From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx195.postini.com [74.125.245.195]) by kanga.kvack.org (Postfix) with SMTP id 1351A6B0068 for ; Thu, 9 Aug 2012 21:27:23 -0400 (EDT) Received: by ggnf4 with SMTP id f4so1348442ggn.14 for ; Thu, 09 Aug 2012 18:27:22 -0700 (PDT) Date: Thu, 9 Aug 2012 18:26:34 -0700 (PDT) From: Hugh Dickins Subject: Re: [patch] mmap: feed back correct prev vma when finding vma In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Hillf Danton Cc: KOSAKI Motohiro , Mikulas Patocka , Andrew Morton , LKML , Linux-MM On Thu, 9 Aug 2012, Hillf Danton wrote: > After walking rb tree, if vma is determined, prev vma has to be determined > based on vma; and rb_prev should be considered only if no vma determined. Why? Because you think more code is better code? I disagree. If you have seen a bug here, please tell how to reproduce it. I have not heard of a bug here: I think you're saying, if the rbtree were inconsistent with the vma list, then you think it would be a good idea to believe the vma list instead of the rbtree where there's a choice. But the rbtree had better not be inconsistent with the vma list. Hugh > > Signed-off-by: Hillf Danton > --- > > --- a/mm/mmap.c Fri Aug 3 07:38:10 2012 > +++ b/mm/mmap.c Mon Aug 6 20:10:18 2012 > @@ -385,9 +385,13 @@ find_vma_prepare(struct mm_struct *mm, u > } > } > > - *pprev = NULL; > - if (rb_prev) > - *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); > + if (vma) { > + *pprev = vma->vm_prev; > + } else { > + *pprev = NULL; > + if (rb_prev) > + *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); > + } > *rb_link = __rb_link; > *rb_parent = __rb_parent; > return vma; > -- -- 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