linux-kernel - Re: [PATCH 4/4] lockdep: make MAX_LOCK

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Message-ID: <alpine.LNX.2.20.1709281646360.24635@cae-iprp-alln-lb.cisco.com>
Date:   Thu, 28 Sep 2017 16:51:46 -0700
From:   Govindarajulu Varadarajan <gvaradar@...co.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     <benve@...co.com>, <bhelgaas@...gle.com>,
        <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <jlbec@...lplan.org>, <hch@....de>, <mingo@...hat.com>
Subject: Re: [PATCH 4/4] lockdep: make MAX_LOCK_DEPTH configurable from
 Kconfig

On Thu, 28 Sep 2017, Peter Zijlstra wrote:

> On Wed, Sep 27, 2017 at 02:42:20PM -0700, Govindarajulu Varadarajan wrote:
>> Make MAX_LOCK_DEPTH configurable. It is set to 48 right now. Number of
>> VFs under a PCI pf bus can exceed 48 and this disables lockdep.
>>
>> lockdep currently allows max of 63 held_locks.
>
> But why a config knob? Why not just raise the number to 64
> unconditionally? And is that sufficient; you only state 48 is
> insufficient, you don't actually state the VF limit.
>

I did not want to change the default configuration for everyone.

I will change it 63 unconditionally in v2 and resubmit the series.