Messages in this thread | | | Subject | Re: [PATCH v4 0/5] cpumask: Fix invalid uniprocessor assumptions | From | Sander Vanheule <> | Date | Sun, 03 Jul 2022 09:50:51 +0200 |
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On Sat, 2022-07-02 at 13:38 -0700, Andrew Morton wrote: > On Sat, 2 Jul 2022 18:08:23 +0200 Sander Vanheule <sander@svanheule.net> wrote: > > > On uniprocessor builds, it is currently assumed that any cpumask will > > contain the single CPU: cpu0. This assumption is used to provide > > optimised implementations. > > > > The current assumption also appears to be wrong, by ignoring the fact > > that users can provide empty cpumask-s. This can result in bugs as > > explained in [1]. > > It's a little unkind to send people off to some link to explain the > very core issue which this patchset addresses! So I enhanced this > paragraph: > > : The current assumption also appears to be wrong, by ignoring the fact that > : users can provide empty cpumasks. This can result in bugs as explained in > : [1] - for_each_cpu() will run one iteration of the loop even when passed > : an empty cpumask.
Makes sense to add this, sorry for the inconvenience.
Just to make sure, since I'm not familiar with the process for patches going through the mm tree, can I still send a v5 to move the last patch forward in the series, and to include Yury's tags?
Best, Sander
> > This series introduces some basic tests, and updates the optimisations > > for uniprocessor builds. > > > > The x86 patch was written after the kernel test robot [2] ran into a > > failed build. I have tried to list the files potentially affected by the > > changes to cpumask.h, in an attempt to find any other cases that fail on > > !SMP. I've gone through some of the files manually, and ran a few cross > > builds, but nothing else popped up. I (build) checked about half of the > > potientally affected files, but I do not have the resources to do them > > all. I hope we can fix other issues if/when they pop up later. > > > > [1] https://lore.kernel.org/all/20220530082552.46113-1-sander@svanheule.net/ > > [2] https://lore.kernel.org/all/202206060858.wA0FOzRy-lkp@intel.com/ >
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