From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754175Ab3BUUxk (ORCPT ); Thu, 21 Feb 2013 15:53:40 -0500 Received: from mail-qa0-f53.google.com ([209.85.216.53]:60780 "EHLO mail-qa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753246Ab3BUUxj (ORCPT ); Thu, 21 Feb 2013 15:53:39 -0500 MIME-Version: 1.0 In-Reply-To: <1361479940-8078-1-git-send-email-vgupta@synopsys.com> References: <1361479940-8078-1-git-send-email-vgupta@synopsys.com> Date: Thu, 21 Feb 2013 12:53:38 -0800 X-Google-Sender-Auth: GzcTChrVeRvC6NUY0EpQQAqdc1s Message-ID: Subject: Re: [PATCH v3 1/2] memblock: add assertion for zero allocation alignment From: Tejun Heo To: Vineet Gupta Cc: Yinghai Lu , Andrew Morton , Wanpeng Li , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx204.postini.com [74.125.245.204]) by kanga.kvack.org (Postfix) with SMTP id 5C1256B0006 for ; Thu, 21 Feb 2013 15:53:39 -0500 (EST) Received: by mail-qa0-f47.google.com with SMTP id j8so68614qah.13 for ; Thu, 21 Feb 2013 12:53:38 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1361479940-8078-1-git-send-email-vgupta@synopsys.com> References: <1361479940-8078-1-git-send-email-vgupta@synopsys.com> Date: Thu, 21 Feb 2013 12:53:38 -0800 Message-ID: Subject: Re: [PATCH v3 1/2] memblock: add assertion for zero allocation alignment From: Tejun Heo Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Vineet Gupta Cc: Yinghai Lu , Andrew Morton , Wanpeng Li , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org 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. -- tejun -- 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