Re: [RFC-PATCH 1/2] mm: Add __GFP_NO_LOCKS flag

Michal Hocko
2020-08-13T19:13:51Z

On Thu 13-08-20 20:31:21, Peter Zijlstra wrote:
> On Thu, Aug 13, 2020 at 09:29:04AM -0700, Paul E. McKenney wrote:
[...]
> > 3. Reusing existing GFP_ flags/values/whatever to communicate
> > the raw-context information that was to be communicated by
> > the new GFP_ flag.
> >
> > 4. Making lockdep forgive acquiring spinlocks while holding
> > raw spinlocks, but only in CONFIG_PREEMPT_NONE=y kernels.
> >
> > Am I missing anything?
>
> How would 4 solve anything?

Nothing on its own but along with http://lkml.kernel.org/r/20200813075027.GD9477@dhcp22.suse.cz
it would allow at least _some_ NOWAIT semantic for RT atomic contexts
and prevent from lockdep false positives for !RT trees.
--
Michal Hocko
SUSE Labs