On 3/29/2012 3:16 AM, tip-bot for Stephen Boyd wrote: > Commit-ID: 6135fc1eb4b1c9ae5f535507ed59591bab51e630 > Gitweb: http://git.kernel.org/tip/6135fc1eb4b1c9ae5f535507ed59591bab51e630 > Author: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> > AuthorDate: Wed, 28 Mar 2012 17:10:47 -0700 > Committer: Ingo Molnar <mingo@xxxxxxxxxx> > CommitDate: Thu, 29 Mar 2012 08:34:45 +0200 > > 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@xxxxxxxxxx> > Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> > Cc: Satyam Sharma <satyam@xxxxxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Link: http://lkml.kernel.org/r/1332979847-27102-1-git-send-email-sboyd@xxxxxxxxxxxxxx > Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Acked-by: Chris Metcalf <cmetcalf@xxxxxxxxxx> We have been using this same exact patch internally for a while now, and by a curious fluke of timing, I sent email to Ingo and to Satyam Sharma pointing out that we really should re-look at the original change just yesterday :-) -- Chris Metcalf, Tilera Corp. http://www.tilera.com -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html