On Tue, 27 Aug 2024 at 00:10, Vlastimil Babka [off-list ref] wrote:

Right now we give the WARN_ON_ONCE() (for !can_direct_reclaim) only when
we're about to actually return NULL, so the memory has to be depleted
already. To make it easier to find the offenders much more reliably, we
should consider doing it sooner, but also not add unnecessary overhead to
allocator fastpaths just because of the potentially buggy users.

Ack. Sounds like a sane model to me. And I agree that
__alloc_pages_slowpath() is likely a reasonable middle path between
"catch misuses, but don't put it in the hotpath".

               Linus