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authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2013-06-20 14:30:24 +0530
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-06-21 16:01:57 +1000
commita00e7bea0dde6a44b9bbe84f30b731d9ec73858b (patch)
tree295e7fa1b52b6dbf846e67f408fd42fb44b7c773 /arch
parent7888b4ddb44dccd68bc20d0dc4425707dff88c72 (diff)
powerpc: disable assert_pte_locked for collapse_huge_page
With THP we set pmd to none, before we do pte_clear. Hence we can't walk page table to get the pte lock ptr and verify whether it is locked. THP do take pte lock before calling pte_clear. So we don't change the locking rules here. It is that we can't use page table walking to check whether pte locks are held with THP. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/mm/pgtable.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 214130a4edc..edda589795c 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -235,6 +235,14 @@ void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
pud = pud_offset(pgd, addr);
BUG_ON(pud_none(*pud));
pmd = pmd_offset(pud, addr);
+ /*
+ * khugepaged to collapse normal pages to hugepage, first set
+ * pmd to none to force page fault/gup to take mmap_sem. After
+ * pmd is set to none, we do a pte_clear which does this assertion
+ * so if we find pmd none, return.
+ */
+ if (pmd_none(*pmd))
+ return;
BUG_ON(!pmd_present(*pmd));
assert_spin_locked(pte_lockptr(mm, pmd));
}