From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [Ksummit-discuss] [MAINTAINERS SUMMIT] & [TECH TOPIC] Improve regression tracking Date: Wed, 05 Jul 2017 08:32:28 -0700 Message-ID: <1499268748.3668.20.camel@HansenPartnership.com> References: <576cea07-770a-4864-c3f5-0832ff211e94@leemhuis.info> <20170703123025.7479702e@gandalf.local.home> <20170705084528.67499f8c@gandalf.local.home> <4080ecc7-1aa8-2940-f230-1b79d656cdb4@redhat.com> <20170705092757.63dc2328@gandalf.local.home> <20170705140607.GA30187@kroah.com> <20170705143341.oees22k2snhtmkxo@sirena.org.uk> <20170705103658.226099c6@gandalf.local.home> <1499266228.3668.10.camel@HansenPartnership.com> <20170705105651.5da9c969@gandalf.local.home> <1499267389.3668.16.camel@HansenPartnership.com> <20170705112047.23ee09f6@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20170705112047.23ee09f6-f9ZlEuEWxVcJvu8Pb33WZ0EMvNT87kid@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Steven Rostedt Cc: Carlos O'Donell , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Shuah Khan , ksummit-discuss-cunTk1MwBs98uUxBSJOaYoYkZiVZrdSR2LY78lusg7I@public.gmane.org, Thorsten Leemhuis List-Id: linux-api@vger.kernel.org On Wed, 2017-07-05 at 11:20 -0400, Steven Rostedt wrote: > On Wed, 05 Jul 2017 08:09:49 -0700 > James Bottomley wrote: > >   > > > > > > > > > > > > > you're protecting was accessed outside the lock, which is the > > > > usual source of concurrency problems.  In other words lockdep > > > > is useful but it's not a panacea.   > > > > > > Still not an excuse to not have lockdep enabled during tests.   > > > > OK, what makes you think lockdep isn't enabled?  Since Kconfig is > > so complex, I usually use a distro config ... they have it enabled > > (or at least openSUSE does), so it's enabled for everything I do. > > openSuSE has it enabled? I hope not for its production config, as > lockdep has a huge performance penalty. Then, surely, it's the last thing we want when tracking down race conditgions since it will alter timings dramatically. > I'm thinking you don't have it enabled. What config are you looking > at? The actual config that does the testing of locks is > CONFIG_PROVE_LOCKING, which selects LOCKDEP to be compiled in. This is what it has: jejb@jarvis:~/git/linux-build> grep LOCKDEP /boot/config-4.4.73-18.17-default  CONFIG_LOCKDEP_SUPPORT=y James