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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-12-14 19:18:25 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-12-18 13:46:42 +0100 |
| commit | bf29cb238dc0656e6564b6a94bb82e11d2129437 (patch) | |
| tree | 258d36fa5a6ecf11eab88dbd1c6b7231a9087ec8 /kernel/time/Kconfig | |
| parent | 1291a0d5049dbc06baaaf66a9ff3f53db493b19b (diff) | |
| download | lwn-bf29cb238dc0656e6564b6a94bb82e11d2129437.tar.gz lwn-bf29cb238dc0656e6564b6a94bb82e11d2129437.zip | |
sched/isolation: Make CONFIG_NO_HZ_FULL select CONFIG_CPU_ISOLATION
CONFIG_NO_HZ_FULL doesn't make sense without CONFIG_CPU_ISOLATION. In
fact enabling the first without the second is a regression as nohz_full=
boot parameter gets silently ignored.
Besides this unnatural combination hangs RCU gp kthread when running
rcutorture for reasons that are not yet fully understood:
rcu_preempt kthread starved for 9974 jiffies! g4294967208
+c4294967207 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x402 ->cpu=0
rcu_preempt I 7464 8 2 0x80000000
Call Trace:
__schedule+0x493/0x620
schedule+0x24/0x40
schedule_timeout+0x330/0x3b0
? preempt_count_sub+0xea/0x140
? collect_expired_timers+0xb0/0xb0
rcu_gp_kthread+0x6bf/0xef0
This commit therefore makes NO_HZ_FULL select CPU_ISOLATION, which
prevents all these bad behaviours.
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: John Stultz <john.stultz@linaro.org>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <kernellwp@gmail.com>
Fixes: 5c4991e24c69 ("sched/isolation: Split out new CONFIG_CPU_ISOLATION=y config from CONFIG_NO_HZ_FULL")
Link: http://lkml.kernel.org/r/1513275507-29200-2-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/time/Kconfig')
| -rw-r--r-- | kernel/time/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
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 |