On Sun, Jan 26, 2014 at 11:00:52AM -0800, Ben Widawsky wrote: > On Sun, Jan 26, 2014 at 10:07:45AM +0000, Chris Wilson wrote: > > On Sun, Jan 26, 2014 at 11:01:50AM +0100, Daniel Vetter wrote: > > > On Sun, Jan 26, 2014 at 09:57:08AM +0000, Chris Wilson wrote: > > > > On Sun, Jan 26, 2014 at 10:17:57AM +0100, Daniel Vetter wrote: > > > > > On Sun, Jan 26, 2014 at 6:49 AM, Ben Widawsky <b...@bwidawsk.net> > > > > > wrote: > > > > > > On Sat, Jan 25, 2014 at 09:28:24PM +0100, Daniel Vetter wrote: > > > > > >> On Thu, Jan 23, 2014 at 07:21:10PM -0800, Ben Widawsky wrote: > > > > > >> > DRM gets very mad when you request an object which occupies a > > > > > >> > partial > > > > > >> > page. As a DRM driver, i915 never really wants to anger DRM, and > > > > > >> > would > > > > > >> > always just want the rounding done for us. > > > > > >> > > > > > > >> > Signed-off-by: Ben Widawsky <b...@bwidawsk.net> > > > > > >> > --- > > > > > >> > drivers/gpu/drm/i915/i915_gem.c | 2 ++ > > > > > >> > 1 file changed, 2 insertions(+) > > > > > >> > > > > > > >> > diff --git a/drivers/gpu/drm/i915/i915_gem.c > > > > > >> > b/drivers/gpu/drm/i915/i915_gem.c > > > > > >> > index 024e454..8cd1134 100644 > > > > > >> > --- a/drivers/gpu/drm/i915/i915_gem.c > > > > > >> > +++ b/drivers/gpu/drm/i915/i915_gem.c > > > > > >> > @@ -4168,6 +4168,8 @@ struct drm_i915_gem_object > > > > > >> > *i915_gem_alloc_object(struct drm_device *dev, > > > > > >> > struct address_space *mapping; > > > > > >> > gfp_t mask; > > > > > >> > > > > > > >> > + size = round_up(size, PAGE_SIZE); > > > > > >> > + > > > > > >> > > > > > >> Nope, if there's some code that doesn't do page-aligend bo > > > > > >> allocations it > > > > > >> needs to be fixed there. If you want throw a WARN_ON and early > > > > > >> return in > > > > > >> here. > > > > > >> -Daniel > > > > > > > > > > > > Why? > > > > > > > > > > Because allocating a non-page aligned gem bo is a bug. All current > > > > > in-kernel allocations are already aligned. I've thought that we also > > > > > reject unaligned request from userspace but apparently we help out > > > > > since forever (i.e. gem was merged). Might be worth a shot to turn > > > > > that into an -EINVAL if libdrm does the right rounding ... > > > > > > > > We already have an -EINVAL guard on our create ioctl(s). > > > > > > Only for size == 0, not for non-aligned size, at least afaics (no coffee > > > yet ...). > > > > The lack of caffeine was mine. I say if (blah(PAGE_SIZE)) return -EINVAL > > and was happy. > > > > But as it happens it still implies that the BUG_ON in drm/drm_gem.c is > > relevant as is and we shouldn't be papering over it. > > -Chris > > > > I was referring to internal, driver callers. If all internal callers > round up, we may as well do it for them. If the earlier assertion is > that we block bad sizes already at the IOCTL hanlder... then what's the > problem again?
create2_ioctl should imo reject non-page-aligned requests. I guess we could dig through libdrm history and check whether that's also possible for the current create ioctl. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx
