From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: benh@kernel.crashing.org, paulus@samba.org, dwg@au1.ibm.com
Cc: linuxppc-dev@lists.ozlabs.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: [PATCH -V8 18/18] powerpc: disable assert_pte_locked for collapse_huge_page
Date: Sun, 12 May 2013 21:44:25 +0530 [thread overview]
Message-ID: <1368375265-19593-19-git-send-email-aneesh.kumar@linux.vnet.ibm.com> (raw)
In-Reply-To: <1368375265-19593-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
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>
---
arch/powerpc/mm/pgtable.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 214130a..edda589 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));
}
--
1.8.1.2
prev parent reply other threads:[~2013-05-12 16:14 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-12 16:14 [PATCH -V8 00/18] THP support for PPC64 Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 01/18] powerpc/mm: Use the correct mask value when looking at pgtable address Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 02/18] mm/THP: Use pmd_populate to update the pmd with pgtable_t pointer Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 03/18] mm/THP: Use the right function when updating access flags Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 04/18] mm/THP: Add pmd args to pgtable deposit and withdraw APIs Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 05/18] mm/THP: withdraw the pgtable after pmdp related operations Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 06/18] mm/THP: Don't use HPAGE_SHIFT in transparent hugepage code Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 07/18] mm/THP: deposit the transpare huge pgtable before set_pmd Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 08/18] powerpc/THP: Double the PMD table size for THP Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 09/18] powerpc/THP: Implement transparent hugepages for ppc64 Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 10/18] powerpc: move find_linux_pte_or_hugepte and gup_hugepte to common code Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 11/18] powerpc: Update find_linux_pte_or_hugepte to handle transparent hugepages Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 12/18] powerpc: Replace find_linux_pte with find_linux_pte_or_hugepte Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 13/18] powerpc: Update gup_pmd_range to handle transparent hugepages Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 14/18] powerpc/THP: Add code to handle HPTE faults for hugepages Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 15/18] powerpc: Make linux pagetable walk safe with THP enabled Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 16/18] powerpc/THP: Enable THP on PPC64 Aneesh Kumar K.V
2013-05-12 16:14 ` [PATCH -V8 17/18] powerpc: Optimize hugepage invalidate Aneesh Kumar K.V
2013-05-12 16:14 ` Aneesh Kumar K.V [this message]
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