On Thu, 12 Sep 2013, Daniel Vetter wrote: > On Thu, Sep 12, 2013 at 9:58 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > > > >> On Thu, Sep 12, 2013 at 6:22 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > >> > If 'sane' userspace is never supposed to do this, then only insane > >> > userspace is going to hurt from this and that's a GOOD (tm) thing, > >> > right? ;-) > >> > >> Afaik sane userspace doesn't hit the _deadlock_ (or lifelock if we > >> have the set_need_resched in there). drm/i915 is a bit different since > >> we have just one lock, and so the same design would actually deadlock > >> even for sane userspace. But hitting contention there and yielding is > >> somewhat expected. Obviously shouldn't happen too often since it'll > >> hurt performance, with either blocking or the yield spinning loop. > > > > So this is actually a non priviledged DoS interface, right? > > I think for ttm drivers it's just execbuf being exploitable. But on > drm/i915 we've > had the same issue with the pwrite/pread ioctls, so a simple > glBufferData(glMap) kind of recursion from gl clients blew the kernel > to pieces ... And the only answer you folks came up with is set_need_resched() and yield()? Oh well.... Thanks, tglx _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
