linux-kernel - [PATCH 1/2] mm: move vma_is_anonymous check within pmd_move_must

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Date:   Mon,  7 Nov 2016 14:04:40 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:     akpm@...ux-foundation.org, benh@...nel.crashing.org,
        paulus@...ba.org, mpe@...erman.id.au,
        "Kirill A . Shutemov" <kirill@...temov.name>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: [PATCH 1/2] mm: move vma_is_anonymous check within pmd_move_must_withdraw

Architectures like ppc64 want to use page table deposit/withraw
even with huge pmd dax entries. Allow arch to override the
vma_is_anonymous check by moving that to pmd_move_must_withdraw
function

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
---
 include/asm-generic/pgtable.h | 12 ------------
 mm/huge_memory.c              | 17 +++++++++++++++--
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index c4f8fd2fd384..324990273ad2 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -653,18 +653,6 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
 }
 #endif
 
-#ifndef pmd_move_must_withdraw
-static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
-					 spinlock_t *old_pmd_ptl)
-{
-	/*
-	 * With split pmd lock we also need to move preallocated
-	 * PTE page table if new_pmd is on different PMD page table.
-	 */
-	return new_pmd_ptl != old_pmd_ptl;
-}
-#endif
-
 /*
  * This function is meant to be used by sites walking pagetables with
  * the mmap_sem hold in read mode to protect against MADV_DONTNEED and
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index cdcd25cb30fe..1ac1b0ca63c4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1424,6 +1424,20 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	return 1;
 }
 
+#ifndef pmd_move_must_withdraw
+static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
+					 spinlock_t *old_pmd_ptl)
+{
+	/*
+	 * With split pmd lock we also need to move preallocated
+	 * PTE page table if new_pmd is on different PMD page table.
+	 *
+	 * We also don't deposit and withdraw tables for file pages.
+	 */
+	return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
+}
+#endif
+
 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		  unsigned long new_addr, unsigned long old_end,
 		  pmd_t *old_pmd, pmd_t *new_pmd)
@@ -1458,8 +1472,7 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
 		VM_BUG_ON(!pmd_none(*new_pmd));
 
-		if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
-				vma_is_anonymous(vma)) {
+		if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
 			pgtable_t pgtable;
 			pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
 			pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
-- 
2.10.2