linux-kernel - Re: [RFC 0/1] Try to add memory allocation info for cgroup oom kill

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Message-ID: <CAJuCfpFKNQrjtoctVt0N=r1cABeyPjpwrzP6M=OTpp1Rq_0QaQ@mail.gmail.com>
Date: Thu, 21 Aug 2025 13:00:36 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Shakeel Butt <shakeel.butt@...ux.dev>
Cc: Yueyang Pan <pyyjason@...il.com>, Kent Overstreet <kent.overstreet@...ux.dev>, 
	Usama Arif <usamaarif642@...il.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC 0/1] Try to add memory allocation info for cgroup oom kill

On Thu, Aug 21, 2025 at 12:53 PM Shakeel Butt <shakeel.butt@...ux.dev> wrote:
>
> On Thu, Aug 21, 2025 at 12:18:00PM -0700, Yueyang Pan wrote:
> > On Thu, Aug 21, 2025 at 11:35:19AM -0700, Shakeel Butt wrote:
> > > On Thu, Aug 14, 2025 at 10:11:56AM -0700, Yueyang Pan wrote:
> > > > Right now in the oom_kill_process if the oom is because of the cgroup
> > > > limit, we won't get memory allocation infomation. In some cases, we
> > > > can have a large cgroup workload running which dominates the machine.
> > > > The reason using cgroup is to leave some resource for system. When this
> > > > cgroup is killed, we would also like to have some memory allocation
> > > > information for the whole server as well. This is reason behind this
> > > > mini change. Is it an acceptable thing to do? Will it be too much
> > > > information for people? I am happy with any suggestions!
> > >
> > > For a single patch, it is better to have all the context in the patch
> > > and there is no need for cover letter.
> >
> > Thanks for your suggestion Shakeel! I will change this in the next version.
> >
> > >
> > > What exact information you want on the memcg oom that will be helpful
> > > for the users in general? You mentioned memory allocation information,
> > > can you please elaborate a bit more.
> > >
> >
> > As in my reply to Suren, I was thinking the system-wide memory usage info
> > provided by show_free_pages and memory allocation profiling info can help
> > us debug cgoom by comparing them with historical data. What is your take on
> > this?
> >
>
> I am not really sure about show_free_areas(). More specifically how the
> historical data diff will be useful for a memcg oom. If you have a
> concrete example, please give one. For memory allocation profiling, is
> it possible to filter for the given memcg? Do we save memcg information
> in the memory allocation profiling?

No, memory allocation profiling is not cgroup-aware. It tracks
allocations and their code locations but no other context.