4.17-stable review patch. If anyone has any objections, please let me know.
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From: Sebastian Andrzej Siewior bigeasy@linutronix.de
[ Upstream commit 02acc80d19edb0d5684c997b2004ad19f9f5236e ]
try_to_wake_up() might invoke delayacct_blkio_end() while holding the pi_lock (which is a raw_spinlock_t). delayacct_blkio_end() acquires task_delay_info.lock which is a spinlock_t. This causes a might sleep splat on -RT where non raw spinlocks are converted to 'sleeping' spinlocks.
task_delay_info.lock is only held for a short amount of time so it's not a problem latency wise to make convert it to a raw spinlock.
Signed-off-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: Balbir Singh bsingharora@gmail.com Link: https://lkml.kernel.org/r/20180423161024.6710-1-bigeasy@linutronix.de Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/delayacct.h | 2 +- kernel/delayacct.c | 17 +++++++++-------- 2 files changed, 10 insertions(+), 9 deletions(-)
--- a/include/linux/delayacct.h +++ b/include/linux/delayacct.h @@ -29,7 +29,7 @@
#ifdef CONFIG_TASK_DELAY_ACCT struct task_delay_info { - spinlock_t lock; + raw_spinlock_t lock; unsigned int flags; /* Private per-task flags */
/* For each stat XXX, add following, aligned appropriately --- a/kernel/delayacct.c +++ b/kernel/delayacct.c @@ -44,23 +44,24 @@ void __delayacct_tsk_init(struct task_st { tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL); if (tsk->delays) - spin_lock_init(&tsk->delays->lock); + raw_spin_lock_init(&tsk->delays->lock); }
/* * Finish delay accounting for a statistic using its timestamps (@start), * accumalator (@total) and @count */ -static void delayacct_end(spinlock_t *lock, u64 *start, u64 *total, u32 *count) +static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, + u32 *count) { s64 ns = ktime_get_ns() - *start; unsigned long flags;
if (ns > 0) { - spin_lock_irqsave(lock, flags); + raw_spin_lock_irqsave(lock, flags); *total += ns; (*count)++; - spin_unlock_irqrestore(lock, flags); + raw_spin_unlock_irqrestore(lock, flags); } }
@@ -127,7 +128,7 @@ int __delayacct_add_tsk(struct taskstats
/* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
- spin_lock_irqsave(&tsk->delays->lock, flags); + raw_spin_lock_irqsave(&tsk->delays->lock, flags); tmp = d->blkio_delay_total + tsk->delays->blkio_delay; d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; tmp = d->swapin_delay_total + tsk->delays->swapin_delay; @@ -137,7 +138,7 @@ int __delayacct_add_tsk(struct taskstats d->blkio_count += tsk->delays->blkio_count; d->swapin_count += tsk->delays->swapin_count; d->freepages_count += tsk->delays->freepages_count; - spin_unlock_irqrestore(&tsk->delays->lock, flags); + raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
return 0; } @@ -147,10 +148,10 @@ __u64 __delayacct_blkio_ticks(struct tas __u64 ret; unsigned long flags;
- spin_lock_irqsave(&tsk->delays->lock, flags); + raw_spin_lock_irqsave(&tsk->delays->lock, flags); ret = nsec_to_clock_t(tsk->delays->blkio_delay + tsk->delays->swapin_delay); - spin_unlock_irqrestore(&tsk->delays->lock, flags); + raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); return ret; }