Ingo,
Every so often we get bit by a bug "scheduling in atomic", and it comes
from a rtmutex spin_lock. The bug only happens when that lock has
contention, so we miss it a lot.
This patch adds a might_sleep() to the rt_spin_lock_fastlock to find
bugs where we can schedule in atomic.
The one place that exists now is from do_page_fault and sending a
signal. I wrote a simple crash program that segfaults (attached) and
with this patch, I get the warning.
-- Steve
Signed-off-by: Steven Rostedt <[email protected]>
Index: linux-2.6.21-rt9/kernel/rtmutex.c
===================================================================
--- linux-2.6.21-rt9.orig/kernel/rtmutex.c
+++ linux-2.6.21-rt9/kernel/rtmutex.c
@@ -602,6 +602,8 @@ static inline void
rt_spin_lock_fastlock(struct rt_mutex *lock,
void fastcall (*slowfn)(struct rt_mutex *lock))
{
+ might_sleep();
+
if (likely(rt_mutex_cmpxchg(lock, NULL, current)))
rt_mutex_deadlock_account_lock(lock, current);
else
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main (int argc, char **argv)
{
unsigned long *p = (void*)-1;
printf("crashing...\n");
/* nighty night */
*p = 0xbed;
printf("did we crash??\n");
return 0;
}
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