From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752586Ab3BUT1S (ORCPT ); Thu, 21 Feb 2013 14:27:18 -0500 Received: from mail-ia0-f176.google.com ([209.85.210.176]:43957 "EHLO mail-ia0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751740Ab3BUT1Q (ORCPT ); Thu, 21 Feb 2013 14:27:16 -0500 MIME-Version: 1.0 In-Reply-To: <1361471962-25164-2-git-send-email-vgupta@synopsys.com> References: <1361471962-25164-1-git-send-email-vgupta@synopsys.com> <1361471962-25164-2-git-send-email-vgupta@synopsys.com> Date: Thu, 21 Feb 2013 11:27:16 -0800 X-Google-Sender-Auth: oMwIgOK_1Y5CUv-rKBKwCJ7A23E Message-ID: Subject: Re: [PATCH 1/2] memblock: add assertion for zero allocation size From: Yinghai Lu To: Vineet Gupta , "H. Peter Anvin" Cc: Andrew Morton , Chris Zankel , Max Filippov , Marc Gauthier , Tejun Heo , 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 [+Cc: hpa] On Thu, Feb 21, 2013 at 10:39 AM, 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 BUG_ON() if effective size for allocation (as passed by caller > and/or computed after alignemtn rounding) is zero. should we just make align to 1 instead of 0 ? or BUG_ON(!align) instead? > > 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 > --- > mm/memblock.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 1bcd9b9..32b36d0 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -824,6 +824,8 @@ static phys_addr_t __init memblock_alloc_base_nid(phys_addr_t size, > /* align @size to avoid excessive fragmentation on reserved array */ > size = round_up(size, align); > > + BUG_ON(!size); > + > found = memblock_find_in_range_node(0, max_addr, size, align, nid); > if (found && !memblock_reserve(found, size)) > return found; > -- > 1.7.4.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx120.postini.com [74.125.245.120]) by kanga.kvack.org (Postfix) with SMTP id 07F146B0002 for ; Thu, 21 Feb 2013 14:27:16 -0500 (EST) Received: by mail-ie0-f171.google.com with SMTP id 10so11838236ied.30 for ; Thu, 21 Feb 2013 11:27:16 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1361471962-25164-2-git-send-email-vgupta@synopsys.com> References: <1361471962-25164-1-git-send-email-vgupta@synopsys.com> <1361471962-25164-2-git-send-email-vgupta@synopsys.com> Date: Thu, 21 Feb 2013 11:27:16 -0800 Message-ID: Subject: Re: [PATCH 1/2] memblock: add assertion for zero allocation size From: Yinghai Lu Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Vineet Gupta , "H. Peter Anvin" Cc: Andrew Morton , Chris Zankel , Max Filippov , Marc Gauthier , Tejun Heo , Wanpeng Li , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org [+Cc: hpa] On Thu, Feb 21, 2013 at 10:39 AM, 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 BUG_ON() if effective size for allocation (as passed by caller > and/or computed after alignemtn rounding) is zero. should we just make align to 1 instead of 0 ? or BUG_ON(!align) instead? > > 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 > --- > mm/memblock.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 1bcd9b9..32b36d0 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -824,6 +824,8 @@ static phys_addr_t __init memblock_alloc_base_nid(phys_addr_t size, > /* align @size to avoid excessive fragmentation on reserved array */ > size = round_up(size, align); > > + BUG_ON(!size); > + > found = memblock_find_in_range_node(0, max_addr, size, align, nid); > if (found && !memblock_reserve(found, size)) > return found; > -- > 1.7.4.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- 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