Re: WARNING: at mm/mremap.c:211 move_page_tables in i386

[Joel Fernandes]

On Sun, Jul 12, 2020 at 08:51:26PM -0700, Linus Torvalds wrote:
> > > Maybe saying "doing the pmd copies for the initial stack isn't
> > > important, so let's just note this as a special case and get rid of
> > > the WARN_ON()" might be an alternative solution.
> >
> > Personally, I feel it is better to keep the warning just so in the future we
> > can detect any bugs.
> 
> I don't disagree, the warning didn't happen to find a bug now, but it
> did fine a case we might be able to do better.
> 
> So now that I feel we understand the issue, and it's not a horrible
> problem, just a (very hard to trigger) warning, I don't think there's
> any huge hurry.
> 
> I think think I will - for now - change the WARN_ON() to
> WARN_ON_ONCE() (so that it doesn't floow the logs if somebody triggers
> this odd special case  this malisiously), and add a note about how
> this happens to the code for posterito.
> 
> And if/when you figure out a better way to fix it, we can update the note.
> 
> Ok?

Yes, that sounds great to me.

thanks,

 - Joel