(no subject)

On Wednesday, May 23, 2012 9:42:14 am Ian FREISLICH wrote:
> John Baldwin wrote:
> > On Wednesday, May 23, 2012 12:28:53 am Ian FREISLICH wrote:
> > > (kgdb) frame 7
> > > #7  0xc0878682 in pmap_enter (pmap=0xc09e4060, va=3359633408, access=7 
'\a'
> , 
> > >     m=0xc191bf70, prot=7 '\a', wired=1) at 
> > /usr/src/sys/i386/i386/pmap.c:1596
> > > 1596                    root = vm_page_splay(mpte->pindex, root);
> > > (kgdb) l
> > > 1591            root = pmap->pm_root;
> > > 1592            if (root == NULL) {
> > > 1593                    mpte->left = NULL;
> > > 1594                    mpte->right = NULL;
> > > 1595            } else {
> > > 1596                    root = vm_page_splay(mpte->pindex, root);
> > > 1597                    if (mpte->pindex < root->pindex) {
> > > 1598                            mpte->left = root->left;
> > > 1599                            mpte->right = root;
> > > 1600                            root->left = NULL;
> > 
> > Ok, can you do 'p root', 'p mpte', and 'p *mpte'?
> 
> (kgdb) frame 7
> #7  0xc0878682 in pmap_enter (pmap=0xc09e4060, va=3359633408, access=7 '\a', 
>     m=0xc191bf70, prot=7 '\a', wired=1) at 
/usr/src/sys/i386/i386/pmap.c:1596
> 1596                    root = vm_page_splay(mpte->pindex, root);
> (kgdb) p root
> No symbol "root" in current context.
> (kgdb) p mpte
> $1 = 0x0
> (kgdb) p *mpte
> Cannot access memory at address 0x0

Well, mpte being NULL is the cause of your fault. :(  It also seems that the
system is trying to promote a superpage, but it can't find the page table
page that currently maps the individual pages that make up the superpage 
(which is odd).

-- 
John Baldwin