linux-kernel - [v6 12/15] mm: explicitly zero pagetable memory

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Message-Id: <1502138329-123460-13-git-send-email-pasha.tatashin@oracle.com>
Date:   Mon,  7 Aug 2017 16:38:46 -0400
From:   Pavel Tatashin <pasha.tatashin@...cle.com>
To:     linux-kernel@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        x86@...nel.org, kasan-dev@...glegroups.com, borntraeger@...ibm.com,
        heiko.carstens@...ibm.com, davem@...emloft.net,
        willy@...radead.org, mhocko@...nel.org, ard.biesheuvel@...aro.org,
        will.deacon@....com, catalin.marinas@....com, sam@...nborg.org
Subject: [v6 12/15] mm: explicitly zero pagetable memory

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.tatashin@...cle.com>
Reviewed-by: Steven Sistare <steven.sistare@...cle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@...cle.com>
Reviewed-by: Bob Picco <bob.picco@...cle.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;
-- 
2.14.0