From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757202Ab3CDLPm (ORCPT ); Mon, 4 Mar 2013 06:15:42 -0500 Received: from us01smtp3.synopsys.com ([198.182.44.81]:45604 "EHLO hermes.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756877Ab3CDLPl (ORCPT ); Mon, 4 Mar 2013 06:15:41 -0500 Message-ID: <5134824D.9070008@synopsys.com> Date: Mon, 4 Mar 2013 16:45:25 +0530 From: Vineet Gupta User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 MIME-Version: 1.0 Newsgroups: gmane.linux.kernel.mm,gmane.linux.kernel To: Andrew Morton CC: Tejun Heo , Yinghai Lu , Wanpeng Li , Ingo Molnar , , Subject: Re: [PATCH v3 1/2] memblock: add assertion for zero allocation alignment References: <1361479940-8078-1-git-send-email-vgupta@synopsys.com> In-Reply-To: X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.12.197.217] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andrew, On Friday 22 February 2013 02:23 AM, Tejun Heo wrote: > On Thu, Feb 21, 2013 at 12:52 PM, Vineet Gupta > wrote: >> This came to light when calling memblock allocator from arc port (for >> copying flattended DT). If a "0" alignment is passed, the allocator >> round_up() call incorrectly rounds up the size to 0. >> >> round_up(num, alignto) => ((num - 1) | (alignto -1)) + 1 >> >> While the obvious allocation failure causes kernel to panic, it is >> better to warn the caller to fix the code. >> >> Tejun suggested that instead of BUG_ON(!align) - which might be >> ineffective due to pending console init and such, it is better to >> WARN_ON, and continue the boot with a reasonable default align. >> >> Caller passing @size need not be handled similarly as the subsequent >> panic will indicate that anyhow. >> >> Signed-off-by: Vineet Gupta >> Cc: Andrew Morton >> Cc: Tejun Heo >> Cc: Yinghai Lu >> Cc: Wanpeng Li >> Cc: Ingo Molnar >> Cc: linux-mm@kvack.org >> Cc: linux-kernel@vger.kernel.org > > Acked-by: Tejun Heo > > Thanks. > I'm hoping this will be routed via the mm tree. Thx, -Vineet From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx182.postini.com [74.125.245.182]) by kanga.kvack.org (Postfix) with SMTP id AAF666B0002 for ; Mon, 4 Mar 2013 06:15:41 -0500 (EST) Message-ID: <5134824D.9070008@synopsys.com> Date: Mon, 4 Mar 2013 16:45:25 +0530 From: Vineet Gupta MIME-Version: 1.0 Subject: Re: [PATCH v3 1/2] memblock: add assertion for zero allocation alignment References: <1361479940-8078-1-git-send-email-vgupta@synopsys.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Tejun Heo , Yinghai Lu , Wanpeng Li , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org Hi Andrew, On Friday 22 February 2013 02:23 AM, Tejun Heo wrote: > On Thu, Feb 21, 2013 at 12:52 PM, Vineet Gupta > wrote: >> This came to light when calling memblock allocator from arc port (for >> copying flattended DT). If a "0" alignment is passed, the allocator >> round_up() call incorrectly rounds up the size to 0. >> >> round_up(num, alignto) => ((num - 1) | (alignto -1)) + 1 >> >> While the obvious allocation failure causes kernel to panic, it is >> better to warn the caller to fix the code. >> >> Tejun suggested that instead of BUG_ON(!align) - which might be >> ineffective due to pending console init and such, it is better to >> WARN_ON, and continue the boot with a reasonable default align. >> >> Caller passing @size need not be handled similarly as the subsequent >> panic will indicate that anyhow. >> >> Signed-off-by: Vineet Gupta >> Cc: Andrew Morton >> Cc: Tejun Heo >> Cc: Yinghai Lu >> Cc: Wanpeng Li >> Cc: Ingo Molnar >> Cc: linux-mm@kvack.org >> Cc: linux-kernel@vger.kernel.org > > Acked-by: Tejun Heo > > Thanks. > I'm hoping this will be routed via the mm tree. Thx, -Vineet -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org