From patchwork Tue Jan 26 15:59:20 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 60468 Delivered-To: patch@linaro.org Received: by 10.112.130.2 with SMTP id oa2csp2045681lbb; Tue, 26 Jan 2016 07:59:30 -0800 (PST) X-Received: by 10.98.70.90 with SMTP id t87mr35075805pfa.110.1453823970450; Tue, 26 Jan 2016 07:59:30 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id st8si2783240pab.53.2016.01.26.07.59.30; Tue, 26 Jan 2016 07:59:30 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966575AbcAZP72 (ORCPT + 30 others); Tue, 26 Jan 2016 10:59:28 -0500 Received: from foss.arm.com ([217.140.101.70]:46325 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751019AbcAZP7Z (ORCPT ); Tue, 26 Jan 2016 10:59:25 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6515B49; Tue, 26 Jan 2016 07:58:44 -0800 (PST) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7AA2A3F2E5; Tue, 26 Jan 2016 07:59:24 -0800 (PST) Date: Tue, 26 Jan 2016 15:59:20 +0000 From: Will Deacon To: mika.penttila@nextfour.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux@arm.linux.org.uk, catalin.marinas@arm.com Subject: Re: [PATCH v2 RESEND 1/2] arm, arm64: change_memory_common with numpages == 0 should be no-op. Message-ID: <20160126155919.GA28238@arm.com> References: <1453820393-31179-1-git-send-email-mika.penttila@nextfour.com> <1453820393-31179-2-git-send-email-mika.penttila@nextfour.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1453820393-31179-2-git-send-email-mika.penttila@nextfour.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mika, On Tue, Jan 26, 2016 at 04:59:52PM +0200, mika.penttila@nextfour.com wrote: > From: Mika Penttilä > > This makes the caller set_memory_xx() consistent with x86. > > arm64 part is rebased on 4.5.0-rc1 with Ard's patch > lkml.kernel.org/g/<1453125665-26627-1-git-send-email-ard.biesheuvel@linaro.org> > applied. > > Signed-off-by: Mika Penttilä mika.penttila@nextfour.com > Reviewed-by: Laura Abbott > Acked-by: David Rientjes > > --- > arch/arm/mm/pageattr.c | 3 +++ > arch/arm64/mm/pageattr.c | 3 +++ > 2 files changed, 6 insertions(+) > > diff --git a/arch/arm/mm/pageattr.c b/arch/arm/mm/pageattr.c > index cf30daf..d19b1ad 100644 > --- a/arch/arm/mm/pageattr.c > +++ b/arch/arm/mm/pageattr.c > @@ -49,6 +49,9 @@ static int change_memory_common(unsigned long addr, int numpages, > WARN_ON_ONCE(1); > } > > + if (!numpages) > + return 0; > + > if (start < MODULES_VADDR || start >= MODULES_END) > return -EINVAL; > > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > index 1360a02..b582fc2 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -53,6 +53,9 @@ static int change_memory_common(unsigned long addr, int numpages, > WARN_ON_ONCE(1); > } > > + if (!numpages) > + return 0; > + Thanks for this. I can reproduce the failure on my Juno board, so I'd like to queue this for 4.5 since it fixes a real issue. I've taken the liberty of rebasing the arm64 part to my fixes branch and writing a commit message. Does the patch below look ok to you? Will --->8 >From 57adec866c0440976c96a4b8f5b59fb411b1cacb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Mika=20Penttil=C3=A4?= Date: Tue, 26 Jan 2016 15:47:25 +0000 Subject: [PATCH] arm64: mm: avoid calling apply_to_page_range on empty range MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Calling apply_to_page_range with an empty range results in a BUG_ON from the core code. This can be triggered by trying to load the st_drv module with CONFIG_DEBUG_SET_MODULE_RONX enabled: kernel BUG at mm/memory.c:1874! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in: CPU: 3 PID: 1764 Comm: insmod Not tainted 4.5.0-rc1+ #2 Hardware name: ARM Juno development board (r0) (DT) task: ffffffc9763b8000 ti: ffffffc975af8000 task.ti: ffffffc975af8000 PC is at apply_to_page_range+0x2cc/0x2d0 LR is at change_memory_common+0x80/0x108 This patch fixes the issue by making change_memory_common (called by the set_memory_* functions) a NOP when numpages == 0, therefore avoiding the erroneous call to apply_to_page_range and bringing us into line with x86 and s390. Cc: Reviewed-by: Laura Abbott Acked-by: David Rientjes Signed-off-by: Mika Penttilä Signed-off-by: Will Deacon --- arch/arm64/mm/pageattr.c | 3 +++ 1 file changed, 3 insertions(+) -- 2.1.4 diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 3571c7309c5e..cf6240741134 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -57,6 +57,9 @@ static int change_memory_common(unsigned long addr, int numpages, if (end < MODULES_VADDR || end >= MODULES_END) return -EINVAL; + if (!numpages) + return 0; + data.set_mask = set_mask; data.clear_mask = clear_mask;