On Wed, Nov 14, 2012 at 03:12:54PM -0800, David Rientjes wrote:

On Wed, 7 Nov 2012, Kirill A. Shutemov wrote:

quoted

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d767a7c..05490b3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c

@@ -1259,6 +1259,8 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 		pmd_t entry;
 		entry = pmdp_get_and_clear(mm, addr, pmd);
 		entry = pmd_modify(entry, newprot);
+		if (is_huge_zero_pmd(entry))
+			entry = pmd_wrprotect(entry);
 		set_pmd_at(mm, addr, pmd, entry);
 		spin_unlock(&vma->vm_mm->page_table_lock);
 		ret = 1;

Nack, this should be handled in pmd_modify().

I disagree. It means we will have to enable hzp per arch. Bad idea.

What's wrong with the check?

-- 
 Kirill A. Shutemov