Re: 2.6.23-rc7-mm1: r/o mounts joke with lockdep

From: Dave Hansen
Date: Mon Sep 24 2007 - 12:46:30 EST


On Mon, 2007-09-24 at 09:26 -0700, Andrew Morton wrote:
> On Mon, 24 Sep 2007 13:51:05 +0400 Alexey Dobriyan <adobriyan@xxxxx> wrote:
>
> > static void lock_and_coalesce_cpu_mnt_writer_counts(void)
> > {
> > int cpu;
> > struct mnt_writer *cpu_writer;
> >
> > for_each_possible_cpu(cpu) {
> > cpu_writer = &per_cpu(mnt_writers, cpu);
> > spin_lock_nested(&cpu_writer->lock, 42);
> > ^^^^
> >
> > What the heck is going on?
>
> that was some random 2:00AM hack by me to make the warnings go away.
>
> > Given that MAX_LOCKDEP_SUBCLASSES is only 8,
> > this reliably turns off lockdep at boot.
>
> that explains why it worked so well.

Arjan gave me some ideas on how to fix this more properly. I'm trying
to reproduce it and working on a patch now.

-- Dave

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