pve-kernel-thunderx/swapops-0001-Revert-mm-ksm-handle-protnone-saved-writes-when-maki.patch
Fabian Grünbichler 2b834b083d add proposed fix for LP#1674838
Patches and rationale by Seth Forshee[1]:

My testing shows that the "POWER9: Additional power9
patches" patches are responsible, two of them in particular:

 - mm: introduce page_vma_mapped_walk()
 - mm, ksm: convert write_protect_page() to use page_vma_mapped_walk()

These patches don't appear to be included for any
functionality they provide, but rather to make "mm/ksm:
handle protnone saved writes when making page write protect"
a clean cherry pick instead of a backport. But the backport
isn't that difficult, so as far as I can tell we can do away
with the other two patches.

1: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1674838/comments/108
2017-05-05 09:12:20 +02:00

70 lines
2.3 KiB
Diff

From b4cf3c107f8f1d2da2b606e9d08e241be7000d65 Mon Sep 17 00:00:00 2001
From: Seth Forshee <seth.forshee@canonical.com>
Date: Wed, 3 May 2017 08:34:47 -0500
Subject: [PATCH 1/4] Revert "mm/ksm: handle protnone saved writes when making
page write protect"
This reverts commit c228a1037cd6bd0064472ea282e3730a342d6fca.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
---
include/asm-generic/pgtable.h | 8 --------
mm/ksm.c | 9 ++-------
2 files changed, 2 insertions(+), 15 deletions(-)
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 8c8ba48bef0b..b6f3a8a4b738 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -200,10 +200,6 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
#define pte_mk_savedwrite pte_mkwrite
#endif
-#ifndef pte_clear_savedwrite
-#define pte_clear_savedwrite pte_wrprotect
-#endif
-
#ifndef pmd_savedwrite
#define pmd_savedwrite pmd_write
#endif
@@ -212,10 +208,6 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
#define pmd_mk_savedwrite pmd_mkwrite
#endif
-#ifndef pmd_clear_savedwrite
-#define pmd_clear_savedwrite pmd_wrprotect
-#endif
-
#ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline void pmdp_set_wrprotect(struct mm_struct *mm,
diff --git a/mm/ksm.c b/mm/ksm.c
index abc05187168a..9dd2e58fb6dc 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -880,8 +880,7 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))
goto out_unlock;
- if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte) ||
- (pte_protnone(*pvmw.pte) && pte_savedwrite(*pvmw.pte))) {
+ if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte)) {
pte_t entry;
swapped = PageSwapCache(page);
@@ -906,11 +905,7 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
}
if (pte_dirty(entry))
set_page_dirty(page);
-
- if (pte_protnone(entry))
- entry = pte_mkclean(pte_clear_savedwrite(entry));
- else
- entry = pte_mkclean(pte_wrprotect(entry));
+ entry = pte_mkclean(pte_wrprotect(entry));
set_pte_at_notify(mm, pvmw.address, pvmw.pte, entry);
}
*orig_pte = *pvmw.pte;
--
2.7.4