From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 31A908E0001 for ; Fri, 28 Dec 2018 05:49:09 -0500 (EST) Received: by mail-pf1-f199.google.com with SMTP id q63so23084082pfi.19 for ; Fri, 28 Dec 2018 02:49:09 -0800 (PST) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id u27si38587979pfa.103.2018.12.28.02.49.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 28 Dec 2018 02:49:07 -0800 (PST) Date: Fri, 28 Dec 2018 11:49:05 +0100 From: Greg Kroah-Hartman Subject: Re: stable request: mm, page_alloc: actually ignore mempolicies for high priority allocations Message-ID: <20181228104905.GA15967@kroah.com> References: <08ae2e51-672a-37de-2aa6-4e49dbc9de02@suse.cz> <20181108090154.GJ2453@dhcp22.suse.cz> <4ad07955-05d5-80ea-ebf1-876b0dc6347a@suse.cz> <7300a8a8-588a-2182-f11f-280cbce36fca@vyatta.att-mail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7300a8a8-588a-2182-f11f-280cbce36fca@vyatta.att-mail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Mike Manning Cc: Vlastimil Babka , Michal Hocko , stable@vger.kernel.org, Mel Gorman , linux-mm On Thu, Nov 08, 2018 at 09:41:37AM +0000, Mike Manning wrote: > On 08/11/2018 09:06, Vlastimil Babka wrote: > > On 11/8/18 10:01 AM, Michal Hocko wrote: > >> On Thu 08-11-18 08:30:40, Mike Manning wrote: > >> [...] > >>> 1) The original commit was not suitable for backport to 4.14 and should > >>> be reverted. > >> Yes, the original patch hasn't been marked for the stable tree and as > >> such shouldn't have been backported. Even though it looks simple enough > >> it is not really trivial. > > I think you confused the two patches. > > > > Original commit 1d26c112959f ("mm, page_alloc: do not break > > __GFP_THISNODE by zonelist reset") was marked for stable, especially > > pre-4.7 where SLAB could be potentially broken. > > > > Commit d6a24df00638 ("mm, page_alloc: actually ignore mempolicies for > > high priority allocations") was not marked stable and is being requested > > in this thread. But I'm reluctant to agree with this without properly > > understanding what went wrong. > > Apologies, the original commit was not a backport, but is a fix in 4.14 > for pre-4.7 kernels. > > All I can do from a user perspective is report the problem and the > fortuitous follow-on commit that resolved the issue in our case. It has > already taken quite some time to find that the problem was unexpectedly > due to the kernel upgrade (this failure is a first, we have been running > these tests for some years going back to the 4.1 kernel), then to go > through the process of pinpointing the change that caused the issue in > our case. > > Given that the problem is not manually reproducible, and given that it > could take a very substantial period of time to understand how the > change is impacting our scale & performance testing, it seems most > expedient to backport the 1-line commit that resolves the issue. Ok, you are asking for this to be added, without really knowing _why_ it resolves the issue and Michal is asking to know _why_ before acking it, correct? So I'll hold off on merging this for now until you all come to some kind of resolution :) thanks, greg k-h