From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id 0556228024D for ; Wed, 21 Sep 2016 18:35:37 -0400 (EDT) Received: by mail-qt0-f197.google.com with SMTP id l91so133355347qte.3 for ; Wed, 21 Sep 2016 15:35:37 -0700 (PDT) Received: from sender153-mail.zoho.com (sender153-mail.zoho.com. [74.201.84.153]) by mx.google.com with ESMTPS id b47si25218124qte.116.2016.09.21.15.35.36 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 21 Sep 2016 15:35:36 -0700 (PDT) Subject: Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area() References: <57E20B54.5020408@zoho.com> From: zijun_hu Message-ID: <034db3ec-e2dc-a6da-6dab-f0803900e19d@zoho.com> Date: Thu, 22 Sep 2016 06:35:19 +0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: zijun_hu@htc.com, Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, tj@kernel.org, mingo@kernel.org, iamjoonsoo.kim@lge.com, mgorman@techsingularity.net On 2016/9/22 5:10, David Rientjes wrote: > On Wed, 21 Sep 2016, zijun_hu wrote: > >> From: zijun_hu >> >> correct a few logic error for __insert_vmap_area() since the else >> if condition is always true and meaningless >> >> in order to fix this issue, if vmap_area inserted is lower than one >> on rbtree then walk around left branch; if higher then right branch >> otherwise intersects with the other then BUG_ON() is triggered >> > > Under normal operation, you're right that the "else if" conditional should > always succeed: we don't want to BUG() unless there's a bug. The original > code can catch instances when va->va_start == tmp_va->va_end where we > should BUG(). Your code silently ignores it. > Hmm, the BUG_ON() appears in the original code, i don't introduce it. it maybe be better to consider va->va_start == tmp_va->va_end as normal case and should not BUG_ON() it since the available range of vmap_erea include the start boundary but the end, BTW, represented as [start, end) this patch correct the logic to that mentioned in the comments, it maybe be more logical and more understandable -- 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