Re: Disabling CONFIG_COMPACTION

[Mike Rapoport <rppt@kernel.org>]

Hi,

On Mon, May 15, 2023 at 08:44:30AM +0000, Pratoussy, Martin (GE Vernova) wrote:
> Hello,
> 
> We are facing an issue regarding Linux kernel 5.10.153. When we try to
> allocate huge amount of memory, we eventually run prematurely out of
> memory.  The bug has been discovered as follows: although "free" and
> "top" commands would show 40 MB of free memory, sending a 32 MB file
> through SFTP into RAM cache will lead to an OOM error before finishing
> the transfer.
> It has been noted that the command "echo 1 > /prox/sys/vm/compact_memory"
> leads into the very same behavior of the kernel. Disabling
> CONFIG_COMPACTION is surprisingly resolving the allocation issue and we
> are trying to understand why.
> 
> You will find below more information about the error we are facing:
> 
>   *   Architecture: Nios2
>   *   Total RAM size: 64 MB
>   *   Available RAM size when error occurs: ~17MB
>   *   Error message: "Huh VM_FAULT_OOM leaked out to the #PF handler. Retrying PF"
> 
> Would you have any idea of what is happening?

Even without digging into the actual reason for OOM, it makes perfect sense
to disable compaction on your system.
 
> You will find attached the .config of our kernel.
> 
> Best regards,
> 
> Martin Pratoussy
> Embedded software engineer apprentice - Electronics & High Voltage Digital, Grid Solutions
> GE Renewable
> M +33 (0)7 82 54 60 81
> www.gegridsolutions.com<http://www.gegridsolutions.com>
> 21, Rue Cyprian | 69100 Villeurbanne  | France
> 



-- 
Sincerely yours,
Mike.