linux-kernel - [PATCH 07/10] huge mm: move_huge_pmd does not need new

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Date:	Tue, 5 Apr 2016 13:51:15 -0700 (PDT)
From:	Hugh Dickins <hughd@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andres Lagar-Cavilla <andreslc@...gle.com>,
	Yang Shi <yang.shi@...aro.org>, Ning Qu <quning@...il.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH 07/10] huge mm: move_huge_pmd does not need new_vma

Remove move_huge_pmd()'s redundant new_vma arg: all it was used for was
a VM_NOHUGEPAGE check on new_vma flags, but the new_vma is cloned from
the old vma, so a trans_huge_pmd in the new_vma will be as acceptable
as it was in the old vma, alignment and size permitting.

Signed-off-by: Hugh Dickins <hughd@...gle.com>
---
 include/linux/huge_mm.h |    4 +---
 mm/huge_memory.c        |    7 ++-----
 mm/mremap.c             |    5 ++---
 3 files changed, 5 insertions(+), 11 deletions(-)

--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -28,9 +28,7 @@ extern int zap_huge_pmd(struct mmu_gathe
 extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 			unsigned long addr, unsigned long end,
 			unsigned char *vec);
-extern bool move_huge_pmd(struct vm_area_struct *vma,
-			 struct vm_area_struct *new_vma,
-			 unsigned long old_addr,
+extern 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);
 extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1704,20 +1704,17 @@ int zap_huge_pmd(struct mmu_gather *tlb,
 	return 1;
 }
 
-bool move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
-		  unsigned long old_addr,
+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)
 {
 	spinlock_t *old_ptl, *new_ptl;
 	pmd_t pmd;
-
 	struct mm_struct *mm = vma->vm_mm;
 
 	if ((old_addr & ~HPAGE_PMD_MASK) ||
 	    (new_addr & ~HPAGE_PMD_MASK) ||
-	    old_end - old_addr < HPAGE_PMD_SIZE ||
-	    (new_vma->vm_flags & VM_NOHUGEPAGE))
+	    old_end - old_addr < HPAGE_PMD_SIZE)
 		return false;
 
 	/*
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -198,9 +198,8 @@ unsigned long move_page_tables(struct vm
 				/* See comment in move_ptes() */
 				if (need_rmap_locks)
 					anon_vma_lock_write(vma->anon_vma);
-				moved = move_huge_pmd(vma, new_vma, old_addr,
-						    new_addr, old_end,
-						    old_pmd, new_pmd);
+				moved = move_huge_pmd(vma, old_addr, new_addr,
+						    old_end, old_pmd, new_pmd);
 				if (need_rmap_locks)
 					anon_vma_unlock_write(vma->anon_vma);
 				if (moved) {