From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753219Ab1JSTm0 (ORCPT ); Wed, 19 Oct 2011 15:42:26 -0400 Received: from smtp-out.google.com ([74.125.121.67]:3241 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753049Ab1JSTmZ (ORCPT ); Wed, 19 Oct 2011 15:42:25 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=dkim-signature:date:from:x-x-sender:to:cc:subject: in-reply-to:message-id:references:user-agent:mime-version:content-type:x-system-of-record; b=rb7qOt64UhAm0jFw8ciHoPL5aaQ79Bo53IflwhE3IjYDrlCmzwCpJFE7gP9tdI4Jk /oUVBf/rmuGexqJrDCaPQ== Date: Wed, 19 Oct 2011 12:42:15 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@sister.anvils To: Linus Torvalds cc: Mel Gorman , Andrea Arcangeli , Pawel Sikora , Andrew Morton , linux-mm@kvack.org, jpiszcz@lucidpixels.com, arekm@pld-linux.org, linux-kernel@vger.kernel.org Subject: Re: kernel 3.0: BUG: soft lockup: find_get_pages+0x51/0x110 In-Reply-To: Message-ID: References: <201110122012.33767.pluto@agmk.net> <20111016235442.GB25266@redhat.com> <20111019074336.GB3410@suse.de> User-Agent: Alpine 2.00 (LSU 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Oct 2011, Linus Torvalds wrote: > On Wed, Oct 19, 2011 at 12:43 AM, Mel Gorman wrote: > > > > My vote is with the migration change. While there are occasionally > > patches to make migration go faster, I don't consider it a hot path. > > mremap may be used intensively by JVMs so I'd loathe to hurt it. > > Ok, everybody seems to like that more, and it removes code rather than > adds it, so I certainly prefer it too. Pawel, can you test that other > patch (to mm/migrate.c) that Hugh posted? Instead of the mremap vma > locking patch that you already verified for your setup? > > Hugh - that one didn't have a changelog/sign-off, so if you could > write that up, and Pawel's testing is successful, I can apply it... > Looks like we have acks from both Andrea and Mel. Yes, I'm glad to have that input from Andrea and Mel, thank you. Here we go. I can't add a Tested-by since Pawel was reporting on the alternative patch, but perhaps you'll be able to add that in later. I may have read too much into Pawel's mail, but it sounded like he would have expected an eponymous find_get_pages() lockup by now, and was pleased that this patch appeared to have cured that. I've spent quite a while trying to explain find_get_pages() lockup by a missed migration entry, but I just don't see it: I don't expect this (or the alternative) patch to do anything to fix that problem. I won't mind if it magically goes away, but I expect we'll need more info from the debug patch I sent Justin a couple of days ago. Ah, I'd better send the patch separately as "[PATCH] mm: fix race between mremap and removing migration entry": Pawel's "l" makes my old alpine setup choose quoted printable when I reply to your mail. Hugh