On Wed, Mar 15, 2017 at 11:46:24AM +0200, Mika Kuoppala wrote: > Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes: > > > kasan is very good at detecting use-after-free. However, our requests > > are allocated from a rcu-typesafe slab that is important for performance > > but makes kasan less effective. When enabling kasan we are intentionally > > looking for memory errors, disable the use of our caches to improve the > > likelihood of kasan spotting a bug. > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/i915/Kconfig.debug | 13 +++++++++++++ > > drivers/gpu/drm/i915/i915_gem.c | 11 +++++++++-- > > drivers/gpu/drm/i915/i915_gem_request.c | 25 ++++++++++++++++++++----- > > drivers/gpu/drm/i915/i915_vma.c | 15 ++++++++++++--- > > 4 files changed, 54 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug > > index e091809a9a9e..bd8e90e4dfb9 100644 > > --- a/drivers/gpu/drm/i915/Kconfig.debug > > +++ b/drivers/gpu/drm/i915/Kconfig.debug > > @@ -48,6 +48,19 @@ config DRM_I915_DEBUG_GEM > > > > If in doubt, say "N". > > > > +config DRM_I915_DEBUG_KASAN > > + bool "Insert extra checks when using KASAN" > > + default n > > + depends on DRM_I915_WERROR > > + depends on KASAN > > + help > > + Turns off use of kmem_caches to improve KASAN error detection, > > + and inserts extra santiy checks. > > s/santiy/sanity. > > Would i915.kmem_cache=0/1 be too costly? More of the principle. Having module options means somebody will enable it. Hiding it away underneath a bevy of expert config options makes it much less likely. CI basically have to do two runs for each option -- if we are using kasan, we want improved coverage, but we also need to test that the default configuration works. It's probably best just to teach kmem_cache itself to behave differently if it helps. I was just thinking fine-grained swapping of behaviour would be benificial. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
