Re: [PATCH 0/8] lockdep: change 5 graph-db arrays to AofAs, fill from memblock pool

[jim . cromie]

On Thu, Aug 27, 2026 at 12:46 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Wed, Aug 26, 2026 at 09:58:32PM -0600, Jim Cromie wrote:
> > Lockdep cannot rely upon any other subsystem that uses locks, so since
> > inception, its graph-db has been stored in static arrays, pinning ~10
> > MB in .bss. This is a hardcoded compromise between embedded and
> > enterprise hardware.
> >
> > However, if it acts early, lockdep can pre-allocate a pool of slabs
> > from memblock_alloc(), enough for its lifetime of anticipated workloads.
> > Then it can allocate them as needed to provide new segments/slabs to
> > the graph-db.
> >
>
> Why? I really don't understand why. Who cares about this bss stuff.

I thought embedded folk might value 10mb less bss ?
Or have they stopped using lockdep already, for size or other reasons.

How about OOM, when kernel needs mem,
or lockdep debug-off, when the slabs tied up in the graph-db could be returned

do these not tip the scales ?