Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751376AbdFZF2f (ORCPT ); Mon, 26 Jun 2017 01:28:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:60063 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750788AbdFZF2b (ORCPT ); Mon, 26 Jun 2017 01:28:31 -0400 Date: Mon, 26 Jun 2017 07:28:27 +0200 From: Michal Hocko To: Andrew Morton Cc: Vlastimil Babka , Johannes Weiner , Mel Gorman , NeilBrown , LKML , linux-mm@kvack.org Subject: Re: [PATCH 6/6] mm, migration: do not trigger OOM killer when migrating memory Message-ID: <20170626052827.GA31972@dhcp22.suse.cz> References: <20170623085345.11304-1-mhocko@kernel.org> <20170623085345.11304-7-mhocko@kernel.org> <20170623134305.4f59f673051120f95303fd89@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170623134305.4f59f673051120f95303fd89@linux-foundation.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1840 Lines: 55 On Fri 23-06-17 13:43:05, Andrew Morton wrote: > On Fri, 23 Jun 2017 10:53:45 +0200 Michal Hocko wrote: > > > From: Michal Hocko > > > > Page migration (for memory hotplug, soft_offline_page or mbind) needs > > to allocate a new memory. This can trigger an oom killer if the target > > memory is depleated. Although quite unlikely, still possible, especially > > for the memory hotplug (offlining of memoery). Up to now we didn't > > really have reasonable means to back off. __GFP_NORETRY can fail just > > too easily and __GFP_THISNODE sticks to a single node and that is not > > suitable for all callers. > > > > But now that we have __GFP_RETRY_MAYFAIL we should use it. It is > > preferable to fail the migration than disrupt the system by killing some > > processes. > > I'm not sure which tree this is against... next-20170623 > > > --- a/mm/memory-failure.c > > +++ b/mm/memory-failure.c > > @@ -1492,7 +1492,8 @@ static struct page *new_page(struct page *p, unsigned long private, int **x) > > > > return alloc_huge_page_node(hstate, nid); > > } else { > > - return __alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0); > > + return __alloc_pages_node(nid, > > + GFP_HIGHUSER_MOVABLE | __GFP_RETRY_MAYFAIL, 0); > > } > > } > > new_page() is now > > static struct page *new_page(struct page *p, unsigned long private, int **x) > { > int nid = page_to_nid(p); > > return new_page_nodemask(p, nid, &node_states[N_MEMORY]); > } > > and new_page_nodemask() uses __GFP_RETRY_MAYFAIL so I simply dropped > the above hunk. Ohh, right. This is http://lkml.kernel.org/r/20170622193034.28972-4-mhocko@kernel.org. I've just didn't realize it was not in mmotm yet. So yes the hunk can be dropped, new_page_nodemask does what we need. Sorry about that -- Michal Hocko SUSE Labs