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authorMel Gorman <mgorman@suse.de>2015-02-12 14:58:35 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 18:54:08 -0800
commite944fd67b625c02bda4a78ddf85e413c5e401474 (patch)
tree73430e339d1d27b315b3789bc0a271882ecf9174 /mm/mprotect.c
parent21d9ee3eda7792c45880b2f11bff8e95c9a061fb (diff)
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mm: numa: do not trap faults on the huge zero page
Faults on the huge zero page are pointless and there is a BUG_ON to catch them during fault time. This patch reintroduces a check that avoids marking the zero page PAGE_NONE. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Jones <davej@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mprotect.c')
-rw-r--r--mm/mprotect.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 76824d73380d..dd599fc235c2 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -76,6 +76,18 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
if (pte_present(oldpte)) {
pte_t ptent;
+ /*
+ * Avoid trapping faults against the zero or KSM
+ * pages. See similar comment in change_huge_pmd.
+ */
+ if (prot_numa) {
+ struct page *page;
+
+ page = vm_normal_page(vma, addr, oldpte);
+ if (!page || PageKsm(page))
+ continue;
+ }
+
ptent = ptep_modify_prot_start(mm, addr, pte);
ptent = pte_modify(ptent, newprot);
@@ -142,7 +154,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
split_huge_page_pmd(vma, addr, pmd);
else {
int nr_ptes = change_huge_pmd(vma, pmd, addr,
- newprot);
+ newprot, prot_numa);
if (nr_ptes) {
if (nr_ptes == HPAGE_PMD_NR) {