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| author | Stephen Boyd <sboyd@codeaurora.org> | 2012-03-29 02:10:47 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-03-29 08:34:45 +0200 |
| commit | 6135fc1eb4b1c9ae5f535507ed59591bab51e630 (patch) | |
| tree | d77513f138b94550b27394c907e9caf9f3d990a9 /kernel | |
| parent | cpusets: Remove an unused variable (diff) | |
| download | linux-6135fc1eb4b1c9ae5f535507ed59591bab51e630.tar.xz linux-6135fc1eb4b1c9ae5f535507ed59591bab51e630.zip | |
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')
| -rw-r--r-- | kernel/sched/core.c | 8 |
1 files changed, 1 insertions, 7 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9c1629c90b2d..929fd857ef88 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(); } /* |