From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f43.google.com (mail-pa0-f43.google.com [209.85.220.43]) by kanga.kvack.org (Postfix) with ESMTP id 70F1E6B0254 for ; Thu, 22 Oct 2015 11:15:18 -0400 (EDT) Received: by pacfv9 with SMTP id fv9so93388289pac.3 for ; Thu, 22 Oct 2015 08:15:18 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2001:1868:205::9]) by mx.google.com with ESMTPS id a16si21738657pbu.151.2015.10.22.08.15.17 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 22 Oct 2015 08:15:17 -0700 (PDT) Date: Thu, 22 Oct 2015 17:15:09 +0200 From: Peter Zijlstra Subject: Re: [PATCH 14/23] userfaultfd: wake pending userfaults Message-ID: <20151022151509.GO3604@twins.programming.kicks-ass.net> References: <1431624680-20153-1-git-send-email-aarcange@redhat.com> <1431624680-20153-15-git-send-email-aarcange@redhat.com> <20151022121056.GB7520@twins.programming.kicks-ass.net> <20151022132015.GF19147@redhat.com> <20151022133824.GR17308@twins.programming.kicks-ass.net> <20151022141831.GA1331@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151022141831.GA1331@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org, kvm@vger.kernel.org, linux-api@vger.kernel.org, Pavel Emelyanov , Sanidhya Kashyap , zhang.zhanghailiang@huawei.com, Linus Torvalds , "Kirill A. Shutemov" , Andres Lagar-Cavilla , Dave Hansen , Paolo Bonzini , Rik van Riel , Mel Gorman , Andy Lutomirski , Hugh Dickins , Peter Feiner , "Dr. David Alan Gilbert" , Johannes Weiner , "Huangpeng (Peter)" On Thu, Oct 22, 2015 at 04:18:31PM +0200, Andrea Arcangeli wrote: > The risk of memory corruption is still zero no matter what happens > here, in the extremely rare case the app will get a SIGBUS or a That might still upset people, SIGBUS isn't something an app can really recover from. > I'm not exactly sure why we allow VM_FAULT_RETRY only once currently > so I'm tempted to drop FAULT_FLAG_TRIED entirely. I think to ensure we make forward progress. > I've no real preference on how to tweak the page fault code to be able > to return VM_FAULT_RETRY indefinitely and I would aim for the smallest > change possible, so if you've suggestions now it's good time. Indefinitely is such a long time, we should try and finish computation before the computer dies etc. :-) Yes, yes.. I know, extremely unlikely etc. Still guarantees are good. In any case, I'm not really too bothered how you fix it, just figured I'd let you know. -- 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