[RFC PATCH 1/3] mm/thp: Use pmdp_splitting_flush_notify to clear pmd on splitting

From: Aneesh Kumar K.V
Date: Thu Apr 30 2015 - 04:28:12 EST


Some arch may require an explicit IPI before a THP PMD split. This
ensures that a local_irq_disable can prevent a parallel THP PMD split.
So use new function which arch can override

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
include/asm-generic/pgtable.h | 5 +++++
mm/huge_memory.c | 7 ++++---
mm/pgtable-generic.c | 11 +++++++++++
3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index fe617b7e4be6..d091a666f5b1 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -184,6 +184,11 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm,
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif

+#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH_NOTIFY
+extern void pmdp_splitting_flush_notify(struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmdp);
+#endif
+
#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
pgtable_t pgtable);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index cce4604c192f..81e9578bf43a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2606,9 +2606,10 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,

write = pmd_write(*pmd);
young = pmd_young(*pmd);
-
- /* leave pmd empty until pte is filled */
- pmdp_clear_flush_notify(vma, haddr, pmd);
+ /*
+ * leave pmd empty until pte is filled.
+ */
+ pmdp_splitting_flush_notify(vma, haddr, pmd);

pgtable = pgtable_trans_huge_withdraw(mm, pmd);
pmd_populate(mm, &_pmd, pgtable);
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 2fe699cedd4d..0fc1f5a06979 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -7,6 +7,7 @@
*/

#include <linux/pagemap.h>
+#include <linux/mmu_notifier.h>
#include <asm/tlb.h>
#include <asm-generic/pgtable.h>

@@ -184,3 +185,13 @@ void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
+
+#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH_NOTIFY
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+void pmdp_splitting_flush_notify(struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmdp)
+{
+ pmdp_clear_flush_notify(vma, address, pmdp);
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
--
2.1.4

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