linux-kernel - [PATCH] mm/mmap: leave adjust_next as virtual address instead of page frame number

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Message-Id: <20200828081031.11306-1-richard.weiyang@linux.alibaba.com>
Date:   Fri, 28 Aug 2020 16:10:31 +0800
From:   Wei Yang <richard.weiyang@...ux.alibaba.com>
To:     akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Wei Yang <richard.weiyang@...ux.alibaba.com>
Subject: [PATCH] mm/mmap: leave adjust_next as virtual address instead of page frame number

Instead of convert adjust_next between virtual address and page frame
number, let's just store the virtual address into adjust_next.

Also, this patch fixes one typo in the comment of
vma_adjust_trans_huge().

Signed-off-by: Wei Yang <richard.weiyang@...ux.alibaba.com>
---
 mm/huge_memory.c | 4 ++--
 mm/mmap.c        | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 78c84bee7e29..2c633ba14440 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2300,13 +2300,13 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
 
 	/*
 	 * If we're also updating the vma->vm_next->vm_start, if the new
-	 * vm_next->vm_start isn't page aligned and it could previously
+	 * vm_next->vm_start isn't hpage aligned and it could previously
 	 * contain an hugepage: check if we need to split an huge pmd.
 	 */
 	if (adjust_next > 0) {
 		struct vm_area_struct *next = vma->vm_next;
 		unsigned long nstart = next->vm_start;
-		nstart += adjust_next << PAGE_SHIFT;
+		nstart += adjust_next;
 		if (nstart & ~HPAGE_PMD_MASK &&
 		    (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
 		    (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
diff --git a/mm/mmap.c b/mm/mmap.c
index 90b1298d4222..e4c9bbfd4103 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -758,7 +758,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 			 * vma expands, overlapping part of the next:
 			 * mprotect case 5 shifting the boundary up.
 			 */
-			adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
+			adjust_next = (end - next->vm_start);
 			exporter = next;
 			importer = vma;
 			VM_WARN_ON(expand != importer);
@@ -768,7 +768,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 			 * split_vma inserting another: so it must be
 			 * mprotect case 4 shifting the boundary down.
 			 */
-			adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
+			adjust_next = -(vma->vm_end - end);
 			exporter = vma;
 			importer = next;
 			VM_WARN_ON(expand != importer);
@@ -840,8 +840,8 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 	}
 	vma->vm_pgoff = pgoff;
 	if (adjust_next) {
-		next->vm_start += adjust_next << PAGE_SHIFT;
-		next->vm_pgoff += adjust_next;
+		next->vm_start += adjust_next;
+		next->vm_pgoff += adjust_next >> PAGE_SHIFT;
 	}
 
 	if (root) {
-- 
2.20.1 (Apple Git-117)