Messages in this thread | | | Date | Thu, 2 Feb 2023 20:29:04 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [RFC][PATCH 1/4] locktorture: Add nested_[un]lock() hooks and nlocks parameter |
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On Thu, Feb 02, 2023 at 07:56:05PM -0800, John Stultz wrote: > On Thu, Feb 2, 2023 at 6:05 PM Paul E. McKenney <paulmck@kernel.org> wrote: > > > > On Thu, Feb 02, 2023 at 10:34:06PM +0000, John Stultz wrote: > > > In order ot extend locktorture to support lock nesting, add > > > nested_lock() and nested_unlock() hooks to the torture ops. > > > > > > These take a 32bit lockset mask which is generated at random, > > > so some number of locks will be taken before the main lock is > > > taken and released afterwards. > > > > > > Additionally, add nlocks module parameter to allow specifying > > > the number of nested locks to be used. > > > > > > This has been helpful to uncover issues in the proxy-exec > > > series development. > > > > > > This was inspired by locktorture extensions originally implemented > > > by Connor O'Brien, for stress testing the proxy-execution series: > > > https://lore.kernel.org/lkml/20221003214501.2050087-12-connoro@google.com/ > > > > > > Comments or feedback would be greatly appreciated! > > > > I have pulled this in for testing and further review, thank you! > > > > Should either of these files have a locktorture.nlocks=<whatever> > > added? > > > > tools/testing/selftests/rcutorture/configs/lock/LOCK02.boot > > tools/testing/selftests/rcutorture/configs/lock/LOCK05.boot > > > > The first is for mutex_lock and the second for rtmutex_lock. > > Potentially? I wasn't aware of these files. Is there some > documentation on the intent behind them?
There is a LOCK02 file that contains Kconfig options and the LOCK02.boot file contains kernel boot parameters. There is a CFLIST file that contains the list of such files that the command below will test by default.
The best documentation is probably here:
https://paulmck.livejournal.com/57769.html https://paulmck.livejournal.com/58077.html
> While the nested locking is useful to cause different lock chains to > test boosting or proxy-execution, I worry they may cause extra noise > that could distract from just thrashing the *mutex lock primitive if > that's the existing intent.
The intent is to find bugs by whatever means necessary, within reason.
> So we might want additional config files for the nested case.
That would work.
> > This did pass a quick "torture.sh --do-none --do-locktorture", which is > > good, but this uses the existing .boot files. > > Yeah, probably no effective change in that case.
At least nothing else got broken. ;-)
Thanx, Paul
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