From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx134.postini.com [74.125.245.134]) by kanga.kvack.org (Postfix) with SMTP id 25A496B0044 for ; Wed, 11 Apr 2012 16:53:43 -0400 (EDT) Message-ID: <4F85EEED.1090906@parallels.com> Date: Wed, 11 Apr 2012 17:51:57 -0300 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH] remove BUG() in possible but rare condition References: <1334167824-19142-1-git-send-email-glommer@parallels.com> <20120411132635.bfddc6bd.akpm@linux-foundation.org> In-Reply-To: <20120411132635.bfddc6bd.akpm@linux-foundation.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, devel@openvz.org, linux-mm@kvack.org, cgroups@vger.kernel.org, Michal Hocko , Johannes Weiner , kamezawa.hiroyu@jp.fujitsu.com, Greg Thelen , Suleiman Souhlal , Linus Torvalds On 04/11/2012 05:26 PM, Andrew Morton wrote: >> >> > failed: >> > - BUG(); >> > unlock_page(page); >> > page_cache_release(page); >> > return NULL; > Cute. > > AFAICT what happened was that in my April 2002 rewrite of this code I > put a non-fatal buffer_error() warning in that case to tell us that > something bad happened. > > Years later we removed the temporary buffer_error() and mistakenly > replaced that warning with a BUG(). Only it*can* happen. > > We can remove the BUG() and fix up callers, or we can pass retry=1 into > alloc_page_buffers(), so grow_dev_page() "cannot fail". Immortal > functions are a silly fiction, so we should remove the BUG() and fix up > callers. > Any particular caller you are concerned with ? As I mentioned, this function already returns NULL for other reason - that seem even more probable than this specific failure. So whoever is not checking this return value, is already broken without this patch as well. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org