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 ... -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
