From: tip-bot for Peter Zijlstra <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, sachinp@linux.vnet.ibm.com,
mpe@ellerman.id.au, bp@suse.de, torvalds@linux-foundation.org,
matt@codeblueprint.co.uk, mingo@kernel.org, efault@gmx.de,
hpa@zytor.com, zwisler@gmail.com, tglx@linutronix.de,
peterz@infradead.org
Subject: [tip:sched/urgent] sched/core: Fix update_rq_clock() splat on hotplug (and suspend/resume)
Date: Fri, 24 Feb 2017 01:16:05 -0800 [thread overview]
Message-ID: <tip-8cb68b343a66cf19834472012590490d34d31703@git.kernel.org> (raw)
In-Reply-To: <20170202155506.GX6515@twins.programming.kicks-ass.net>
Commit-ID: 8cb68b343a66cf19834472012590490d34d31703
Gitweb: http://git.kernel.org/tip/8cb68b343a66cf19834472012590490d34d31703
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Thu, 2 Feb 2017 16:55:06 +0100
Committer: Ingo Molnar <mingo@kernel.org>
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@linux-foundation.org>
Tested-by: Mike Galbraith <efault@gmx.de>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ross Zwisler <zwisler@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4d25b35ea372 ("sched/fair: Restore previous rq_flags when migrating tasks in hotplug")
Link: http://lkml.kernel.org/r/20170202155506.GX6515@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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);
}
prev parent reply other threads:[~2017-02-24 9:44 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 13:38 [PATCH v2 0/7] sched: Diagnostic checks for missing rq clock updates Matt Fleming
2016-09-21 13:38 ` [PATCH v2 1/7] sched/fair: Update the rq clock before detaching tasks Matt Fleming
2016-10-03 12:49 ` Peter Zijlstra
2016-10-03 14:37 ` Matt Fleming
2016-10-03 14:42 ` Peter Zijlstra
2016-09-21 13:38 ` [PATCH v2 2/7] sched/fair: Update rq clock before waking up new task Matt Fleming
2016-09-21 13:38 ` [PATCH v2 3/7] sched/fair: Update rq clock in task_hot() Matt Fleming
2016-09-21 13:38 ` [PATCH v2 4/7] sched: Add wrappers for lockdep_(un)pin_lock() Matt Fleming
2017-01-14 12:40 ` [tip:sched/core] sched/core: " tip-bot for Matt Fleming
2016-09-21 13:38 ` [PATCH v2 5/7] sched/core: Reset RQCF_ACT_SKIP before unpinning rq->lock Matt Fleming
2017-01-14 12:41 ` [tip:sched/core] " tip-bot for Matt Fleming
2016-09-21 13:38 ` [PATCH v2 6/7] sched/fair: Push rq lock pin/unpin into idle_balance() Matt Fleming
2017-01-14 12:41 ` [tip:sched/core] " tip-bot for Matt Fleming
2016-09-21 13:38 ` [PATCH v2 7/7] sched/core: Add debug code to catch missing update_rq_clock() Matt Fleming
2016-09-21 15:58 ` Petr Mladek
2016-09-21 19:08 ` Matt Fleming
2016-09-21 19:46 ` Thomas Gleixner
2016-09-22 0:44 ` Sergey Senozhatsky
2016-09-22 8:04 ` Peter Zijlstra
2016-09-22 8:36 ` Jan Kara
2016-09-22 9:39 ` Peter Zijlstra
2016-09-22 10:17 ` Peter Zijlstra
2017-01-14 12:44 ` [tip:sched/core] sched/core: Add debugging code to catch missing update_rq_clock() calls tip-bot for Matt Fleming
[not found] ` <87tw8gutp6.fsf@concordia.ellerman.id.au>
2017-01-30 21:34 ` Matt Fleming
2017-01-31 8:35 ` Michael Ellerman
2017-01-31 11:00 ` Sachin Sant
2017-01-31 11:48 ` Mike Galbraith
2017-01-31 17:22 ` Ross Zwisler
2017-02-02 15:55 ` Peter Zijlstra
2017-02-02 22:01 ` Matt Fleming
2017-02-03 3:05 ` Mike Galbraith
2017-02-03 4:33 ` Sachin Sant
2017-02-03 8:53 ` Peter Zijlstra
2017-02-03 12:59 ` Mike Galbraith
2017-02-03 13:37 ` Peter Zijlstra
2017-02-03 13:52 ` Mike Galbraith
2017-02-03 15:44 ` Paul E. McKenney
2017-02-03 15:54 ` Paul E. McKenney
2017-02-06 6:23 ` Sachin Sant
2017-02-06 15:10 ` Paul E. McKenney
2017-02-06 15:14 ` Paul E. McKenney
2017-02-03 13:04 ` Borislav Petkov
2017-02-22 9:03 ` Wanpeng Li
2017-02-24 9:16 ` tip-bot for Peter Zijlstra [this message]
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