pmap_qenter() - the page *must* be wired - is violated

Kostik Belousov kostikbel at gmail.com
Thu Oct 6 11:52:57 UTC 2011


On Thu, Oct 06, 2011 at 01:45:16PM +0200, Svatopluk Kraus wrote:
> On Wed, Oct 5, 2011 at 4:53 PM, Kostik Belousov <kostikbel at gmail.com> wrote:
> > On Wed, Oct 05, 2011 at 02:28:01PM +0200, Svatopluk Kraus wrote:
> >> Hi,
> >>
> >>   I found out that on a few places pmap_qenter() is called on pages
> >> which are not wired. For example, in the following functions, when
> >> vm_pager_get_pages() is called, the pages are not wired:
> >>
> >>   exec_map_first_page() in sys/kern/kern_exec.c
> >>   vm_fault_hold() in sys/vm/vm_fault.c
> >>   vm_imgact_hold_page() in sys/vm/vm_glue.c
> >>   vm_object_populate() in sys/vm/vm_object.c
> >>   mdstart_swap() in sys/dev/md/md.c
> >>
> >>   Is the rule violated or the rule should be changed?
> >
> > Lets first discuss where did you found the calls to pmap_qenter().
> > Can you point out exact line numbers of the calls to pmap_qenter()
> > that you consider problematic ?
> >
> > In fact, the requirement probably shall be 'no swapout allowed'. E.g.,
> > the busy page is fully qualified to be used together with pmap_qenter().
> 
> Well, I just follow description above pmap_qenter() blindly and test for
> page wire_count inside the function. All function calls, I mentioned before,
> are OK as pages are VPO_BUSY'd. Thanks for your explanation.
Still, I am not aware of any (direct) calls to pmap_qenter in the mentioned
functions.
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