From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f52.google.com (mail-ee0-f52.google.com [74.125.83.52]) by kanga.kvack.org (Postfix) with ESMTP id A278A6B0031 for ; Fri, 27 Dec 2013 06:11:04 -0500 (EST) Received: by mail-ee0-f52.google.com with SMTP id d17so4054584eek.39 for ; Fri, 27 Dec 2013 03:11:04 -0800 (PST) Received: from jenni2.inet.fi (mta-out.inet.fi. [195.156.147.13]) by mx.google.com with ESMTP id s8si37676702eeh.143.2013.12.27.03.11.02 for ; Fri, 27 Dec 2013 03:11:02 -0800 (PST) Date: Fri, 27 Dec 2013 12:38:47 +0200 From: "Kirill A. Shutemov" Subject: Re: [PATCH] mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE Message-ID: <20131227103847.GA19453@node.dhcp.inet.fi> References: <1388114452-30769-1-git-send-email-sasha.levin@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1388114452-30769-1-git-send-email-sasha.levin@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Sasha Levin Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org 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. -- Kirill A. Shutemov -- 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