linux-kernel - [PATCH 1/3] mm: Drop first_index/last_index in zap

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Date:   Mon,  7 Dec 2020 21:50:20 -0500
From:   Peter Xu <peterx@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     Andrea Arcangeli <aarcange@...hat.com>, peterx@...hat.com,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 1/3] mm: Drop first_index/last_index in zap_details

The first_index/last_index parameters in zap_details are actually only used in
unmap_mapping_range_tree().  At the meantime, this function is only called by
unmap_mapping_pages() once.  Instead of passing these two variables through the
whole stack of page zapping code, remove them from zap_details and let them
simply be parameters of unmap_mapping_range_tree(), which is inlined.

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 include/linux/mm.h |  2 --
 mm/memory.c        | 20 ++++++++++----------
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 16b799a0522c..5d977e484095 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1625,8 +1625,6 @@ extern void user_shm_unlock(size_t, struct user_struct *);
  */
 struct zap_details {
 	struct address_space *check_mapping;	/* Check page->mapping if set */
-	pgoff_t	first_index;			/* Lowest page->index to unmap */
-	pgoff_t last_index;			/* Highest page->index to unmap */
 };
 
 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
diff --git a/mm/memory.c b/mm/memory.c
index eeae590e526a..70d57c39380d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3136,20 +3136,20 @@ static void unmap_mapping_range_vma(struct vm_area_struct *vma,
 }
 
 static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
+					    pgoff_t first_index,
+					    pgoff_t last_index,
 					    struct zap_details *details)
 {
 	struct vm_area_struct *vma;
 	pgoff_t vba, vea, zba, zea;
 
-	vma_interval_tree_foreach(vma, root,
-			details->first_index, details->last_index) {
-
+	vma_interval_tree_foreach(vma, root, first_index, last_index) {
 		vba = vma->vm_pgoff;
 		vea = vba + vma_pages(vma) - 1;
-		zba = details->first_index;
+		zba = first_index;
 		if (zba < vba)
 			zba = vba;
-		zea = details->last_index;
+		zea = last_index;
 		if (zea > vea)
 			zea = vea;
 
@@ -3175,17 +3175,17 @@ static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
 void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
 		pgoff_t nr, bool even_cows)
 {
+	pgoff_t	first_index = start, last_index = start + nr - 1;
 	struct zap_details details = { };
 
 	details.check_mapping = even_cows ? NULL : mapping;
-	details.first_index = start;
-	details.last_index = start + nr - 1;
-	if (details.last_index < details.first_index)
-		details.last_index = ULONG_MAX;
+	if (last_index < first_index)
+		last_index = ULONG_MAX;
 
 	i_mmap_lock_write(mapping);
 	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
-		unmap_mapping_range_tree(&mapping->i_mmap, &details);
+		unmap_mapping_range_tree(&mapping->i_mmap, first_index,
+					 last_index, &details);
 	i_mmap_unlock_write(mapping);
 }
 
-- 
2.26.2