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authorPeter Zijlstra <peterz@infradead.org>2017-05-24 08:52:02 +0200
committerIngo Molnar <mingo@kernel.org>2017-05-24 09:10:00 +0200
commit45aea321678856687927c53972321ebfab77759a (patch)
tree7e82415526d67107739c41076bc329e63d096c44 /kernel/sched/clock.c
parent5c3c2ea6887176c5ae812c9f0350ff65b10e9485 (diff)
downloadlinux-45aea321678856687927c53972321ebfab77759a.tar.bz2
sched/clock: Fix early boot preempt assumption in __set_sched_clock_stable()
The more strict early boot preemption warnings found that __set_sched_clock_stable() was incorrectly assuming we'd still be running on a single CPU: BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 caller is debug_smp_processor_id+0x1c/0x1e CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.12.0-rc2-00108-g1c3c5ea #1 Call Trace: dump_stack+0x110/0x192 check_preemption_disabled+0x10c/0x128 ? set_debug_rodata+0x25/0x25 debug_smp_processor_id+0x1c/0x1e sched_clock_init_late+0x27/0x87 [...] Fix it by disabling IRQs. Reported-by: kernel test robot <xiaolong.ye@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: lkp@01.org Cc: tipbuild@zytor.com Link: http://lkml.kernel.org/r/20170524065202.v25vyu7pvba5mhpd@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/clock.c')
-rw-r--r--kernel/sched/clock.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
index 1a0d389d2f2b..ca0f8fc945c6 100644
--- a/kernel/sched/clock.c
+++ b/kernel/sched/clock.c
@@ -133,12 +133,19 @@ static void __scd_stamp(struct sched_clock_data *scd)
static void __set_sched_clock_stable(void)
{
- struct sched_clock_data *scd = this_scd();
+ struct sched_clock_data *scd;
/*
+ * Since we're still unstable and the tick is already running, we have
+ * to disable IRQs in order to get a consistent scd->tick* reading.
+ */
+ local_irq_disable();
+ scd = this_scd();
+ /*
* Attempt to make the (initial) unstable->stable transition continuous.
*/
__sched_clock_offset = (scd->tick_gtod + __gtod_offset) - (scd->tick_raw);
+ local_irq_enable();
printk(KERN_INFO "sched_clock: Marking stable (%lld, %lld)->(%lld, %lld)\n",
scd->tick_gtod, __gtod_offset,