[PATCH 05/43] mm: Expand vma iterator interface.

From: Liam Howlett <liam.howlett@oracle.com>
To: "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Liam Howlett <liam.howlett@oracle.com>,
	Liam Howlett <liam.howlett@oracle.com>
Subject: [PATCH 05/43] mm: Expand vma iterator interface.
Date: Tue, 29 Nov 2022 16:44:21 +0000	[thread overview]
Message-ID: <20221129164352.3374638-6-Liam.Howlett@oracle.com> (raw)
In-Reply-To: <20221129164352.3374638-1-Liam.Howlett@oracle.com>

From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

Add wrappers for the maple tree to the vma iterator.  This will provide
type safety at compile time.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
 include/linux/mm.h       | 46 ++++++++++++++++++++++---
 include/linux/mm_types.h |  4 +--
 mm/mmap.c                | 74 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 117 insertions(+), 7 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8bbcccbc5565..2d3a49ba2261 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -664,16 +664,16 @@ static inline bool vma_is_accessible(struct vm_area_struct *vma)
 static inline
 struct vm_area_struct *vma_find(struct vma_iterator *vmi, unsigned long max)
 {
-	return mas_find(&vmi->mas, max);
+	return mas_find(&vmi->mas, max - 1);
 }
 
 static inline struct vm_area_struct *vma_next(struct vma_iterator *vmi)
 {
 	/*
-	 * Uses vma_find() to get the first VMA when the iterator starts.
+	 * Uses mas_find() to get the first VMA when the iterator starts.
 	 * Calling mas_next() could skip the first entry.
 	 */
-	return vma_find(vmi, ULONG_MAX);
+	return mas_find(&vmi->mas, ULONG_MAX);
 }
 
 static inline struct vm_area_struct *vma_prev(struct vma_iterator *vmi)
@@ -686,12 +686,50 @@ static inline unsigned long vma_iter_addr(struct vma_iterator *vmi)
 	return vmi->mas.index;
 }
 
+static inline unsigned long vma_iter_end(struct vma_iterator *vmi)
+{
+	return vmi->mas.last + 1;
+}
+static inline int vma_iter_bulk_alloc(struct vma_iterator *vmi,
+				      unsigned long count)
+{
+	return mas_expected_entries(&vmi->mas, count);
+}
+
+/* Free any unused preallocations */
+static inline void vma_iter_free(struct vma_iterator *vmi)
+{
+	mas_destroy(&vmi->mas);
+}
+
+static inline int vma_iter_bulk_store(struct vma_iterator *vmi,
+				      struct vm_area_struct *vma)
+{
+	vmi->mas.index = vma->vm_start;
+	vmi->mas.last = vma->vm_end - 1;
+	mas_store(&vmi->mas, vma);
+	if (unlikely(mas_is_err(&vmi->mas)))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static inline void vma_iter_invalidate(struct vma_iterator *vmi)
+{
+	mas_pause(&vmi->mas);
+}
+
+static inline void vma_iter_set(struct vma_iterator *vmi, unsigned long addr)
+{
+	mas_set(&vmi->mas, addr);
+}
+
 #define for_each_vma(__vmi, __vma)					\
 	while (((__vma) = vma_next(&(__vmi))) != NULL)
 
 /* The MM code likes to work with exclusive end addresses */
 #define for_each_vma_range(__vmi, __vma, __end)				\
-	while (((__vma) = vma_find(&(__vmi), (__end) - 1)) != NULL)
+	while (((__vma) = vma_find(&(__vmi), (__end))) != NULL)
 
 #ifdef CONFIG_SHMEM
 /*
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 500e536796ca..faff2cc005c9 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -819,9 +819,7 @@ struct vma_iterator {
 static inline void vma_iter_init(struct vma_iterator *vmi,
 		struct mm_struct *mm, unsigned long addr)
 {
-	vmi->mas.tree = &mm->mm_mt;
-	vmi->mas.index = addr;
-	vmi->mas.node = MAS_START;
+	mas_init(&vmi->mas, &mm->mm_mt, addr);
 }
 
 struct mmu_gather;
diff --git a/mm/mmap.c b/mm/mmap.c
index c3c5c1d6103d..8f24021ef5b5 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -144,6 +144,80 @@ static void remove_vma(struct vm_area_struct *vma)
 	vm_area_free(vma);
 }
 
+static inline struct vm_area_struct *vma_iter_load(struct vma_iterator *vmi)
+{
+	return mas_walk(&vmi->mas);
+}
+
+static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi,
+						    unsigned long min)
+{
+	return mas_prev(&vmi->mas, min);
+}
+
+static inline int vma_iter_prealloc(struct vma_iterator *vmi,
+				    struct vm_area_struct *vma)
+{
+	return mas_preallocate(&vmi->mas, vma, GFP_KERNEL);
+}
+
+/* Store a VMA with preallocated memory */
+static inline void vma_iter_store(struct vma_iterator *vmi,
+				  struct vm_area_struct *vma)
+{
+	if (WARN_ON(vmi->mas.node != MAS_START && vmi->mas.index > vma->vm_start)) {
+		printk("%lu > %lu\n", vmi->mas.index, vma->vm_start);
+		printk("store of vma %lu-%lu", vma->vm_start, vma->vm_end);
+		printk("into slot    %lu-%lu", vmi->mas.index, vmi->mas.last);
+		mt_dump(vmi->mas.tree);
+	}
+	if (WARN_ON(vmi->mas.node != MAS_START && vmi->mas.last <  vma->vm_start)) {
+		printk("%lu < %lu\n", vmi->mas.last, vma->vm_start);
+		printk("store of vma %lu-%lu", vma->vm_start, vma->vm_end);
+		printk("into slot    %lu-%lu", vmi->mas.index, vmi->mas.last);
+		mt_dump(vmi->mas.tree);
+	}
+
+	if (vmi->mas.node != MAS_START &&
+	    ((vmi->mas.index > vma->vm_start) || (vmi->mas.last < vma->vm_start)))
+		vma_iter_invalidate(vmi);
+
+	vmi->mas.index = vma->vm_start;
+	vmi->mas.last = vma->vm_end - 1;
+	mas_store_prealloc(&vmi->mas, vma);
+}
+
+static inline void vma_iter_clear(struct vma_iterator *vmi,
+				  unsigned long start, unsigned long end)
+{
+	mas_set_range(&vmi->mas, start, end - 1);
+	mas_store_prealloc(&vmi->mas, NULL);
+}
+
+static inline int vma_iter_store_gfp(struct vma_iterator *vmi,
+			struct vm_area_struct *vma, gfp_t gfp)
+{
+	vmi->mas.index = vma->vm_start;
+	vmi->mas.last = vma->vm_end - 1;
+	mas_store_gfp(&vmi->mas, vma, gfp);
+	if (unlikely(mas_is_err(&vmi->mas)))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static inline int vma_iter_clear_gfp(struct vma_iterator *vmi,
+			unsigned long start, unsigned long end, gfp_t gfp)
+{
+	vmi->mas.index = start;
+	vmi->mas.last = end - 1;
+	mas_store_gfp(&vmi->mas, NULL, gfp);
+	if (unlikely(mas_is_err(&vmi->mas)))
+		return -ENOMEM;
+
+	return 0;
+}
+
 /*
  * check_brk_limits() - Use platform specific check of range & verify mlock
  * limits.
-- 
2.35.1
