On Tue, Dec 12, 2023 at 02:25:16PM -0800, Ricardo Neri wrote: > Before determining the validity of the last-level cache info, ensure that > it has been allocated. Simply checking for non-zero cache_leaves() is not > sufficient, as some architectures (e.g., Intel processors) have non-zero > cache_leaves() before allocation. > > Dereferencing NULL cacheinfo can occur in update_per_cpu_data_slice_size(). > This function iterates over all online CPUs. However, a CPU may have come > online recently, but its cacheinfo may not have been allocated yet. > > Cc: Andreas Herrmann <aherrmann@xxxxxxxx> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > Cc: Chen Yu <yu.c.chen@xxxxxxxxx> > Cc: Huang Ying <ying.huang@xxxxxxxxx> > Cc: Len Brown <len.brown@xxxxxxxxx> > Cc: Radu Rendec <rrendec@xxxxxxxxxx> > Cc: Pierre Gondois <Pierre.Gondois@xxxxxxx> > Cc: Pu Wen <puwen@xxxxxxxx> > Cc: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx> > Cc: Sudeep Holla <sudeep.holla@xxxxxxx> If you respin, you can address the below minor nit. I am fine as is as well. Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx> [...] > diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c > index f1e79263fe61..967c5cf3fb1d 100644 > --- a/drivers/base/cacheinfo.c > +++ b/drivers/base/cacheinfo.c > @@ -61,6 +61,9 @@ bool last_level_cache_is_valid(unsigned int cpu) > if (!cache_leaves(cpu)) > return false; > > + if (!per_cpu_cacheinfo(cpu)) > + return false; > + [nit] You can even combine this with above if condition. -- Regards, Sudeep
