sJfziYIHP/L28Sv0vj8uxgmRM2AahsWxj9JoVctrzhjNVkJE+FO9HLi2E7dhY lXbUSY8Vh8b7YI3Shl123a996WCXuLCV5pRMl4V0= From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m=20=28VMware=29?= To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, torvalds@linux-foundation.org, kirill@shutemov.name Cc: Thomas Hellstrom Subject: [RFC PATCH 3/4] mm: pagewalk: Disallow user positive callback return values and use them for walk control Date: Thu, 10 Oct 2019 15:40:57 +0200 Message-Id: <20191010134058.11949-4-thomas_os@shipmail.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20191010134058.11949-1-thomas_os@shipmail.org> References: <20191010134058.11949-1-thomas_os@shipmail.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Linus Torvalds When we have both a pmd_entry() and a pte_entry() callback, in some siutaions it is desirable not to traverse the pte level. Reserve positive callback return values for walk control and define a return value PAGE_WALK_CONTINUE that means skip lower level traversal and continue the walk. Co-developed-by: Thomas Hellstrom Signed-off-by: Thomas Hellstrom --- include/linux/pagewalk.h | 6 ++++++ mm/pagewalk.c | 9 ++++++--- 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h index 6ec82e92c87f..d9e5d1927315 100644 --- a/include/linux/pagewalk.h +++ b/include/linux/pagewalk.h @@ -4,6 +4,12 @@ #include +/* + * pmd_entry() Return code meaning skip to next entry. + * Don't look for lower levels + */ +#define PAGE_WALK_CONTINUE 1 + struct mm_walk; /** diff --git a/mm/pagewalk.c b/mm/pagewalk.c index ea0b9e606ad1..d2483d432fda 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -52,8 +52,12 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, */ if (ops->pmd_entry) err = ops->pmd_entry(pmd, addr, next, walk); - if (err) + if (err < 0) break; + if (err == PAGE_WALK_CONTINUE) { + err = 0; + continue; + } /* * Check this here so we only break down trans_huge @@ -291,8 +295,7 @@ static int __walk_page_range(unsigned long start, unsigned long end, * * - 0 : succeeded to handle the current entry, and if you don't reach the * end address yet, continue to walk. - * - >0 : succeeded to handle the current entry, and return to the caller - * with caller specific value. + * - >0 : Reserved for walk control. Use only PAGE_WALK_XX values. * - <0 : failed to handle the current entry, and return to the caller * with error code. * -- 2.21.0