From: Kinsey Ho <kinseyho@google.com>
To: "Michal Koutný" <mkoutny@suse.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: Fri, 16 Aug 2024 12:27:27 -0400 [thread overview]
Message-ID: <CAF6N3nXmQ=+j5VNf16KL6Ma8RaO0o-Nv=C7reJKQOzdpHzWOsg@mail.gmail.com> (raw)
In-Reply-To: <zh4ccaje54qbi6a62rvlhclysyaymw76bona4qtd53k4ogjuv7@tppv2q4zgyjk>
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.
In that case, memcg won't be assigned and could be left with a
previous, invalid value. By moving the assignment out, it ensures that
memcg is a valid value.
Best,
Kinsey
next prev parent reply other threads:[~2024-08-16 16:27 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 [this message]
2024-08-20 11:59 ` Michal Koutný
2024-08-13 20:47 ` [PATCH mm-unstable v2 5/5] mm: clean up mem_cgroup_iter() Kinsey Ho
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAF6N3nXmQ=+j5VNf16KL6Ma8RaO0o-Nv=C7reJKQOzdpHzWOsg@mail.gmail.com' \
--to=kinseyho@google.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lizefan.x@bytedance.com \
--cc=mhocko@kernel.org \
--cc=mkoutny@suse.com \
--cc=muchun.song@linux.dev \
--cc=roman.gushchin@linux.dev \
--cc=shakeel.butt@linux.dev \
--cc=tj@kernel.org \
--cc=yosryahmed@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox