linux-kernel - Re: Softlockup and Hardlockup sample test module

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Message-ID: <90446.1523819531@turing-police.cc.vt.edu>
Date:   Sun, 15 Apr 2018 15:12:11 -0400
From:   valdis.kletnieks@...edu
To:     Ivid Suvarna <ivid.suvarna@...il.com>
Cc:     Kernel development list <linux-kernel@...r.kernel.org>,
        kernelnewbies@...nelnewbies.org
Subject: Re: Softlockup and Hardlockup sample test module

On Sun, 15 Apr 2018 13:17:27 +0530, Ivid Suvarna said:

> I had tried with the module where I put a busy loop inside spinlock
> but was not able to cause any lockups. Maybe this is because of SMP
> which schedule the job to other CPU. "How do I make a task to run on
> single CPU only?"

So you get a kernel thread that's taken a lock and will busy-loop and not free
it.  What sort of lockup do you expect will be detected from this? Would the
results be any different if you didn't take a lock before busy-looping?

For bonus points - what additional things have to happen before a livelock
happens?

And before a deadlock happens?

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