Re: 2.6.29 git master and PAT problems

[Pallipadi, Venkatesh]

On Mon, Mar 30, 2009 at 05:28:15PM -0700, Pallipadi, Venkatesh wrote:
> On Mon, Mar 30, 2009 at 03:31:09PM -0700, Arkadiusz Miskiewicz wrote:
> > On Monday 30 of March 2009, Pallipadi, Venkatesh wrote:
> > 
> > More info follows. Now I've switched to
> > e1c502482853f84606928f5a2f2eb6da1993cda1 which contains latest drm fixes and
> > now I get much lower numbers of PAT errors but still.
> > 
> > > On Mon, 2009-03-30 at 14:31 -0700, Arkadiusz Miskiewicz wrote:
> > > > On Monday 30 of March 2009, Pallipadi, Venkatesh wrote:
> > > > > Patch here should get rid of these errors.
> > > > >
> > > > > http://marc.info/?l=linux-kernel&m=123788806506230&w=2
> > > > >
> > > > > The patch is in tip and on its way to upstream.
> > > >
> > > > The problem is that kernel I'm running already contains this patch (it's
> > > > merged already). Other ideas?
> > > >
> > > > ratelimiting that error is good IMO anyway.
> > >
> > > Rate limiting will just work around the problem here. Ideally we should
> > > never see these errors. So, it will be better if we can narrow down on
> > > the bug resulting in these error messages.
> > 
> > Of course it's better. I'm saying that when these messages "fire" then it's
> > hard to do anything else on the system for a while until these stop.
> > 
> > > Can you please send me the output of
> > > # cat /debug/x86/pat_memtype_list
> > > with debugfs mounted.
> > > and
> > > # cat /proc/mtrr
> > 
> 
> There seems to be two different problems here.
> - We should not have that many single page ranges reserved. That will cause a
> performance problem with drm even without the "freeing invalid type" error.
> - "freeing invalid type" error itself. Seems to be caused due to some
> unbalanced free along the drm path. We tried to find anything obvious in the
> code that may be causing problem here. But, haven't found anything so far.
> Will try to reproduce the problem internally and debug it further.
> 

OK. I think we have root caused the thinko that was resulting in
"freeing invalid type" error. Can you try the below test
patch. Patch is not final version and may need some cleanup.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 640339e..c161700 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -847,7 +847,8 @@ cleanup_ret:
  * can be for the entire vma (in which case size can be zero).
  */
 void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
-			unsigned long size)
+			unsigned long size,
+			unsigned long vstart, unsigned long vend)
 {
 	unsigned long i;
 	resource_size_t paddr;
@@ -866,7 +867,7 @@ void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
 		return;
 	}
 
-	if (size != 0 && size != vma_size) {
+	if (size != 0) {
 		/* free page by page, using pfn and size */
 		paddr = (resource_size_t)pfn << PAGE_SHIFT;
 		for (i = 0; i < size; i += PAGE_SIZE) {
@@ -874,9 +875,12 @@ void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
 			free_pfn_range(paddr, PAGE_SIZE);
 		}
 	} else {
-		/* free entire vma, page by page, using the pfn from pte */
-		for (i = 0; i < vma_size; i += PAGE_SIZE) {
-			if (follow_phys(vma, vma_start + i, 0, &prot, &paddr))
+		/*
+		 * free vma range from vstart to end, page by page
+		 * using the pfn from pte
+		 */
+		for (i = vstart; i < vend; i += PAGE_SIZE) {
+			if (follow_phys(vma, i, 0, &prot, &paddr))
 				continue;
 
 			free_pfn_range(paddr, PAGE_SIZE);
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 8e6d0ca..a325dc1 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -328,7 +328,8 @@ static inline int track_pfn_vma_copy(struct vm_area_struct *vma)
  * can be for the entire vma (in which case size can be zero).
  */
 static inline void untrack_pfn_vma(struct vm_area_struct *vma,
-					unsigned long pfn, unsigned long size)
+				unsigned long pfn, unsigned long size,
+				unsigned long vstart, unsigned long vend)
 {
 }
 #else
@@ -336,7 +337,8 @@ extern int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
 				unsigned long pfn, unsigned long size);
 extern int track_pfn_vma_copy(struct vm_area_struct *vma);
 extern void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
-				unsigned long size);
+				unsigned long size,
+				unsigned long vstart, unsigned long vend);
 #endif
 
 #endif /* !__ASSEMBLY__ */
diff --git a/mm/memory.c b/mm/memory.c
index cf6873e..6e111c5 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -983,7 +983,7 @@ unsigned long unmap_vmas(struct mmu_gather **tlbp,
 			*nr_accounted += (end - start) >> PAGE_SHIFT;
 
 		if (unlikely(is_pfn_mapping(vma)))
-			untrack_pfn_vma(vma, 0, 0);
+			untrack_pfn_vma(vma, 0, 0, start, end);
 
 		while (start != end) {
 			if (!tlb_start_valid) {
@@ -1537,7 +1537,7 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 	ret = insert_pfn(vma, addr, pfn, pgprot);
 
 	if (ret)
-		untrack_pfn_vma(vma, pfn, PAGE_SIZE);
+		untrack_pfn_vma(vma, pfn, PAGE_SIZE, 0, 0);
 
 	return ret;
 }
@@ -1702,7 +1702,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
 	} while (pgd++, addr = next, addr != end);
 
 	if (err)
-		untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
+		untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size), 0, 0);
 
 	return err;
 }
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