netdev - Re: Kernel 4.6.7-rt14 kernel workqueue lockup - rtnl deadlock plus syscall endless loop

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Message-Id: <20170117.140552.539738967862859087.davem@davemloft.net>
Date:   Tue, 17 Jan 2017 14:05:52 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     EladN@...at.com
Cc:     netdev@...r.kernel.org
Subject: Re: Kernel 4.6.7-rt14 kernel workqueue lockup - rtnl deadlock plus
 syscall endless loop

From: Elad Nachman <EladN@...at.com>
Date: Tue, 17 Jan 2017 18:15:19 +0000

> Any thought about limiting the amount of busy polling?  Say if more
> than X polls are done within a jiffy, then at least for preemptable
> kernels you can sleep for a jiffy inside the syscall to yield the
> CPU for a while?

We cannot yield there, because we must return immediately from this
context in order to drop the sysctl locks and references.