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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aK28BEMMelOAMi5U@devbig569.cln6.facebook.com>
Date: Tue, 26 Aug 2025 06:52:04 -0700
From: Yueyang Pan <pyyjason@...il.com>
To: Shakeel Butt <shakeel.butt@...ux.dev>
Cc: Suren Baghdasaryan <surenb@...gle.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 02:26:42PM -0700, Shakeel Butt wrote:
> On Thu, Aug 21, 2025 at 01:00:36PM -0700, Suren Baghdasaryan wrote:
> > 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.
> 
> Thanks for the info. Pan, will having memcg info along with allocation
> profile help your use-case? (Though adding that might not be easy or
> cheaper)

Yeah I have been thinking about it with eBPF hooks but it is going to be a long 
term effort as we need to measure the overhead. Now the way memory profiling is 
implemented incur almost "zero" overhead.