From patchwork Thu Oct 13 00:20:18 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Stoakes X-Patchwork-Id: 9374217 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 17BD1607FD for ; Thu, 13 Oct 2016 04:11:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 053AB2715B for ; Thu, 13 Oct 2016 04:11:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id ED2C628CEA; Thu, 13 Oct 2016 04:11:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.3 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM, T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 875842715B for ; Thu, 13 Oct 2016 04:11:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754763AbcJMEL5 (ORCPT ); Thu, 13 Oct 2016 00:11:57 -0400 Received: from mail-lf0-f68.google.com ([209.85.215.68]:33166 "EHLO mail-lf0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754822AbcJMELz (ORCPT ); Thu, 13 Oct 2016 00:11:55 -0400 Received: by mail-lf0-f68.google.com with SMTP id l131so7565854lfl.0; Wed, 12 Oct 2016 21:11:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=YtCTnPnKl7iOzKo94LN8YtKRwhKeaOyj++/afSUhTg8=; b=T8lGnI3g8EgzPX2ur/FmxLhX1Qvi3z2z14HovnNxNT9T+DGUy5gnRVABy/tTPZEVvl EPWDDhpc+byHt3iebnB2GFt7XZLRBjUOgtPQv3EYC8Bfs2sUxGz5zGpd3znmoG5VqTE6 TQBXyofuyuKOgD800XXdIUh0HCjQkWgvGxj7ioFI3i/L+sPN9RDdQhlUizfivrDQBmVJ q+rLPIbHiUlJ2RTIS6QfINu+iXFjzirMlJnbFyvTNtBTXUTvY8f2lor/ezyHKvgwVbSm MW9sFjSoZiKtiFp5HuoT0YL2qW/HlfMTH52tMfkF4apqGUcq7Ryf4RFvqiWkzH44RapR oX6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=YtCTnPnKl7iOzKo94LN8YtKRwhKeaOyj++/afSUhTg8=; b=d8MQFzkhRsUYI+x+/BphF10R3QAT1DOVLl8GyMIIJlaYbSM/zq1kKijKZ6Y8Sfqunc sxTWm3uxGfClI99RznklN+7UYMULeHG9tAC3UlUvrq6V+Fgj6+TZ36/xRC1/95tn5Gux GXnsiWQuAj9fPCcQlaNGfXD4+2I/f7mDRoDHAWhgeM8TQ0d+fe4hPW0mjo8Ig602M+Gp J9DFQEMB/AxzkcUnU+yoiG2v/sIU+3uyGExik1wPASRW9Qo4T0EaAnfpVxScmhKrGQBB A7yjTo0N4HNL+6qqoMyHzLorid4ISIFnW7mNVfmmg6xNfZQEgivXxuFYnzBcVB9Fc5Gj qSng== X-Gm-Message-State: AA6/9Rm0n6oDmnvm/UrftaP4niVeBqL4o2FsFDCdxcSSFuYvmGoA7ZxfewH/l5ubCMLeGQ== X-Received: by 10.28.175.77 with SMTP id y74mr17295wme.114.1476318042381; Wed, 12 Oct 2016 17:20:42 -0700 (PDT) Received: from localhost (cpc94060-newt37-2-0-cust185.19-3.cable.virginm.net. [92.234.204.186]) by smtp.gmail.com with ESMTPSA id v3sm17413357wjm.4.2016.10.12.17.20.40 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 12 Oct 2016 17:20:40 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org Cc: Linus Torvalds , Jan Kara , Hugh Dickins , Dave Hansen , Rik van Riel , Mel Gorman , Andrew Morton , adi-buildroot-devel@lists.sourceforge.net, ceph-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, kvm@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cris-kernel@axis.com, linux-fbdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-mips@linux-mips.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-scsi@vger.kernel.org, linux-security-module@vger.kernel.org, linux-sh@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, Lorenzo Stoakes Subject: [PATCH 08/10] mm: replace __access_remote_vm() write parameter with gup_flags Date: Thu, 13 Oct 2016 01:20:18 +0100 Message-Id: <20161013002020.3062-9-lstoakes@gmail.com> X-Mailer: git-send-email 2.10.0 In-Reply-To: <20161013002020.3062-1-lstoakes@gmail.com> References: <20161013002020.3062-1-lstoakes@gmail.com> Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch removes the write parameter from __access_remote_vm() and replaces it with a gup_flags parameter as use of this function previously _implied_ FOLL_FORCE, whereas after this patch callers explicitly pass this flag. We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by: Lorenzo Stoakes --- mm/memory.c | 23 +++++++++++++++-------- mm/nommu.c | 9 ++++++--- 2 files changed, 21 insertions(+), 11 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 20a9adb..79ebed3 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3869,14 +3869,11 @@ EXPORT_SYMBOL_GPL(generic_access_phys); * given task for page fault accounting. */ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, - unsigned long addr, void *buf, int len, int write) + unsigned long addr, void *buf, int len, unsigned int gup_flags) { struct vm_area_struct *vma; void *old_buf = buf; - unsigned int flags = FOLL_FORCE; - - if (write) - flags |= FOLL_WRITE; + int write = gup_flags & FOLL_WRITE; down_read(&mm->mmap_sem); /* ignore errors, just check how much was successfully transferred */ @@ -3886,7 +3883,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, struct page *page = NULL; ret = get_user_pages_remote(tsk, mm, addr, 1, - flags, &page, &vma); + gup_flags, &page, &vma); if (ret <= 0) { #ifndef CONFIG_HAVE_IOREMAP_PROT break; @@ -3945,7 +3942,12 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, int access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, int len, int write) { - return __access_remote_vm(NULL, mm, addr, buf, len, write); + unsigned int flags = FOLL_FORCE; + + if (write) + flags |= FOLL_WRITE; + + return __access_remote_vm(NULL, mm, addr, buf, len, flags); } /* @@ -3958,12 +3960,17 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, { struct mm_struct *mm; int ret; + unsigned int flags = FOLL_FORCE; mm = get_task_mm(tsk); if (!mm) return 0; - ret = __access_remote_vm(tsk, mm, addr, buf, len, write); + if (write) + flags |= FOLL_WRITE; + + ret = __access_remote_vm(tsk, mm, addr, buf, len, flags); + mmput(mm); return ret; diff --git a/mm/nommu.c b/mm/nommu.c index 70cb844..bde7df3 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1809,9 +1809,10 @@ void filemap_map_pages(struct fault_env *fe, EXPORT_SYMBOL(filemap_map_pages); static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, - unsigned long addr, void *buf, int len, int write) + unsigned long addr, void *buf, int len, unsigned int gup_flags) { struct vm_area_struct *vma; + int write = gup_flags & FOLL_WRITE; down_read(&mm->mmap_sem); @@ -1853,7 +1854,8 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, int access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, int len, int write) { - return __access_remote_vm(NULL, mm, addr, buf, len, write); + return __access_remote_vm(NULL, mm, addr, buf, len, + write ? FOLL_WRITE : 0); } /* @@ -1871,7 +1873,8 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in if (!mm) return 0; - len = __access_remote_vm(tsk, mm, addr, buf, len, write); + len = __access_remote_vm(tsk, mm, addr, buf, len, + write ? FOLL_WRITE : 0); mmput(mm); return len;