From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [Intel-gfx] [PATCH 1/3] mm: Check if mmu notifier callbacks are allowed to fail Date: Fri, 23 Nov 2018 12:14:28 +0100 Message-ID: <20181123111428.GF8625@dhcp22.suse.cz> References: <20181122165106.18238-1-daniel.vetter@ffwll.ch> <20181122165106.18238-2-daniel.vetter@ffwll.ch> <154290561362.11623.15299444358726283678@skylake-alporthouse-com> <20181123084934.GI4266@phenom.ffwll.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20181123084934.GI4266@phenom.ffwll.local> Sender: linux-kernel-owner@vger.kernel.org To: Daniel Vetter Cc: Chris Wilson , Daniel Vetter , LKML , Daniel Vetter , Intel Graphics Development , DRI Development , Linux MM , =?iso-8859-1?B?Suly9G1l?= Glisse , David Rientjes , Paolo Bonzini , Andrew Morton , Christian =?iso-8859-1?Q?K=F6nig?= List-Id: intel-gfx@lists.freedesktop.org On Fri 23-11-18 09:49:34, Daniel Vetter wrote: > On Thu, Nov 22, 2018 at 04:53:34PM +0000, Chris Wilson wrote: > > Quoting Daniel Vetter (2018-11-22 16:51:04) > > > Just a bit of paranoia, since if we start pushing this deep into > > > callchains it's hard to spot all places where an mmu notifier > > > implementation might fail when it's not allowed to. > > > > Most callers could handle the failure correctly. It looks like the > > failure was not propagated for convenience. > > I have no idea whether the mm is semantically ok if pte shootdown doesn't > work for all sorts of strange reasons. From the commit that introduced the > error code it souded like this was very much only ok in the limited case > of an already killed process, in the oom killer path, where it's really > only about trying to free any kind of memory. And where the process is > gone already, so semantics of what exactly happens don't matter that much > anymore. Yes this was indeed the case. There is still the exit path which would do the rest of the work so we are not leaving anything behind. -- Michal Hocko SUSE Labs