From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f44.google.com (mail-wm0-f44.google.com [74.125.82.44]) by kanga.kvack.org (Postfix) with ESMTP id A9FE46B0253 for ; Thu, 7 Apr 2016 11:22:37 -0400 (EDT) Received: by mail-wm0-f44.google.com with SMTP id v188so60335414wme.1 for ; Thu, 07 Apr 2016 08:22:37 -0700 (PDT) Received: from mail-wm0-f50.google.com (mail-wm0-f50.google.com. [74.125.82.50]) by mx.google.com with ESMTPS id g72si9482870wmi.124.2016.04.07.08.22.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Apr 2016 08:22:36 -0700 (PDT) Received: by mail-wm0-f50.google.com with SMTP id 191so95533148wmq.0 for ; Thu, 07 Apr 2016 08:22:36 -0700 (PDT) Date: Thu, 7 Apr 2016 17:22:35 +0200 From: Michal Hocko Subject: Re: Re: Re: PG_reserved and compound pages Message-ID: <20160407152234.GE32755@dhcp22.suse.cz> References: <4482994.u2S3pScRyb@noys2> <3877205.TjDYue2aah@noys2> <20160406153343.GJ24272@dhcp22.suse.cz> <20567553.kUaGmfXpqH@noys2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20567553.kUaGmfXpqH@noys2> Sender: owner-linux-mm@kvack.org List-ID: To: Frank Mehnert Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org On Thu 07-04-16 15:45:02, Frank Mehnert wrote: > On Wednesday 06 April 2016 17:33:43 Michal Hocko wrote: [...] > > 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. > > Yes, such memory objects are also mapped to userland. Do you think that > VM_IO or VM_PFNMAP would guard against NUMA page migration? Both auto numa and manual numa migration checks vma_migratable and that excludes both VM flags. > Because when > NUMA page migration was introduced (I believe with Linux 3.8) I tested > both flags and saw that they didn't prevent the migration on such VM > areas. Maybe this changed in the meantime, do you have more information > about that? I haven't checked the history much but vma_migratable should be there for quite some time. Maybe it wasn't used in the past. Dunno > The drawback of at least VM_IO is that such memory is not part of a core > dump. that seems to be correct as per vma_dump_size > Actually currently we use vm_insert_page() for userland mapping > and mark the VM areas as > > VM_DONTEXPAND | VM_DONTDUMP but that means that it won't end up in the dump either. Or am I missing your point. -- 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