From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f71.google.com (mail-pa0-f71.google.com [209.85.220.71]) by kanga.kvack.org (Postfix) with ESMTP id 5F00A6B0038 for ; Fri, 7 Oct 2016 14:16:34 -0400 (EDT) Received: by mail-pa0-f71.google.com with SMTP id tz10so33608888pab.3 for ; Fri, 07 Oct 2016 11:16:34 -0700 (PDT) Received: from mail-pf0-x236.google.com (mail-pf0-x236.google.com. [2607:f8b0:400e:c00::236]) by mx.google.com with ESMTPS id yn6si17977037pab.271.2016.10.07.11.16.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Oct 2016 11:16:33 -0700 (PDT) Received: by mail-pf0-x236.google.com with SMTP id i85so26833683pfa.3 for ; Fri, 07 Oct 2016 11:16:33 -0700 (PDT) Date: Fri, 7 Oct 2016 11:16:26 -0700 (PDT) From: Hugh Dickins Subject: Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing In-Reply-To: <20161007162240.GA14350@lucifer> Message-ID: References: <20160911225425.10388-1-lstoakes@gmail.com> <20160925184731.GA20480@lucifer> <1474842875.17726.38.camel@redhat.com> <20161007100720.GA14859@lucifer> <20161007162240.GA14350@lucifer> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Lorenzo Stoakes Cc: Linus Torvalds , Jan Kara , Dave Hansen , Rik van Riel , Hugh Dickins , linux-mm , Mel Gorman , tbsaunde@tbsaunde.org, robert@ocallahan.org, Linux Kernel Mailing List , Andrew Morton On Fri, 7 Oct 2016, Lorenzo Stoakes wrote: > On Fri, Oct 07, 2016 at 08:34:15AM -0700, Linus Torvalds wrote: > > Would you be willing to look at doing that kind of purely syntactic, > > non-semantic cleanup first? > > Sure, more than happy to do that! I'll work on a patch for this. > > > I think that if we end up having the FOLL_FORCE semantics, we're > > actually better off having an explicit FOLL_FORCE flag, and *not* do > > some kind of implicit "under these magical circumstances we'll force > > it anyway". The implicit thing is what we used to do long long ago, we > > definitely don't want to. > > That's a good point, it would definitely be considerably more 'magical', and > expanding the conditions to include uprobes etc. would only add to that. > > I wondered about an alternative parameter/flag but it felt like it was > more-or-less FOLL_FORCE in a different form, at which point it may as well > remain FOLL_FORCE :) Adding Jan Kara (and Dave Hansen) to the Cc list: I think they were pursuing get_user_pages() cleanups last year (which would remove the force option from most callers anyway), and I've lost track of where that all got to. Lorenzo, please don't expend a lot of effort before checking with Jan. 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/ . Don't email: email@kvack.org