On Wed, Sep 30, 2020 at 7:48 AM Dave Hansen <dave.han...@intel.com> wrote: > > On 9/30/20 7:42 AM, Liang, Kan wrote: > >> When I tested on my kernel, it panicked because I suspect > >> current->active_mm could be NULL. Adding a check for NULL avoided the > >> problem. But I suspect this is not the correct solution. > > > > I guess the NULL active_mm should be a rare case. If so, I think it's > > not bad to add a check and return 0 page size. > > I think it would be best to understand why ->active_mm is NULL instead > of just papering over the problem. If it is papered over, and this is > common, you might end up effectively turning off your shiny new feature > inadvertently.
I tried that on a backport of the patch to an older kernel. Maybe the behavior of active_mm has change compared to tip.git. I will try again with tip.git.
