From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id D41AA6B002C for ; Wed, 19 Oct 2011 15:42:28 -0400 (EDT) Received: from wpaz29.hot.corp.google.com (wpaz29.hot.corp.google.com [172.24.198.93]) by smtp-out.google.com with ESMTP id p9JJgLv7011882 for ; Wed, 19 Oct 2011 12:42:21 -0700 Received: from iaen33 (iaen33.prod.google.com [10.12.165.33]) by wpaz29.hot.corp.google.com with ESMTP id p9JJfqHV004767 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Wed, 19 Oct 2011 12:42:20 -0700 Received: by iaen33 with SMTP id n33so4629503iae.3 for ; Wed, 19 Oct 2011 12:42:19 -0700 (PDT) Date: Wed, 19 Oct 2011 12:42:15 -0700 (PDT) From: Hugh Dickins 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> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: 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 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 -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org