From: "Michal Koutný" <mkoutny@suse.com>
To: Kinsey Ho <kinseyho@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org, Yosry Ahmed <yosryahmed@google.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Shakeel Butt <shakeel.butt@linux.dev>,
Muchun Song <muchun.song@linux.dev>, Tejun Heo <tj@kernel.org>,
Zefan Li <lizefan.x@bytedance.com>
Subject: Re: [PATCH mm-unstable v2 4/5] mm: restart if multiple traversals raced
Date: Tue, 20 Aug 2024 13:59:52 +0200 [thread overview]
Message-ID: <cjvz3rhv2wkoev3gwikb72x4ecwx76lpdvxvur3qdzpnykyvvb@k44wu2ec2htf> (raw)
In-Reply-To: <CAF6N3nXmQ=+j5VNf16KL6Ma8RaO0o-Nv=C7reJKQOzdpHzWOsg@mail.gmail.com>
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On Fri, Aug 16, 2024 at 12:27:27PM GMT, Kinsey Ho <kinseyho@google.com> wrote:
> Hi Michal,
>
> > I may be missing (literal) context but I'd suggest not moving the memcg
> > assignment and leverage
> > if (memcg != NULL)
> > css_put(memcg->css)
> > so that the is-root comparison needn't be repeated.
>
> I might also be misunderstanding you with respect to the is-root
> comparison – the reason the memcg assignment is moved is because it is
> possible that on the restart added in this patch, css could be NULL.
I've played with this applied up to 4/5 and I see more changes would be
needed to preserve the function. Please disregard my initial suggestion
':-)
Michal
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next prev parent reply other threads:[~2024-08-20 12:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-13 20:47 [PATCH mm-unstable v2 0/5] Improve mem_cgroup_iter() Kinsey Ho
2024-08-13 20:47 ` [PATCH mm-unstable v2 1/5] cgroup: clarify css sibling linkage is protected by cgroup_mutex or RCU Kinsey Ho
2024-08-14 9:00 ` Michal Koutný
2024-08-13 20:47 ` [PATCH mm-unstable v2 2/5] mm: don't hold css->refcnt during traversal Kinsey Ho
2024-08-14 9:00 ` Michal Koutný
2024-08-16 16:15 ` Kinsey Ho
2024-08-13 20:47 ` [PATCH mm-unstable v2 3/5] mm: increment gen # before restarting traversal Kinsey Ho
2024-08-13 20:47 ` [PATCH mm-unstable v2 4/5] mm: restart if multiple traversals raced Kinsey Ho
2024-08-14 9:00 ` Michal Koutný
2024-08-16 16:27 ` Kinsey Ho
2024-08-20 11:59 ` Michal Koutný [this message]
2024-08-13 20:47 ` [PATCH mm-unstable v2 5/5] mm: clean up mem_cgroup_iter() Kinsey Ho
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