lkml.org 
[lkml]   [2018]   [Oct]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 2/5] mm/cow: don't bother write protecting already write-protected huge pages
Date
This is the HugePage / THP equivalent for 1b2de5d039c8 ("mm/cow: don't
bother write protecting already write-protected pages").

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
mm/huge_memory.c | 14 ++++++++++----
mm/hugetlb.c | 2 +-
2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 58269f8ba7c4..0fb0e3025f98 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -973,8 +973,11 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
mm_inc_nr_ptes(dst_mm);
pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);

- pmdp_set_wrprotect(src_mm, addr, src_pmd);
- pmd = pmd_mkold(pmd_wrprotect(pmd));
+ if (pmd_write(pmd)) {
+ pmdp_set_wrprotect(src_mm, addr, src_pmd);
+ pmd = pmd_wrprotect(pmd);
+ }
+ pmd = pmd_mkold(pmd);
set_pmd_at(dst_mm, addr, dst_pmd, pmd);

ret = 0;
@@ -1064,8 +1067,11 @@ int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
/* No huge zero pud yet */
}

- pudp_set_wrprotect(src_mm, addr, src_pud);
- pud = pud_mkold(pud_wrprotect(pud));
+ if (pud_write(pud)) {
+ pudp_set_wrprotect(src_mm, addr, src_pud);
+ pud = pud_wrprotect(pud);
+ }
+ pud = pud_mkold(pud);
set_pud_at(dst_mm, addr, dst_pud, pud);

ret = 0;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 5c390f5a5207..54a4dcb6ee21 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3287,7 +3287,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
}
set_huge_swap_pte_at(dst, addr, dst_pte, entry, sz);
} else {
- if (cow) {
+ if (cow && huge_pte_write(entry)) {
/*
* No need to notify as we are downgrading page
* table protection not changing it to point
--
2.18.0
\
 
 \ /
  Last update: 2018-10-16 15:14    [W:0.045 / U:0.644 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site