From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: akpm@linux-foundation.org, Rik van Riel <riel@surriel.com>,
Mel Gorman <mgorman@techsingularity.net>,
paulus@ozlabs.org, benh@kernel.crashing.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: [PATCH V3 2/3] mm/ksm: Handle protnone saved writes when making page write protect
Date: Sun, 19 Feb 2017 15:33:44 +0530 [thread overview]
Message-ID: <1487498625-10891-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com> (raw)
In-Reply-To: <1487498625-10891-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
Without this KSM will consider the page write protected, but a numa fault can
later mark the page writable. This can result in memory corruption.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
include/asm-generic/pgtable.h | 8 ++++++++
mm/ksm.c | 9 +++++++--
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index b6f3a8a4b738..8c8ba48bef0b 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -200,6 +200,10 @@ 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
@@ -208,6 +212,10 @@ 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 9ae6011a41f8..768202831578 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -872,7 +872,8 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
if (!ptep)
goto out_mn;
- if (pte_write(*ptep) || pte_dirty(*ptep)) {
+ if (pte_write(*ptep) || pte_dirty(*ptep) ||
+ (pte_protnone(*ptep) && pte_savedwrite(*ptep))) {
pte_t entry;
swapped = PageSwapCache(page);
@@ -897,7 +898,11 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
}
if (pte_dirty(entry))
set_page_dirty(page);
- entry = pte_mkclean(pte_wrprotect(entry));
+
+ if (pte_protnone(entry))
+ entry = pte_mkclean(pte_clear_savedwrite(entry));
+ else
+ entry = pte_mkclean(pte_wrprotect(entry));
set_pte_at_notify(mm, addr, ptep, entry);
}
*orig_pte = *ptep;
--
2.7.4
--
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next prev parent reply other threads:[~2017-02-19 10:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-19 10:03 [PATCH V3 0/3] Numabalancing preserve write fix Aneesh Kumar K.V
2017-02-19 10:03 ` [PATCH V3 1/3] mm/autonuma: Let architecture override how the write bit should be stashed in a protnone pte Aneesh Kumar K.V
2017-02-19 10:03 ` Aneesh Kumar K.V [this message]
2017-02-19 10:03 ` [PATCH V3 3/3] powerpc/mm/autonuma: Switch ppc64 to its own implementeation of saved write Aneesh Kumar K.V
2017-02-19 10:25 ` [PATCH V3 0/3] Numabalancing preserve write fix Aneesh Kumar K.V
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