From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Udo van den Heuvel <udovdh@xs4all.nl>
Cc: RT <linux-rt-users@vger.kernel.org>
Subject: Re: 5.4.13-rt7 stall on CPU?
Date: Tue, 7 Jul 2020 19:47:46 +0200 [thread overview]
Message-ID: <20200707174746.qe5f6w5qju3vo3yr@linutronix.de> (raw)
In-Reply-To: <875822d3-6fcd-1ab0-4ede-ee5134e6211b@xs4all.nl>
On 2020-07-04 05:43:32 [+0200], Udo van den Heuvel wrote:
> > I *think* this happened within the loop in __fget_files(). This function
> > is inlined by __fget_light() and the loop has a RCU-section so it would
> > make sense.
> > Do you run something at an elevated priority in the system?
>
> ntpd (ntpsec) elevates itself.
To the highest possible. Wonderful.
> > I don't know
> > what the other part was doing but somehow one of the file descriptors
> > (network sockets probably) was about to be closed while the other side
> > tried to poll() on it.
>
> Thanks for explaining.
I'm puzzled. On dup() and otherwise on replacement / closing the file
pointer is replaced (with an incremented reference count or NULL ) and
then the reference count of the old file pointer is decremented. So the
zero count could be observed once and then the new pointer should be
seen. So it should not loop for seconds. And then, dup2() is only used
at startup.
> Kind regards,
> Udo
Sebastian
next prev parent reply other threads:[~2020-07-07 17:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-27 13:30 5.4.13-rt7 stall on CPU? Udo van den Heuvel
2020-07-03 19:49 ` Sebastian Andrzej Siewior
2020-07-04 3:43 ` Udo van den Heuvel
2020-07-07 17:47 ` Sebastian Andrzej Siewior [this message]
2020-07-20 9:21 ` Udo van den Heuvel
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