From 458f7920f9b1e6c313944d498c440f8599b8a136 Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Mon, 10 Jul 2017 15:50:21 -0700 Subject: [PATCH] mm/kasan/kasan_init.c: use kasan_zero_pud for p4d table There is missing optimization in zero_p4d_populate() that can save some memory when mapping zero shadow. Implement it like as others. Link: http://lkml.kernel.org/r/1494829255-23946-1-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Joonsoo Kim Acked-by: Andrey Ryabinin Cc: "Kirill A . Shutemov" Cc: Alexander Potapenko Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/kasan/kasan_init.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/mm/kasan/kasan_init.c b/mm/kasan/kasan_init.c index b96a5f773d88..554e4c0f23a2 100644 --- a/mm/kasan/kasan_init.c +++ b/mm/kasan/kasan_init.c @@ -118,6 +118,18 @@ static void __init zero_p4d_populate(pgd_t *pgd, unsigned long addr, do { next = p4d_addr_end(addr, end); + if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) { + pud_t *pud; + pmd_t *pmd; + + p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud)); + pud = pud_offset(p4d, addr); + pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd)); + pmd = pmd_offset(pud, addr); + pmd_populate_kernel(&init_mm, pmd, + lm_alias(kasan_zero_pte)); + continue; + } if (p4d_none(*p4d)) { p4d_populate(&init_mm, p4d, -- 2.30.2