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| author | Peter Zijlstra <peterz@infradead.org> | 2014-09-24 10:18:55 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-10-28 10:56:52 +0100 |
| commit | 8eb23b9f35aae413140d3fda766a98092c21e9b0 (patch) | |
| tree | 657a91ed72882475ada772da052a8a332d70a2dc /kernel/sched | |
| parent | 26cabd31259ba43f68026ce3f62b78094124333f (diff) | |
| download | linux-8eb23b9f35aae413140d3fda766a98092c21e9b0.tar.gz linux-8eb23b9f35aae413140d3fda766a98092c21e9b0.tar.bz2 linux-8eb23b9f35aae413140d3fda766a98092c21e9b0.zip | |
sched: Debug nested sleeps
Validate we call might_sleep() with TASK_RUNNING, which catches places
where we nest blocking primitives, eg. mutex usage in a wait loop.
Since all blocking is arranged through task_struct::state, nesting
this will cause the inner primitive to set TASK_RUNNING and the outer
will thus not block.
Another observed problem is calling a blocking function from
schedule()->sched_submit_work()->blk_schedule_flush_plug() which will
then destroy the task state for the actual __schedule() call that
comes after it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140924082242.591637616@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0456a55fc27f..5b4b96b27cd7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7298,6 +7298,19 @@ 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, + * otherwise we will destroy state. + */ + if (WARN(current->state != TASK_RUNNING, + "do not call blocking ops when !TASK_RUNNING; " + "state=%lx set at [<%p>] %pS\n", + current->state, + (void *)current->task_state_change, + (void *)current->task_state_change)) + __set_current_state(TASK_RUNNING); + rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && !is_idle_task(current)) || |