traversing vma on nommu

[Liam R. Howlett]

* Liam R. Howlett <Liam.Howlett at oracle.com> [241106 21:53]:
> * Hajime Tazaki <thehajime at gmail.com> [241106 16:47]:
> > 
> > Hello,
> > 
> > Thanks for the detail information.
> > 
> > > Can you add some (totally untested) debug to the exit path in
> > > kernel/acct.c?
> > > 
> > > +#include <linux/maple_tree.h>
> > > 
> > > ...
> > > 		mmap_read_lock(mm);                                                                                     
> 
> I probably should have suggested adding:
> 
> if (!strcmp(current->comm, "apk")) {
> > > +		mt_dump(&mm->mm_mt, mt_dump_hex);
> > > +		mt_validate(&mm->mm_mt);
>  }
> 
> > >                 for_each_vma(vmi, vma)
> > >                         vsize += vma->vm_end - vma->vm_start;                                                           
> > >                 mmap_read_unlock(mm);                                                                                   
> > > 
> > > You will need to enable CONFIG_DEBUG_MAPLE_TREE on the kernel.
> > 
> > I quickly added the code and here is the just part of the output.
> > It's being so long; I put the full output at below.
> > 
> > https://gist.github.com/thehajime/30485f105ab78a09b66691eb024dc011
> > 
> > # I'm not yet looking at carefully the log but will do.
> 
> I think it's probably more important to try a real build.  I'm surprised
> it gets as far as it does with the sequential nulls.
> 
> We have 32b testing in userspace for the maple tree, and it works.
> maple_tree: 139594121 of 139594121 tests passed
> 
> So at least that much is known to work.
> 
> As you are probably finding out, building a nommu test system is a pain
> (or you probably already know and want to stop doing it and use UML..).
> 
> I'll give my m68k build a go against v6.12-rc6.

I was able to build 6.12.0-rc6 for m68k nommu (m5208).  It boots and
tests the maple tree fine:

TEST STARTING

maple_tree: 3808238 of 3808238 tests passed

# uname -a
uClinux buildroot 6.12.0-rc6 #2 Wed Nov  6 22:14:42 EST 2024 m68k GNU/Linux


> 
> I had a look at your patches and nothing seems to pop out against
> any vma specific code changes in there?

Thanks,
Liam