[PATCH 1/8] vrange: Add basic data structure and functions

[John Stultz]

From: Minchan Kim <minchan@xxxxxxxxxx>

This patch adds vrange data structure(interval tree) and
related functions.

The vrange uses generic interval tree as main data structure
because it handles address range so generic interval tree
fits well for the purpose.

The add_vrange/remove_vrange are core functions for system call
will be introduced next patch.

1. add_vrange inserts new address range into interval tree.
   If new address range crosses over existing volatile range,
   existing volatile range will be expanded to cover new range.
   Then, if existing volatile range has purged state, new range
   will have a purged state.
   It's not good and we need more fine-grained purged state handling
   in a vrange(TODO)

   If new address range is inside existing range, we ignore it

2. remove_vrange removes address range
   Then, return a purged state of the address ranges.

This patch copied some part from John Stultz's work but different semantic.

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Android Kernel Team <kernel-team@xxxxxxxxxxx>
Cc: Robert Love <rlove@xxxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Dmitry Adamushko <dmitry.adamushko@xxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Neil Brown <neilb@xxxxxxx>
Cc: Andrea Righi <andrea@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Mike Hommey <mh@xxxxxxxxxxxx>
Cc: Taras Glek <tglek@xxxxxxxxxxx>
Cc: Dhaval Giani <dgiani@xxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx <linux-mm@xxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
[jstultz: Heavy rework and cleanups to make this infrastructure more
easily reused for both file and anonymous pages]
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
 include/linux/vrange.h       |  44 +++++++++++
 include/linux/vrange_types.h |  19 +++++
 init/main.c                  |   2 +
 lib/Makefile                 |   2 +-
 mm/Makefile                  |   2 +-
 mm/vrange.c                  | 181 +++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 248 insertions(+), 2 deletions(-)
 create mode 100644 include/linux/vrange.h
 create mode 100644 include/linux/vrange_types.h
 create mode 100644 mm/vrange.c

diff --git a/include/linux/vrange.h b/include/linux/vrange.h
new file mode 100644
index 0000000..2064cb0
--- /dev/null
+++ b/include/linux/vrange.h
@@ -0,0 +1,44 @@
+#ifndef _LINUX_VRANGE_H
+#define _LINUX_VRANGE_H
+
+#include <linux/vrange_types.h>
+#include <linux/mm.h>
+
+#define vrange_entry(ptr) \
+	container_of(ptr, struct vrange, node.rb)
+
+#ifdef CONFIG_MMU
+
+static inline void vrange_root_init(struct vrange_root *vroot, int type)
+{
+	vroot->type = type;
+	vroot->v_rb = RB_ROOT;
+	mutex_init(&vroot->v_lock);
+}
+
+static inline void vrange_lock(struct vrange_root *vroot)
+{
+	mutex_lock(&vroot->v_lock);
+}
+
+static inline void vrange_unlock(struct vrange_root *vroot)
+{
+	mutex_unlock(&vroot->v_lock);
+}
+
+static inline int vrange_type(struct vrange *vrange)
+{
+	return vrange->owner->type;
+}
+
+void vrange_init(void);
+extern void vrange_root_cleanup(struct vrange_root *vroot);
+
+#else
+
+static inline void vrange_init(void) {};
+static inline void vrange_root_init(struct vrange_root *vroot, int type) {};
+static inline void vrange_root_cleanup(struct vrange_root *vroot) {};
+
+#endif
+#endif /* _LINIUX_VRANGE_H */
diff --git a/include/linux/vrange_types.h b/include/linux/vrange_types.h
new file mode 100644
index 0000000..7f44c01
--- /dev/null
+++ b/include/linux/vrange_types.h
@@ -0,0 +1,19 @@
+#ifndef _LINUX_VRANGE_TYPES_H
+#define _LINUX_VRANGE_TYPES_H
+
+#include <linux/mutex.h>
+#include <linux/interval_tree.h>
+
+struct vrange_root {
+	struct rb_root v_rb;		/* vrange rb tree */
+	struct mutex v_lock;		/* Protect v_rb */
+	enum {VRANGE_MM, VRANGE_FILE} type; /* range root type */
+};
+
+struct vrange {
+	struct interval_tree_node node;
+	struct vrange_root *owner;
+	int purged;
+};
+#endif
+
diff --git a/init/main.c b/init/main.c
index 9484f4b..9cf08ba 100644
--- a/init/main.c
+++ b/init/main.c
@@ -74,6 +74,7 @@
 #include <linux/ptrace.h>
 #include <linux/blkdev.h>
 #include <linux/elevator.h>
+#include <linux/vrange.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -601,6 +602,7 @@ asmlinkage void __init start_kernel(void)
 	calibrate_delay();
 	pidmap_init();
 	anon_vma_init();
+	vrange_init();
 #ifdef CONFIG_X86
 	if (efi_enabled(EFI_RUNTIME_SERVICES))
 		efi_enter_virtual_mode();
diff --git a/lib/Makefile b/lib/Makefile
index c55a037..ccd15ff 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -13,7 +13,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
 	 proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
-	 earlycpio.o
+	 earlycpio.o interval_tree.o
 
 obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
 lib-$(CONFIG_MMU) += ioremap.o
diff --git a/mm/Makefile b/mm/Makefile
index 72c5acb..b67fcf5 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -5,7 +5,7 @@
 mmu-y			:= nommu.o
 mmu-$(CONFIG_MMU)	:= fremap.o highmem.o madvise.o memory.o mincore.o \
 			   mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
-			   vmalloc.o pagewalk.o pgtable-generic.o
+			   vmalloc.o pagewalk.o pgtable-generic.o vrange.o
 
