Commit a00e7bea authored Jun 20, 2013 by Aneesh Kumar K.V Committed by Benjamin Herrenschmidt Jun 21, 2013

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>

parent 7888b4dd

arch/powerpc/mm/pgtable.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -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));
		}