Re: BUG: MAX_LOCKDEP_CHAINS too low!

[Peter Zijlstra]

On Fri, Sep 28, 2018 at 08:06:26AM +0200, Dmitry Vyukov wrote:
> On Fri, Sep 28, 2018 at 7:51 AM, syzbot
> <syzbot+aaa6fa4949cc5d9b7b25@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    c307aaf3eb47 Merge tag 'iommu-fixes-v4.19-rc5' of git://gi..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=13810df1400000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=dfb440e26f0a6f6f
> > dashboard link: https://syzkaller.appspot.com/bug?extid=aaa6fa4949cc5d9b7b25
> > compiler:       gcc (GCC) 8.0.1 20180413 (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+aaa6fa4949cc5d9b7b25@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> +LOCKDEP maintainers,
> 
> What does this BUG mean? And how should it be fixed?
> 
> Thanks
> 
> > BUG: MAX_LOCKDEP_CHAINS too low!

Is the his result of endlessly loading and unloading modules?

In which case, the fix is: don't do that then.