From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: xiaolong.ye@intel.com, frederic@kernel.org, tglx@linutronix.de,
cmetcalf@mellanox.com, cl@linux.com,
torvalds@linux-foundation.org, lcapitulino@redhat.com,
efault@gmx.de, peterz@infradead.org, riel@redhat.com,
kernellwp@gmail.com, mingo@kernel.org, john.stultz@linaro.org
Subject: [PATCH] sched/isolation: Make NO_HZ_FULL select CPU_ISOLATION
Date: Thu, 30 Nov 2017 12:20:46 -0800 [thread overview]
Message-ID: <20171130202046.GA27138@linux.vnet.ibm.com> (raw)
Commit 5c4991e24c69 ("sched/isolation: Split out new
CONFIG_CPU_ISOLATION=y config from CONFIG_NO_HZ_FULL") can result in RCU
CPU stall warnings when running rcutorture with CONFIG_NO_HZ_FULL_ALL=y
and CONFIG_CPU_ISOLATION=n. These warnings are caused by RCU's
grace-period kthreads sleeping for a few jiffies, but never being
awakened:
[ 116.353432] rcu_preempt kthread starved for 9974 jiffies! g4294967208
+c4294967207 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x402 ->cpu=0
[ 116.355517] rcu_preempt I 7464 8 2 0x80000000
[ 116.356543] Call Trace:
[ 116.357008] __schedule+0x493/0x620
[ 116.357682] schedule+0x24/0x40
[ 116.358291] schedule_timeout+0x330/0x3b0
[ 116.359024] ? preempt_count_sub+0xea/0x140
[ 116.359806] ? collect_expired_timers+0xb0/0xb0
[ 116.360660] rcu_gp_kthread+0x6bf/0xef0
This commit therefore makes NO_HZ_FULL select CPU_ISOLATION, which
prevents this behavior and seems like it was the original intention in
any case.
Fixes: 5c4991e24c69 ("sched/isolation: Split out new CONFIG_CPU_ISOLATION=y config from CONFIG_NO_HZ_FULL")
Link: https://lkml.kernel.org/r/20171126084203.GE21779@yexl-desktop
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index e776fc8cc1df..f6b5f19223d6 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -95,6 +95,7 @@ config NO_HZ_FULL
select RCU_NOCB_CPU
select VIRT_CPU_ACCOUNTING_GEN
select IRQ_WORK
+ select CPU_ISOLATION
help
Adaptively try to shutdown the tick whenever possible, even when
the CPU is running tasks. Typically this requires running a single
next reply other threads:[~2017-11-30 20:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-30 20:20 Paul E. McKenney [this message]
2017-12-02 13:59 ` [PATCH] sched/isolation: Make NO_HZ_FULL select CPU_ISOLATION Frederic Weisbecker
2017-12-02 19:24 ` Paul E. McKenney
2017-12-04 15:53 ` Frederic Weisbecker
2017-12-04 17:16 ` Paul E. McKenney
2017-12-07 16:14 ` Frederic Weisbecker
2017-12-07 17:29 ` Paul E. McKenney
2017-12-09 13:09 ` Frederic Weisbecker
2017-12-09 18:09 ` Paul E. McKenney
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=20171130202046.GA27138@linux.vnet.ibm.com \
--to=paulmck@linux.vnet.ibm.com \
--cc=cl@linux.com \
--cc=cmetcalf@mellanox.com \
--cc=efault@gmx.de \
--cc=frederic@kernel.org \
--cc=john.stultz@linaro.org \
--cc=kernellwp@gmail.com \
--cc=lcapitulino@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=riel@redhat.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=xiaolong.ye@intel.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;
as well as URLs for NNTP newsgroup(s).