 ifdef CONFIG_CROSS_MEMORY_ATTACH
 mmu-$(CONFIG_MMU)	+= process_vm_access.o
diff --git a/mm/vrange.c b/mm/vrange.c
new file mode 100644
index 0000000..e3042e0
--- /dev/null
+++ b/mm/vrange.c
@@ -0,0 +1,181 @@
+/*
+ * mm/vrange.c
+ */
+
+#include <linux/vrange.h>
+#include <linux/slab.h>
+
+static struct kmem_cache *vrange_cachep;
+
+void __init vrange_init(void)
+{
+	vrange_cachep = KMEM_CACHE(vrange, SLAB_PANIC);
+}
+
+static struct vrange *__vrange_alloc(gfp_t flags)
+{
+	struct vrange *vrange = kmem_cache_alloc(vrange_cachep, flags);
+	if (!vrange)
+		return vrange;
+	vrange->owner = NULL;
+	return vrange;
+}
+
+static void __vrange_free(struct vrange *range)
+{
+	WARN_ON(range->owner);
+	kmem_cache_free(vrange_cachep, range);
+}
+
+static void __vrange_add(struct vrange *range, struct vrange_root *vroot)
+{
+	range->owner = vroot;
+	interval_tree_insert(&range->node, &vroot->v_rb);
+}
+
+static void __vrange_remove(struct vrange *range)
+{
+	interval_tree_remove(&range->node, &range->owner->v_rb);
+	range->owner = NULL;
+}
+
+static inline void __vrange_set(struct vrange *range,
+		unsigned long start_idx, unsigned long end_idx,
+		bool purged)
+{
+	range->node.start = start_idx;
+	range->node.last = end_idx;
+	range->purged = purged;
+}
+
+static inline void __vrange_resize(struct vrange *range,
+		unsigned long start_idx, unsigned long end_idx)
+{
+	struct vrange_root *vroot = range->owner;
+	bool purged = range->purged;
+
+	__vrange_remove(range);
+	__vrange_set(range, start_idx, end_idx, purged);
+	__vrange_add(range, vroot);
+}
+
+static int vrange_add(struct vrange_root *vroot,
+			unsigned long start_idx, unsigned long end_idx)
+{
+	struct vrange *new_range, *range;
+	struct interval_tree_node *node, *next;
+	int purged = 0;
+
+	new_range = __vrange_alloc(GFP_KERNEL);
+	if (!new_range)
+		return -ENOMEM;
+
+	vrange_lock(vroot);
+
+	node = interval_tree_iter_first(&vroot->v_rb, start_idx, end_idx);
+	while (node) {
+		next = interval_tree_iter_next(node, start_idx, end_idx);
+		range = container_of(node, struct vrange, node);
+		/* old range covers new range fully */
+		if (node->start <= start_idx && node->last >= end_idx) {
+			__vrange_free(new_range);
+			goto out;
+		}
+
+		start_idx = min_t(unsigned long, start_idx, node->start);
+		end_idx = max_t(unsigned long, end_idx, node->last);
+		purged |= range->purged;
+
+		__vrange_remove(range);
+		__vrange_free(range);
+
+		node = next;
+	}
+
+	__vrange_set(new_range, start_idx, end_idx, purged);
+	__vrange_add(new_range, vroot);
+out:
+	vrange_unlock(vroot);
+	return 0;
+}
+
+static int vrange_remove(struct vrange_root *vroot,
+				unsigned long start_idx, unsigned long end_idx,
+				int *purged)
+{
+	struct vrange *new_range, *range;
+	struct interval_tree_node *node, *next;
+	bool used_new = false;
+
+	if (!purged)
+		return -EINVAL;
+
+	*purged = 0;
+
+	new_range = __vrange_alloc(GFP_KERNEL);
+	if (!new_range)
+		return -ENOMEM;
+
+	vrange_lock(vroot);
+
+	node = interval_tree_iter_first(&vroot->v_rb, start_idx, end_idx);
+	while (node) {
+		next = interval_tree_iter_next(node, start_idx, end_idx);
+		range = container_of(node, struct vrange, node);
+
+		*purged |= range->purged;
+
+		if (start_idx <= node->start && end_idx >= node->last) {
+			/* argumented range covers the range fully */
+			__vrange_remove(range);
+			__vrange_free(range);
+		} else if (node->start >= start_idx) {
+			/*
+			 * Argumented range covers over the left of the
+			 * range
+			 */
+			__vrange_resize(range, end_idx + 1, node->last);
+		} else if (node->last <= end_idx) {
+			/*
+			 * Argumented range covers over the right of the
+			 * range
+			 */
+			__vrange_resize(range, node->start, start_idx - 1);
+		} else {
+			/*
+			 * Argumented range is middle of the range
+			 */
+			used_new = true;
+			__vrange_resize(range, node->start, start_idx - 1);
+			__vrange_set(new_range, end_idx + 1, node->last,
+					range->purged);
+			__vrange_add(new_range, vroot);
+			break;
+		}
+
+		node = next;
+	}
+	vrange_unlock(vroot);
+
+	if (!used_new)
+		__vrange_free(new_range);
+
+	return 0;
+}
+
+void vrange_root_cleanup(struct vrange_root *vroot)
+{
+	struct vrange *range;
+	struct rb_node *next;
+
+	vrange_lock(vroot);
+	next = rb_first(&vroot->v_rb);
+	while (next) {
+		range = vrange_entry(next);
+		next = rb_next(next);
+		__vrange_remove(range);
+		__vrange_free(range);
+	}
+	vrange_unlock(vroot);
+}
+
-- 
1.8.1.2

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