Re: [LSF/MM/BPF TOPIC] Discussion: Targeted memory allocation via debugfs

["David Hildenbrand (Arm)" <david@kernel.org>]

On 2/27/26 03:42, Juan Yescas wrote:
> Hi LSF MM organizers

Hi,

I'm late ...

> 
> I would like to propose a discussion on improving our ability to
> reproduce complex memory allocation and reclaim scenarios, and solicit
> feedback on a debugfs-based testing interface to help trigger these
> edge cases.
> 
> == The Problem ==
> 
> We frequently encounter complex memory management issues in the wild, including:
> 
> - CMA allocation failures due to pinned MIGRATE_MOVABLE pages.
> - Page migration and compaction failing during reclaim.
> - Excessive reclaim loops triggered by specific workloads.
> - OOM kills.
> 
> Reproducing these specific memory states for debugging is currently
> cumbersome. For instance, consuming most of the available
> MIGRATE_MOVABLE memory, or forcing MIGRATE_UNMOVABLE allocations
> specifically from Node 1 and Zone DMA directly from userspace,
> requires writing custom kernel modules or relying on unreliable
> userspace memory pressure tactics.

I'm wondering whether an OOT module for this purpose would be sufficient?

IOW, do we really have to have this in the upstream kernel, or could we
have a public OOT module to perform these allocations?

Then, there are no worries about API/Extensibility etc.

Or would you want to fire up this debugging on a production kernel? I
would assume now.

-- 
Cheers,

David