[v5 12/15] mm: explicitly zero pagetable memory

[Pavel Tatashin]

Soon vmemmap_alloc_block() will no longer zero the block, so zero memory
at its call sites for everything except struct pages.  Struct page memory
is zero'd by struct page initialization.

Signed-off-by: Pavel Tatashin <pasha.tatas...@oracle.com>
Reviewed-by: Steven Sistare <steven.sist...@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jor...@oracle.com>
Reviewed-by: Bob Picco <bob.pi...@oracle.com>
---
 mm/sparse-vmemmap.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index c50b1a14d55e..d40c721ab19f 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -191,6 +191,7 @@ pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned 
long addr, int node)
                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
                if (!p)
                        return NULL;
+               memset(p, 0, PAGE_SIZE);
                pmd_populate_kernel(&init_mm, pmd, p);
        }
        return pmd;
@@ -203,6 +204,7 @@ pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned 
long addr, int node)
                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
                if (!p)
                        return NULL;
+               memset(p, 0, PAGE_SIZE);
                pud_populate(&init_mm, pud, p);
        }
        return pud;
@@ -215,6 +217,7 @@ p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned 
long addr, int node)
                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
                if (!p)
                        return NULL;
+               memset(p, 0, PAGE_SIZE);
                p4d_populate(&init_mm, p4d, p);
        }
        return p4d;
@@ -227,6 +230,7 @@ pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, 
int node)
                void *p = vmemmap_alloc_block(PAGE_SIZE, node);
                if (!p)
                        return NULL;
+               memset(p, 0, PAGE_SIZE);
                pgd_populate(&init_mm, pgd, p);
        }
        return pgd;
-- 
2.13.4