Re: Question Regarding [PATCH 098/167] in the 5.15 real-time patchset

Re: Question Regarding [PATCH 098/167] in the 5.15 real-time patchset

[Clark Williams]

I know we've had latency issues in the past with memory cgroups.

If there is a change in behavior in 5.16rt+ we can consider
backporting down to 5.15-rt

Clark

On Wed, Jul 6, 2022 at 8:25 PM Joseph Salisbury
<joseph.salisbury@canonical.com> wrote:
>
> Hello,
>
> An end user reported a bug[1] when attempting to use an Ubuntu kernel with the 5.15 real-time patches applied.  The user reports an issue with missing cg memory when Kubernetes is used with the 5.15 patchset.
>
> After an investigation, it was found the issue is happens if the CONFIG_MEMCG config is not enabled.  That config is usually enabled for the generic Ubuntu kernel.  However, the config is disabled by the following patch in the 5.15 real-time patch set:
>
> [PATCH 098/167] mm/memcontrol: Disable on PREEMPT_RT
>
> I don't see this patch in the 5.16 and newer patch sets.  Is there a fix in mainline or in the newer 5.16 patches that allows the 'mm/memcontrol: Disable on PREEMPT_RT' patch to be dropped?  If so, I could assist with backporting the fix to 5.15 and older.
>
> Thanks in advance!
>
> Joe
>
>
>
> [0] https://bugs.launchpad.net/ubuntu-realtime/+bug/1978814
>
>
>

Question Regarding [PATCH 098/167] in the 5.15 real-time patchset

[Joseph Salisbury]

Hello,

An end user reported a bug[1] when attempting to use an Ubuntu kernel 
with the 5.15 real-time patches applied.  The user reports an issue with 
missing cg memory when Kubernetes is used with the 5.15 patchset.

After an investigation, it was found the issue is happens if the 
CONFIG_MEMCG config is not enabled.  That config is usually enabled for 
the generic Ubuntu kernel.  However, the config is disabled by the 
following patch in the 5.15 real-time patch set:

[PATCH 098/167] mm/memcontrol: Disable on PREEMPT_RT

I don't see this patch in the 5.16 and newer patch sets.  Is there a fix 
in mainline or in the newer 5.16 patches that allows the 'mm/memcontrol: 
Disable on PREEMPT_RT' patch to be dropped?  If so, I could assist with 
backporting the fix to 5.15 and older.

Thanks in advance!

Joe


[0] https://bugs.launchpad.net/ubuntu-realtime/+bug/1978814