linux-kernel - [PATCH 0/2] sched: Address idle task vs pcpu kthread checks

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Message-Id: <20210510151024.2448573-1-valentin.schneider@arm.com>
Date:   Mon, 10 May 2021 16:10:22 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, peterz@...radead.org, tglx@...utronix.de,
        bristot@...hat.com, yejune.deng@...il.com
Subject: [PATCH 0/2] sched: Address idle task vs pcpu kthread checks

Commit

  5ba2ffba13a1 ("sched: Fix CPU hotplug / tighten is_per_cpu_kthread()")

had to special-case the idle task when checking for per-CPU kthreads. This is
due to the idle task not having its own struct kthread, which is where we'd
store KTHREAD_IS_PER_CPU.

>From staring at Yejune's recent patch [1], it turns out the idle task is also
missing PF_NO_SETAFFINITY.

Patch 1 cleans this up, patch 2 is Yejune's v1 which depends on it.


Note: I remember seeing some patch(es) from Peter tackling this exact
problem, but I couldn't find them again.

[1]: http://lore.kernel.org/r/1620458722-13026-1-git-send-email-yejunedeng@gmail.com

Cheers,
Valentin

Valentin Schneider (1):
  sched: Make the idle task quack like a per-CPU kthread

Yejune Deng (1):
  lib/smp_processor_id: Use is_percpu_thread() instead of
    nr_cpus_allowed

 include/linux/kthread.h |  2 ++
 kernel/kthread.c        | 30 ++++++++++++++++++------------
 kernel/sched/core.c     | 21 +++++++++++++++------
 lib/smp_processor_id.c  |  6 +-----
 4 files changed, 36 insertions(+), 23 deletions(-)

--
2.25.1