From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx161.postini.com [74.125.245.161]) by kanga.kvack.org (Postfix) with SMTP id 91E4D6B0002 for ; Thu, 21 Feb 2013 15:31:35 -0500 (EST) Received: by mail-ie0-f180.google.com with SMTP id bn7so12040771ieb.11 for ; Thu, 21 Feb 2013 12:31:34 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1361477421-3964-1-git-send-email-vgupta@synopsys.com> References: <20130221193639.GN3570@htj.dyndns.org> <1361477421-3964-1-git-send-email-vgupta@synopsys.com> Date: Thu, 21 Feb 2013 12:31:34 -0800 Message-ID: Subject: Re: [PATCH v2 1/2] memblock: add assertion for zero allocation alignment From: Yinghai Lu Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Vineet Gupta Cc: Tejun Heo , Andrew Morton , Wanpeng Li , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Feb 21, 2013 at 12:10 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 > --- > mm/memblock.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 1bcd9b9..f3804bd 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -824,6 +824,9 @@ 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); > > + if (WARN_ON(!align)) > + align = __alignof__(long long); > + the checking should be put before round_up? > 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, 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