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authorStephen Boyd <sboyd@codeaurora.org>2012-03-28 17:10:47 -0700
committerIngo Molnar <mingo@kernel.org>2012-03-29 08:34:45 +0200
commit6135fc1eb4b1c9ae5f535507ed59591bab51e630 (patch)
treed77513f138b94550b27394c907e9caf9f3d990a9 /kernel/sched
parent160594e99dbbb0a5600ad922c630952c7c1c14bf (diff)
sched: Fix __schedule_bug() output when called from an interrupt
If schedule is called from an interrupt handler __schedule_bug() will call show_regs() with the registers saved during the interrupt handling done in do_IRQ(). This means we'll see the registers and the backtrace for the process that was interrupted and not the full backtrace explaining who called schedule(). This is due to 838225b ("sched: use show_regs() to improve __schedule_bug() output", 2007-10-24) which improperly assumed that get_irq_regs() would return the registers for the current stack because it is being called from within an interrupt handler. Simply remove the show_reg() code so that we dump a backtrace for the interrupt handler that called schedule(). [ I ran across this when I was presented with a scheduling while atomic log with a stacktrace pointing at spin_unlock_irqrestore(). It made no sense and I had to guess what interrupt handler could be called and poke around for someone calling schedule() in an interrupt handler. A simple test of putting an msleep() in an interrupt handler works better with this patch because you can actually see the msleep() call in the backtrace. ] Also-reported-by: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Satyam Sharma <satyam@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1332979847-27102-1-git-send-email-sboyd@codeaurora.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c8
1 files changed, 1 insertions, 7 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9c1629c90b2..929fd857ef8 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3099,8 +3099,6 @@ EXPORT_SYMBOL(sub_preempt_count);
*/
static noinline void __schedule_bug(struct task_struct *prev)
{
- struct pt_regs *regs = get_irq_regs();
-
if (oops_in_progress)
return;
@@ -3111,11 +3109,7 @@ static noinline void __schedule_bug(struct task_struct *prev)
print_modules();
if (irqs_disabled())
print_irqtrace_events(prev);
-
- if (regs)
- show_regs(regs);
- else
- dump_stack();
+ dump_stack();
}
/*