About pmap_mapdev() & pmap_unmapdev()

Konstantin Belousov
Sat, 04 Oct 2014 09:20:30 -0000

On Sat, Oct 04, 2014 at 05:53:26PM +0900, Kohji Okuno
wrote:
> Hi, Konstantin,
>
> > At the end of the mail is commit candidate.  I did not even compiled
this.
> > Can you test and report back, please ?
>
> Could you check the following?
> (1) should use kernel_pmap->pm_stats.resident_count
>                           ^^^
>     I'm sorry. My patch was wrong.
As well as mine.

>
> (2) should use pmap_resident_count_inc() in amd64.
Correct.

>
>
> I will test, later.
>
> In addtion, I have one question.
> In current and 10-stable, is vm_map_delete() called by kva_free()?
No, kva_free() only releases the vmem backing, leaving the page
tables intact.  This is why I only did the stable/9 patch.

> If vm_map_delete() is called, this fix is needed in current and
> 10-stable, I think.

Updated patch below.

Index: amd64/amd64/pmap.c
==================================================================---
amd64/amd64/pmap.c	(revision 272506)
+++ amd64/amd64/pmap.c	(working copy)
@@ -5040,6 +5040,9 @@ pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, in
 	pa = trunc_page(pa);
 	for (tmpsize = 0; tmpsize < size; tmpsize += PAGE_SIZE)
 		pmap_kenter_attr(va + tmpsize, pa + tmpsize, mode);
+	PMAP_LOCK(kernel_pmap);
+	pmap_resident_count_inc(kernel_pmap, OFF_TO_IDX(size));
+	PMAP_UNLOCK(kernel_pmap);
 	pmap_invalidate_range(kernel_pmap, va, va + tmpsize);
 	pmap_invalidate_cache_range(va, va + tmpsize);
 	return ((void *)(va + offset));
Index: i386/i386/pmap.c
==================================================================---
i386/i386/pmap.c	(revision 272506)
+++ i386/i386/pmap.c	(working copy)
@@ -5066,10 +5066,14 @@ pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, in
 	size = roundup(offset + size, PAGE_SIZE);
 	pa = pa & PG_FRAME;

-	if (pa < KERNLOAD && pa + size <= KERNLOAD)
+	if (pa < KERNLOAD && pa + size <= KERNLOAD) {
 		va = KERNBASE + pa;
-	else
+	} else {
 		va = kmem_alloc_nofault(kernel_map, size);
+		PMAP_LOCK(kernel_pmap);
+		kernel_pmap->pm_stats.resident_count += OFF_TO_IDX(size);
+		PMAP_UNLOCK(kernel_pmap);
+	}
 	if (!va)
 		panic("pmap_mapdev: Couldn't alloc kernel virtual memory");