Messages in this thread | | | Date | Wed, 24 Jul 2019 10:41:29 -0700 | From | Eric Biggers <> | Subject | Re: linux-next boot error: WARNING: workqueue cpumask: online intersect > possible intersect |
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On Tue, Jul 23, 2019 at 09:31:27AM -0700, Eric Biggers wrote: > On Tue, Jul 23, 2019 at 10:16:24AM +0200, 'Dmitry Vyukov' via syzkaller-bugs wrote: > > On Tue, Jun 11, 2019 at 8:52 PM Tejun Heo <tj@kernel.org> wrote: > > > > > > Hello, > > > > > > On Fri, Jun 07, 2019 at 10:45:45AM +0200, Dmitry Vyukov wrote: > > > > +workqueue maintainers and Michael who added this WARNING > > > > > > > > The WARNING was added in 2017, so I guess it's a change somewhere else > > > > that triggered it. > > > > The WARNING message does not seem to give enough info about the caller > > > > (should it be changed to WARN_ONCE to print a stack?). How can be root > > > > cause this and unbreak linux-next? > > > > > > So, during boot, workqueue builds masks of possible cpus of each node > > > and stores them on wq_numa_possible_cpumask[] array. The warning is > > > saying that somehow online cpumask of a node became a superset of the > > > possible mask, which should never happen. > > > > > > Dumping all masks in wq_numa_possible_cpumasks[] and cpumask_of_node() > > > of each node should show what's going on. > > > > This has reached upstream and all subsystem subtrees, now all Linux > > trees are boot broken (except for few that still lack behind): > > https://syzkaller.appspot.com/upstream > > > > No new Linux code is tested by syzbot at this point. > > > > AFAICS, what's actually happening is that the boot fails due to a different bug, > "general protection fault in dma_direct_max_mapping_size" -- which is a real > boot error, not just a warning; see > https://lkml.kernel.org/lkml/20190723161425.GA23641@gmail.com/ > > syzbot then sees "WARNING: workqueue cpumask: online intersect > possible > intersect" in the console output prior to that, and uses that as the bug title. > > It's not obvious that syzbot would report "WARNING: workqueue cpumask: online > intersect > possible intersect" without the real boot error too. > > Nevertheless the issue is still there and something needs to be done about it. >
The real boot error "general protection fault in dma_direct_max_mapping_size" is fixed in mainline now. I believe that unblocks syzbot testing, since it doesn't appear to have been blocked by "WARNING: workqueue cpumask: online intersect > possible intersect" by itself.
Anyway: Tejun and Michael, any other ideas for why "WARNING: workqueue cpumask: online intersect > possible intersect" is still happening?
- Eric
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