linux-kselftest.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Michal Koutný" <mkoutny@suse.com>
To: Waiman Long <longman@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>, Shuah Khan <shuah@kernel.org>,
	cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <guro@fb.com>, Phil Auld <pauld@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH v9 3/7] cgroup/cpuset: Refining features and constraints of a partition
Date: Wed, 15 Dec 2021 15:49:44 +0100	[thread overview]
Message-ID: <20211215144944.GE16798@blackbody.suse.cz> (raw)
In-Reply-To: <20211205183220.818872-4-longman@redhat.com>

On Sun, Dec 05, 2021 at 01:32:16PM -0500, Waiman Long <longman@redhat.com> wrote:
> @@ -1455,34 +1450,16 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp)
>  			switch (parent->partition_root_state) {
> [...]
> -
>  			case PRS_ENABLED:
> -				if (update_parent_subparts_cpumask(cp, partcmd_update, NULL, tmp))
> -					update_tasks_cpumask(parent);
> +				update_parent = true;
> [...]
> +		if (update_parent) {
> +			if (update_parent_subparts_cpumask(cp, partcmd_update, NULL, tmp))
> +				update_tasks_cpumask(parent);
> +			/*
> +			 * The cpuset partition_root_state may be changed
> +			 * to PRS_ERROR. Capture it.
> +			 */
> +			new_prs = cp->partition_root_state;
> +		}

IIUC, this ensures that when a parent becomes partition root again, this
would propagate downwards to invalidated children. 

However, the documentation says:

> +       Changing a partition root (valid or invalid) to "member" is
> +       always allowed.  If there are child partition roots underneath
> +       it, they will become invalid and unrecoverable.  So care must
> +       be taken to double check for this condition before disabling
> +       a partition root.

I.e. it suggests a child can be trapped in the unrecoverable state (i.e.
not fixable by writing into cpuset.cpus.partition).
But this does not happen, right?

Michal

  reply	other threads:[~2021-12-15 14:49 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-05 18:32 [PATCH v9 0/7] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Waiman Long
2021-12-05 18:32 ` [PATCH v9 1/7] cgroup/cpuset: Don't let child cpusets restrict parent in default hierarchy Waiman Long
2021-12-13 20:41   ` Tejun Heo
2021-12-15 12:23     ` Michal Koutný
2021-12-15 17:59       ` Waiman Long
2021-12-17 15:48         ` [PATCH] cgroup/cpuset: Make child cpusets restrict parents on v1 hierarchy Michal Koutný
2021-12-17 16:34           ` Waiman Long
2022-01-12 21:25           ` Tejun Heo
2021-12-05 18:32 ` [PATCH v9 2/7] cgroup/cpuset: Allow no-task partition to have empty cpuset.cpus.effective Waiman Long
2021-12-13 20:45   ` Tejun Heo
2021-12-15  3:24     ` Waiman Long
2021-12-15 10:36       ` Michal Koutný
2021-12-05 18:32 ` [PATCH v9 3/7] cgroup/cpuset: Refining features and constraints of a partition Waiman Long
2021-12-15 14:49   ` Michal Koutný [this message]
2021-12-15 16:29     ` Waiman Long
2021-12-16  9:28       ` Michal Koutný
2021-12-05 18:32 ` [PATCH v9 4/7] cgroup/cpuset: Add a new isolated cpus.partition type Waiman Long
2022-01-12 15:21   ` Peter Zijlstra
2022-01-12 15:40     ` Waiman Long
2022-01-12 21:23       ` Tejun Heo
2021-12-05 18:32 ` [PATCH v9 5/7] cgroup/cpuset: Show invalid partition reason string Waiman Long
2021-12-05 18:32 ` [PATCH v9 6/7] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst Waiman Long
2021-12-13 21:00   ` Tejun Heo
2021-12-15 14:44     ` Michal Koutný
2021-12-15 18:16       ` Waiman Long
2021-12-15 18:35         ` Tejun Heo
2021-12-15 18:55           ` Waiman Long
2022-01-12 21:21             ` Tejun Heo
2021-12-05 18:32 ` [PATCH v9 7/7] kselftest/cgroup: Add cpuset v2 partition root state test Waiman Long
2021-12-09 15:39 ` [PATCH v9 0/7] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Waiman Long

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=20211215144944.GE16798@blackbody.suse.cz \
    --to=mkoutny@suse.com \
    --cc=akpm@linux-foundation.org \
    --cc=cgroups@vger.kernel.org \
    --cc=corbet@lwn.net \
    --cc=frederic@kernel.org \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=juri.lelli@redhat.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=lizefan.x@bytedance.com \
    --cc=longman@redhat.com \
    --cc=mtosatti@redhat.com \
    --cc=pauld@redhat.com \
    --cc=peterz@infradead.org \
    --cc=shuah@kernel.org \
    --cc=tj@kernel.org \
    /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;
as well as URLs for NNTP newsgroup(s).