watchdog pet in kernel module

[Vipul Jain]

On Wed, Dec 4, 2013 at 4:57 PM, <Valdis.Kletnieks at vt.edu> wrote:

> On Wed, 04 Dec 2013 16:45:44 -0800, Vipul Jain said:
>
> > If you don't mind can you please provide me more insight as what can be
> > false alarm I can encounter to move pet inside kernel module?
>
> The issue isn't false alarms - it's failure to alarm when it should.
>
> The problem is that it's possible for a kernel to get wedged in such a way
> that
> a kernel thread is still able to feed the watchdog timer on a regular
> basis,
> but userspace is effectively hung and unable to proceed.  For example, if
> an
> OOPS happens while a filesystem lock is held, all future userspace
> references
> to that filesystem (and possibly all filesystems of the same type) will
> hang,
> eventually strangling the box while the kernel is still perfectly able to
> keep
> the watchdog working.
>
> Hi Valdis,

I see what you are saying but what if the user process that's feeding the
dog gets hung and rest of the system is fine then it will bring the whole
system down won't it? I basically want to avoid this?

Regards,
Vipul.
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