Re: scheduling while atomic & hang.

From: Ingo Molnar
Date: Fri Jul 05 2013 - 02:51:21 EST



* H. Peter Anvin <hpa@xxxxxxxxx> wrote:

> On 07/03/2013 07:49 PM, Linus Torvalds wrote:
> >> [<ffffffff816f42bf>] __schedule+0x94f/0x9c0
> >> [<ffffffff816f487e>] schedule_user+0x2e/0x70
> >> [<ffffffff816f6de4>] retint_careful+0x12/0x2e
>
> This call trace does indeed indicate that we took a hardware
> interrupt which caused a reschedule. It doesn't necessarily have to
> be a quantum expiration interrupt, it could just as easily be an I/O
> completion interrupt.

Too bad the kernel stack frame at this point is so small [we are just
before return to userspace], so we don't really get our usual trace of
recent activities via the '?' entries ...

It would be nice to have a full-kernel-stack backtrace printout as an
option, which prints entries 'above' the current RSP.

I've Cc:-ed Frederic, maybe he has interest in implementing that?

Thanks,

Ingo
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