Re: linux-next boot error: WARNING: workqueue cpumask: online intersect > possible intersect

[Dmitry Vyukov]

On Fri, Jun 7, 2019 at 10:33 AM syzbot
<syzbot+4d497898effeb1936245@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    ae3cad8f Add linux-next specific files for 20190603
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=164f802ea00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=7ccec0766d83706f
> dashboard link: https://syzkaller.appspot.com/bug?extid=4d497898effeb1936245
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+4d497898effeb1936245@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> smpboot: CPU0: Intel(R) Xeon(R) CPU @ 2.30GHz (family: 0x6, model: 0x3f,
> stepping: 0x0)
> Performance Events: unsupported p6 CPU model 63 no PMU driver, software
> events only.
> rcu: Hierarchical SRCU implementation.
> NMI watchdog: Perf NMI watchdog permanently disabled
> smp: Bringing up secondary CPUs ...
> x86: Booting SMP configuration:
> .... node  #0, CPUs:      #1
> MDS CPU bug present and SMT on, data leak possible. See
> https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for
> more details.
> smp: Brought up 2 nodes, 2 CPUs
> smpboot: Max logical packages: 1
> smpboot: Total of 2 processors activated (9200.00 BogoMIPS)
> devtmpfs: initialized
> clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns:
> 19112604462750000 ns
> futex hash table entries: 512 (order: 4, 65536 bytes)
> xor: automatically using best checksumming function   avx
> PM: RTC time: 07:02:18, date: 2019-06-03
> NET: Registered protocol family 16
> audit: initializing netlink subsys (disabled)
> cpuidle: using governor menu
> ACPI: bus type PCI registered
> dca service started, version 1.12.1
> PCI: Using configuration type 1 for base access
> WARNING: workqueue cpumask: online intersect > possible intersect

+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?


> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxxx
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000f19676058ab7adc4%40google.com.
> For more options, visit https://groups.google.com/d/optout.