From: Michael Ellerman <mpe@ellerman•id.au>
To: Ian Munsie <imunsie@au1•ibm.com>
Cc: Frederic Barrat <frederic.barrat@fr•ibm.com>,
linuxppc-dev <linuxppc-dev@lists•ozlabs.org>
Subject: Re: [PATCH] cxl: Fix reference count on struct pid when attaching
Date: Tue, 03 Nov 2015 12:00:46 +1100 [thread overview]
Message-ID: <1446512446.31246.5.camel@ellerman.id.au> (raw)
In-Reply-To: <1446507545-sup-9915@delenn.ozlabs.ibm.com>
On Tue, 2015-11-03 at 10:48 +1100, Ian Munsie wrote:
> Excerpts from Michael Ellerman's message of 2015-11-02 11:53:45 +1100:
> > On Thu, 2015-10-29 at 13:39 +0100, Frederic Barrat wrote:
> >
> > > When the cxl driver creates a context, it stores the pid of the
> > > calling task, incrementing the reference count on the struct
> > > pid. Current code mistakenly increments the reference count twice,
> > > once through get_task_pid(), once through get_pid(). The reference
> > > count is only decremented once on detach, thus the struct pid of the
> > > task attaching is never freed. The fix is to simply remove the call to
> > > get_pid().
> > >
> > > Signed-off-by: Frederic Barrat <frederic.barrat@fr•ibm.com>
> >
> > What's the symptom?
>
> Everytime a process attached to a capi device it would reduce the total
> number of processes that can be running simultaneously by one.
Right, and reduced it permanently until the next reboot, so eventually you'd
kill your system presumably.
cheers
next prev parent reply other threads:[~2015-11-03 1:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-29 12:39 [PATCH] cxl: Fix reference count on struct pid when attaching Frederic Barrat
2015-10-30 0:31 ` Andrew Donnellan
2015-10-30 2:56 ` Ian Munsie
2015-11-02 0:53 ` Michael Ellerman
2015-11-02 23:48 ` Ian Munsie
2015-11-03 1:00 ` Michael Ellerman [this message]
2015-11-03 8:17 ` Frederic Barrat
2015-11-03 9:11 ` Michael Ellerman
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