Date: Wed, 23 May 2012 09:50:36 -0400 From: John Baldwin <jhb@freebsd.org> To: Ian FREISLICH <ianf@clue.co.za> Cc: freebsd-current@freebsd.org Subject: Re: Message-ID: <201205230950.36450.jhb@freebsd.org> In-Reply-To: <E1SXBpO-0001ep-Ei@clue.co.za> References: <201205230930.03282.jhb@freebsd.org> <E1SX3Bt-0000qb-JF@clue.co.za> <E1SXBpO-0001ep-Ei@clue.co.za>
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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
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