[Devel] [PATCH vz8] kernel/sched/fair: Fix 'releasing a pinned lock'

[Andrey Ryabinin]

Lockdep complains that after rq_repin_lock() the lock wasn't unpinned
before rq->lock release.

------------[ cut here ]------------
releasing a pinned lock
WARNING: CPU: 0 PID: 24 at kernel/locking/lockdep.c:4271 lock_release+0x939/0xee0
Call Trace:
 _raw_spin_unlock+0x1c/0x30
 load_balance+0x1472/0x2e30
 pick_next_task_fair+0x62c/0x2300
 __schedule+0x481/0x1600
 schedule+0xbf/0x240
 worker_thread+0x1d5/0xb50
 kthread+0x30e/0x3d0
 ret_from_fork+0x3a/0x50

Add rq_unpin_lock(); call to fix this. Also for consistency use 'busiest'
instead of 'env.src_rq' which is the same.

https://jira.sw.ru/browse/PSBM-120800
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 kernel/sched/fair.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index fc87dee4fd0e..23a2f2452474 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9178,9 +9178,10 @@ static int load_balance(int this_cpu, struct rq *this_rq,
 			env.loop = 0;
 			local_irq_save(rf.flags);
 			double_rq_lock(env.dst_rq, busiest);
-			rq_repin_lock(env.src_rq, &rf);
+			rq_repin_lock(busiest, &rf);
 			update_rq_clock(env.dst_rq);
 			cur_ld_moved = ld_moved = move_task_groups(&env);
+			rq_unpin_lock(busiest, &rf);
 			double_rq_unlock(env.dst_rq, busiest);
 			local_irq_restore(rf.flags);
                 }
-- 
2.26.2