On Wed, Aug 17, 2016 at 7:40 AM, Vaishali Thakkar <vaishali.thakkar at oracle.com> wrote: > Hello, > > I was wondering about the call to copy_from_user in function > submit_lookup_objects for drive > /gpu/drm/msm/msm_gem_submit.c It calls copy_from_user[1] in a spin_lock, > which is not normally > allowed, due to the possibility of a deadlock. > > Is there some reason that I am overlooking why it is OK in this case? Is > there some code in the > same file which ensures that page fault will not occur when we are calling > the function holding > spin_lock?
hmm, probably just that it isn't typical to use a swap file on these devices (and that lockdep/etc doesn't warn about it).. I guess we probably need some sort of slow-path where we drop the lock and try again in case there would be a fault.. BR, -R > Thank you. > > [1] > http://lxr.free-electrons.com/source/drivers/gpu/drm/msm/msm_gem_submit.c#L85 > > -- > Vaishali
