From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f51.google.com (mail-wm0-f51.google.com [74.125.82.51]) by kanga.kvack.org (Postfix) with ESMTP id B8CBD6B0005 for ; Wed, 6 Apr 2016 11:33:46 -0400 (EDT) Received: by mail-wm0-f51.google.com with SMTP id f198so79047154wme.0 for ; Wed, 06 Apr 2016 08:33:46 -0700 (PDT) Received: from mail-wm0-f49.google.com (mail-wm0-f49.google.com. [74.125.82.49]) by mx.google.com with ESMTPS id ck9si3783126wjc.88.2016.04.06.08.33.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 Apr 2016 08:33:45 -0700 (PDT) Received: by mail-wm0-f49.google.com with SMTP id u206so51110844wme.1 for ; Wed, 06 Apr 2016 08:33:45 -0700 (PDT) Date: Wed, 6 Apr 2016 17:33:43 +0200 From: Michal Hocko Subject: Re: Re: PG_reserved and compound pages Message-ID: <20160406153343.GJ24272@dhcp22.suse.cz> References: <4482994.u2S3pScRyb@noys2> <20160406150206.GB24283@dhcp22.suse.cz> <3877205.TjDYue2aah@noys2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3877205.TjDYue2aah@noys2> Sender: owner-linux-mm@kvack.org List-ID: To: Frank Mehnert Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org On Wed 06-04-16 17:12:43, Frank Mehnert wrote: > Hi Michal, > > On Wednesday 06 April 2016 17:02:06 Michal Hocko wrote: > > [CCing linux-mm mailing list] > > > > On Wed 06-04-16 13:28:37, Frank Mehnert wrote: > > > Hi, > > > > > > Linux 4.5 introduced additional checks to ensure that compound pages are > > > never marked as reserved. In our code we use PG_reserved to ensure that > > > the kernel does never swap out such pages, e.g. > > > > Are you putting your pages on the LRU list? If not how they could get > > swapped out? > > No, we do nothing like that. It was my understanding that at least with > older kernels it was possible that pages allocated with alloc_pages() > could be swapped out or otherwise manipulated, I might be wrong. I do not see anything like that. All the evictable pages should be on a LRU. > For > instance, it's also necessary that the physical address of the page > is known and that it does never change. I know, there might be problems > with automatic NUMA page migration but that's another story. Do you map your pages to the userspace? If yes then vma with VM_IO or VM_PFNMAP should keep any attempt away from those pages. -- Michal Hocko SUSE Labs -- 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/ . Don't email: email@kvack.org