The patch titled
Subject: thp: copy_huge_pmd(): copy huge zero page
has been removed from the -mm tree. Its filename was
thp-copy_huge_pmd-copy-huge-zero-page.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: thp: copy_huge_pmd(): copy huge zero page
It's easy to copy huge zero page. Just set destination pmd to huge zero
page.
It's safe to copy huge zero page since we have none yet :-p
[rientjes@xxxxxxxxxx: fix comment]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff -puN mm/huge_memory.c~thp-copy_huge_pmd-copy-huge-zero-page mm/huge_memory.c
--- a/mm/huge_memory.c~thp-copy_huge_pmd-copy-huge-zero-page
+++ a/mm/huge_memory.c
@@ -708,6 +708,18 @@ static inline struct page *alloc_hugepag
}
#endif
+static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
+ struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd)
+{
+ pmd_t entry;
+ entry = pfn_pmd(huge_zero_pfn, vma->vm_page_prot);
+ entry = pmd_wrprotect(entry);
+ entry = pmd_mkhuge(entry);
+ set_pmd_at(mm, haddr, pmd, entry);
+ pgtable_trans_huge_deposit(mm, pgtable);
+ mm->nr_ptes++;
+}
+
int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, pmd_t *pmd,
unsigned int flags)
@@ -785,6 +797,16 @@ int copy_huge_pmd(struct mm_struct *dst_
pte_free(dst_mm, pgtable);
goto out_unlock;
}
+ /*
+ * mm->page_table_lock is enough to be sure that huge zero pmd is not
+ * under splitting since we don't split the page itself, only pmd to
+ * a page table.
+ */
+ if (is_huge_zero_pmd(pmd)) {
+ set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd);
+ ret = 0;
+ goto out_unlock;
+ }
if (unlikely(pmd_trans_splitting(pmd))) {
/* split huge page running from under us */
spin_unlock(&src_mm->page_table_lock);
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
origin.patch
linux-next.patch
x86-convert-update_mmu_cache-and-update_mmu_cache_pmd-to-functions.patch
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