From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754913Ab3L0WTy (ORCPT ); Fri, 27 Dec 2013 17:19:54 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:51217 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754815Ab3L0WTx (ORCPT ); Fri, 27 Dec 2013 17:19:53 -0500 Message-ID: <52BDFD00.7020909@oracle.com> Date: Fri, 27 Dec 2013 17:19:44 -0500 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: "Kirill A. Shutemov" CC: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE References: <1388114452-30769-1-git-send-email-sasha.levin@oracle.com> <20131227103847.GA19453@node.dhcp.inet.fi> In-Reply-To: <20131227103847.GA19453@node.dhcp.inet.fi> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/27/2013 05:38 AM, Kirill A. Shutemov wrote: > On Thu, Dec 26, 2013 at 10:20:52PM -0500, Sasha Levin wrote: >> Most of the VM_BUG_ON assertions are performed on a page. Usually, when >> one of these assertions fails we'll get a BUG_ON with a call stack and >> the registers. >> >> I've recently noticed based on the requests to add a small piece of code >> that dumps the page to various VM_BUG_ON sites that the page dump is quite >> useful to people debugging issues in mm. >> >> This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what >> VM_BUG_ON() does, also dumps the page before executing the actual BUG_ON. >> >> Signed-off-by: Sasha Levin > > I like the idea. One thing I've noticed you have a lot of page flag based > asserts, like: > > VM_BUG_ON_PAGE(PageLRU(page), page); > VM_BUG_ON_PAGE(!PageLocked(page), page); > > What about adding per-page-flag assert macros, like: > > PageNotLRU_assert(page); > PageLocked_assert(page); > > ? This way we will always dump right page on bug. > Sure, sounds good. I'll send another patch on top of this one. Thanks, Sasha