LKML Archive on
help / color / mirror / Atom feed
From: "tip-bot2 for Sebastian Andrzej Siewior" <>
Cc: Sebastian Andrzej Siewior <>,
	"Peter Zijlstra (Intel)" <>,,
Subject: [tip: sched/urgent] sched: Fix get_push_task() vs migrate_disable()
Date: Thu, 26 Aug 2021 17:07:45 -0000	[thread overview]
Message-ID: <162999766586.25758.3269412583101742484.tip-bot2@tip-bot2> (raw)
In-Reply-To: <>

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     e681dcbaa4b284454fecd09617f8b24231448446
Author:        Sebastian Andrzej Siewior <>
AuthorDate:    Thu, 26 Aug 2021 15:37:38 +02:00
Committer:     Peter Zijlstra <>
CommitterDate: Thu, 26 Aug 2021 19:02:00 +02:00

sched: Fix get_push_task() vs migrate_disable()

push_rt_task() attempts to move the currently running task away if the
next runnable task has migration disabled and therefore is pinned on the
current CPU.

The current task is retrieved via get_push_task() which only checks for
nr_cpus_allowed == 1, but does not check whether the task has migration
disabled and therefore cannot be moved either. The consequence is a
pointless invocation of the migration thread which correctly observes
that the task cannot be moved.

Return NULL if the task has migration disabled and cannot be moved to
another CPU.

Fixes: a7c81556ec4d3 ("sched: Fix migrate_disable() vs rt/dl balancing")
Signed-off-by: Sebastian Andrzej Siewior <>
Signed-off-by: Peter Zijlstra (Intel) <>
 kernel/sched/sched.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index da4295f..ddefb04 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2255,6 +2255,9 @@ static inline struct task_struct *get_push_task(struct rq *rq)
 	if (p->nr_cpus_allowed == 1)
 		return NULL;
+	if (p->migration_disabled)
+		return NULL;
 	rq->push_busy = true;
 	return get_task_struct(p);

      parent reply	other threads:[~2021-08-26 17:07 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-26 13:37 [PATCH] " Sebastian Andrzej Siewior
2021-08-26 16:24 ` Tao Zhou
2021-08-26 19:38   ` Thomas Gleixner
2021-08-26 22:53     ` Tao Zhou
2021-08-26 16:56 ` Peter Zijlstra
2021-08-26 17:07 ` tip-bot2 for Sebastian Andrzej Siewior [this message]

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:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=162999766586.25758.3269412583101742484.tip-bot2@tip-bot2 \ \ \ \ \ \ \
    --subject='Re: [tip: sched/urgent] sched: Fix get_push_task() vs migrate_disable()' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

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).