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SubjectRe: [PATCH] mm: tracking dirty pages -v6
1. The case that a vma is shared is not likely.

2. Typo fix in mmap.c

3. This may be a bit controversial but it does not seem to
make sense to use the update_mmu_cache macro when we reuse
the page. We are only fiddling around with the protections,
the dirty and accessed bits.

With the call to update_mmu_cache the way of using the macros
would be different from mprotect() and page_mkclean(). I'd
rather have everything work the same way. If this breaks on some
arches then also mprotect and page_mkclean() are broken.
The use of mprotect() is rare, we may have breakage in some
arches that we just have not seen yet.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c 2006-06-08 09:12:13.000000000 -0700
+++ linux-2.6/mm/memory.c 2006-06-08 09:50:17.000000000 -0700
@@ -1452,7 +1452,7 @@ static int do_wp_page(struct mm_struct *
if (!old_page)
goto gotten;

- if (vma->vm_flags & VM_SHARED) {
+ if (unlikely(vma->vm_flags & VM_SHARED)) {
reuse = 1;
dirty_page = old_page;
get_page(dirty_page);
@@ -1466,7 +1466,6 @@ static int do_wp_page(struct mm_struct *
entry = pte_mkyoung(orig_pte);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
ptep_set_access_flags(vma, address, page_table, entry, 1);
- update_mmu_cache(vma, address, entry);
lazy_mmu_prot_update(entry);
ret |= VM_FAULT_WRITE;
goto unlock;
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c 2006-06-08 09:15:54.000000000 -0700
+++ linux-2.6/mm/mmap.c 2006-06-08 09:17:41.000000000 -0700
@@ -1092,7 +1092,7 @@ munmap_back:
* f_op->mmap() - modifies vm_page_prot; but will not reset
* from vm_flags.
*
- * Hence between the two calls (here) it is save to modify
+ * Hence between the two calls (here) it is safe to modify
* vm_page_prot depending on backing_dev_info capabilities.
*
* shmem_backing_dev_info does have BDI_CAP_NO_ACCT_DIRTY.
-
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