On Tue, Aug 05, 2014 at 12:33:16PM +0400, Ilya Dryomov wrote:
> On Mon, Aug 4, 2014 at 2:30 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > Hi,
> >
> > Ilya recently tripped over a nested sleep which made Ingo suggest we should
> > have debug checks for that. So I did some, see patch 7. Of course that
> > triggered a whole bunch of fail the instant I tried to boot my machine.
> >
> > With this series I can boot my test box and build a kernel on it, I'm fairly
> > sure that's far too limited a test to have found all, but its a start.
>
> FWIW, I'm getting a lot of these during light rbd testing. CC'ed
> netdev and linux-mm.
Both are cond_resched() calls, and that's not blocking as such, just a
preemption point, so lets exclude those.
From the school of '_' are free:
---
include/linux/kernel.h | 3 +++
include/linux/sched.h | 6 +++---
kernel/sched/core.c | 12 +++++++++---
3 files changed, 15 insertions(+), 6 deletions(-)
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -162,6 +162,7 @@ extern int _cond_resched(void);
#endif
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
+ void ___might_sleep(const char *file, int line, int preempt_offset);
void __might_sleep(const char *file, int line, int preempt_offset);
/**
* might_sleep - annotation for functions that can sleep
@@ -176,6 +177,8 @@ extern int _cond_resched(void);
# define might_sleep() \
do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
#else
+ static inline void ___might_sleep(const char *file, int line,
+ int preempt_offset) { }
static inline void __might_sleep(const char *file, int line,
int preempt_offset) { }
# define might_sleep() do { might_resched(); } while (0)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2754,7 +2754,7 @@ static inline int signal_pending_state(l
extern int _cond_resched(void);
#define cond_resched() ({ \
- __might_sleep(__FILE__, __LINE__, 0); \
+ ___might_sleep(__FILE__, __LINE__, 0); \
_cond_resched(); \
})
@@ -2767,14 +2767,14 @@ extern int __cond_resched_lock(spinlock_
#endif
#define cond_resched_lock(lock) ({ \
- __might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \
+ ___might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET);\
__cond_resched_lock(lock); \
})
extern int __cond_resched_softirq(void);
#define cond_resched_softirq() ({ \
- __might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET); \
+ ___might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET); \
__cond_resched_softirq(); \
})
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7078,8 +7078,6 @@ static inline int preempt_count_equals(i
void __might_sleep(const char *file, int line, int preempt_offset)
{
- static unsigned long prev_jiffy; /* ratelimiting */
-
/*
* Blocking primitives will set (and therefore destroy) current->state,
* since we will exit with TASK_RUNNING make sure we enter with it,
@@ -7093,6 +7091,14 @@ void __might_sleep(const char *file, int
(void *)current->task_state_change))
__set_current_state(TASK_RUNNING);
+ ___might_sleep(file, line, preempt_offset);
+}
+EXPORT_SYMBOL(__might_sleep);
+
+void ___might_sleep(const char *file, int line, int preempt_offset)
+{
+ static unsigned long prev_jiffy; /* ratelimiting */
+
rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
!is_idle_task(current)) ||
@@ -7122,7 +7128,7 @@ void __might_sleep(const char *file, int
#endif
dump_stack();
}
-EXPORT_SYMBOL(__might_sleep);
+EXPORT_SYMBOL(___might_sleep);
#endif
#ifdef CONFIG_MAGIC_SYSRQ
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