Commit-ID: 8cb68b343a66cf19834472012590490d34d31703
Gitweb: http://git.kernel.org/tip/8cb68b343a66cf19834472012590490d34d31703
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Thu, 2 Feb 2017 16:55:06 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 24 Feb 2017 08:58:33 +0100
sched/core: Fix update_rq_clock() splat on hotplug (and suspend/resume)
The hotplug code still triggers the warning about using a stale
rq->clock value.
Fix things up to actually run update_rq_clock() in a place where we
record the 'UPDATED' flag, and then modify the annotation to retain
this flag over the rq->lock fiddling that happens as a result of
actually migrating all the tasks elsewhere.
Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Tested-by: Mike Galbraith <efault@xxxxxx>
Tested-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
Tested-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ross Zwisler <zwisler@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: 4d25b35ea372 ("sched/fair: Restore previous rq_flags when migrating tasks in hotplug")
Link: http://lkml.kernel.org/r/20170202155506.GX6515@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/core.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 34e2291..2d6e828 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5557,7 +5557,7 @@ static void migrate_tasks(struct rq *dead_rq)
{
struct rq *rq = dead_rq;
struct task_struct *next, *stop = rq->stop;
- struct rq_flags rf, old_rf;
+ struct rq_flags rf;
int dest_cpu;
/*
@@ -5576,7 +5576,9 @@ static void migrate_tasks(struct rq *dead_rq)
* class method both need to have an up-to-date
* value of rq->clock[_task]
*/
+ rq_pin_lock(rq, &rf);
update_rq_clock(rq);
+ rq_unpin_lock(rq, &rf);
for (;;) {
/*
@@ -5589,7 +5591,7 @@ static void migrate_tasks(struct rq *dead_rq)
/*
* pick_next_task() assumes pinned rq->lock:
*/
- rq_pin_lock(rq, &rf);
+ rq_repin_lock(rq, &rf);
next = pick_next_task(rq, &fake_task, &rf);
BUG_ON(!next);
next->sched_class->put_prev_task(rq, next);
@@ -5618,13 +5620,6 @@ static void migrate_tasks(struct rq *dead_rq)
continue;
}
- /*
- * __migrate_task() may return with a different
- * rq->lock held and a new cookie in 'rf', but we need
- * to preserve rf::clock_update_flags for 'dead_rq'.
- */
- old_rf = rf;
-
/* Find suitable destination for @next, with force if needed. */
dest_cpu = select_fallback_rq(dead_rq->cpu, next);
@@ -5633,7 +5628,6 @@ static void migrate_tasks(struct rq *dead_rq)
raw_spin_unlock(&rq->lock);
rq = dead_rq;
raw_spin_lock(&rq->lock);
- rf = old_rf;
}
raw_spin_unlock(&next->pi_lock);
}
--
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