Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752705AbbKPBf6 (ORCPT ); Sun, 15 Nov 2015 20:35:58 -0500 Received: from mail-pa0-f50.google.com ([209.85.220.50]:36499 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752054AbbKPBf5 convert rfc822-to-8bit (ORCPT ); Sun, 15 Nov 2015 20:35:57 -0500 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.0 \(3094\)) Subject: Re: [PATCH V4] mm: fix kernel crash in khugepaged thread From: yalin wang In-Reply-To: <20151113090115.1ad4235b@gandalf.local.home> Date: Mon, 16 Nov 2015 09:35:53 +0800 Cc: Vlastimil Babka , Ingo Molnar , Andrew Morton , Ebru Akagunduz , Rik van Riel , "Kirill A. Shutemov" , jmarchan@redhat.com, mgorman@techsingularity.net, willy@linux.intel.com, linux-kernel , linux-mm@kvack.org Content-Transfer-Encoding: 8BIT Message-Id: <2F74FF6B-66DC-4BF9-972A-C2F5FFFA979F@gmail.com> References: <1447316462-19645-1-git-send-email-yalin.wang2010@gmail.com> <20151112092923.19ee53dd@gandalf.local.home> <5645BFAA.1070004@suse.cz> <20151113090115.1ad4235b@gandalf.local.home> To: Steven Rostedt X-Mailer: Apple Mail (2.3094) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1415 Lines: 40 > On Nov 13, 2015, at 22:01, Steven Rostedt wrote: > > On Fri, 13 Nov 2015 19:54:11 +0800 > yalin wang wrote: > >>>>> TP_fast_assign( >>>>> __entry->mm = mm; >>>>> - __entry->pfn = pfn; >>>>> + __entry->pfn = page_to_pfn(page); >>>> >>>> Instead of the condition, we could have: >>>> >>>> __entry->pfn = page ? page_to_pfn(page) : -1; >>> >>> I agree. Please do it like this. > > hmm, pfn is defined as an unsigned long, would -1 be the best. > Or should it be (-1UL). > > Then we could also have: > > TP_printk("mm=%p, scan_pfn=0x%lx%s, writable=%d, referenced=%d, none_or_zero=%d, status=%s, unmapped=%d", > __entry->mm, > __entry->pfn == (-1UL) ? 0 : __entry->pfn, > __entry->pfn == (-1UL) ? "(null)" : "", > > Note the added %s after %lx I have in the print format. > > -- Steve it is not easy to print for perf tools in userspace , if you use this format , for user space perf tool, it print the entry by look up the member in entry struct by offset , you print a dynamic string which user space perf tool don’t know how to print this string . Thanks -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/