On 6/15/26 17:27, Vlastimil Babka (SUSE) wrote:

On 6/15/26 17:18, David Hildenbrand (Arm) wrote:

quoted

On 6/15/26 16:38, Vlastimil Babka (SUSE) wrote:

quoted

I think the memalloc approach is dangerous due to unexpected nesting. There
might be nested page allocations in page allocation itself (due to some
debugging option). But also interrupts do not change what "current" points
to. Suddenly those could start requesting folios and/or private nodes and be
surprised, I'm afraid.

Yeah, we'd need some way to distinguish the main allocation from these other
(nested) allocations.

That goes against the very principle of scopes. And I don't see how, except
via a ... flag to the main allocation :D

Unless we teach the handful of debug callpaths to set a custom context. Have
some memalloc_context_save/restore.

I'd assume that the number of such nested allocations we can trigger from the
buddy (through some callbacks like kasan and such) should be rather limited.

I also wonder for a second whether we could use of the _noprof vs. !_noprof
mechanism.

Essentially, calling a !_noprof variant ("external allocation interface") could
mean "save/restore folio allocation". Just a thought.

-- 
Cheers,

David