Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933401AbbKMKZX (ORCPT ); Fri, 13 Nov 2015 05:25:23 -0500 Received: from mail-pa0-f42.google.com ([209.85.220.42]:35576 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932418AbbKMKYc convert rfc822-to-8bit (ORCPT ); Fri, 13 Nov 2015 05:24:32 -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: <0ab001d11def$081c80d0$18558270$@alibaba-inc.com> Date: Fri, 13 Nov 2015 18:24:24 +0800 Cc: Steven Rostedt , Ingo Molnar , Andrew Morton , Rik van Riel , "Kirill A. Shutemov" , Vlastimil Babka , Mel Gorman , linux-kernel , linux-mm@kvack.org Content-Transfer-Encoding: 8BIT Message-Id: <031A099B-6020-4946-896F-92D3CBE9443B@gmail.com> References: <0ab001d11def$081c80d0$18558270$@alibaba-inc.com> To: Hillf Danton 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: 1197 Lines: 39 > On Nov 13, 2015, at 16:41, Hillf Danton wrote: > >> >> Instead of the condition, we could have: >> >> __entry->pfn = page ? page_to_pfn(page) : -1; >> >> >> But if there's no reason to do the tracepoint if page is NULL, then >> this patch is fine. I'm just throwing out this idea. >> > we trace only if page is valid > > --- linux-next/mm/huge_memory.c Fri Nov 13 16:00:22 2015 > +++ b/mm/huge_memory.c Fri Nov 13 16:26:19 2015 > @@ -1987,7 +1987,8 @@ static int __collapse_huge_page_isolate( > > out: > release_pte_pages(pte, _pte); > - trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero, > + if (page) > + trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero, > referenced, writable, result); > return 0; > } > — > my V4 patch move if (!page) into trace function, so that we don’t need call page_to_fn() if the trace if disabled . more efficient . 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/