Merge branch 'maint'

Conflicts:
	erts/preloaded/ebin/erlang.beam

1 files changed, 2832 insertions, 0 deletions

diff --git a/erts/emulator/sys/common/erl_mmap.c b/erts/emulator/sys/common/erl_mmap.c
new file mode 100644
index 0000000000..a9da7430fb
--- /dev/null
+++ b/erts/emulator/sys/common/erl_mmap.c
@@ -0,0 +1,2832 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2002-2013. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ *
+ * %CopyrightEnd%
+ */
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+#include "sys.h"
+#include "erl_process.h"
+#include "erl_smp.h"
+#include "atom.h"
+#include "erl_mmap.h"
+#include <stddef.h>
+
+/* #define ERTS_MMAP_OP_RINGBUF_SZ 100 */
+
+#if defined(DEBUG) || 0
+#  undef ERTS_MMAP_DEBUG
+#  define ERTS_MMAP_DEBUG
+#  ifndef ERTS_MMAP_OP_RINGBUF_SZ
+#    define ERTS_MMAP_OP_RINGBUF_SZ 100
+#  endif
+#endif
+
+#ifndef ERTS_MMAP_OP_RINGBUF_SZ
+#  define ERTS_MMAP_OP_RINGBUF_SZ 0
+#endif
+
+/* #define ERTS_MMAP_DEBUG_FILL_AREAS */
+
+#ifdef ERTS_MMAP_DEBUG
+#  define ERTS_MMAP_ASSERT ERTS_ASSERT
+#else
+#  define ERTS_MMAP_ASSERT(A) ((void) 1)
+#endif
+
+/*
+ * `mmap_state.sa.bot` and `mmap_state.sua.top` are read only after
+ * initialization, but the other pointers are not; i.e., only
+ * ERTS_MMAP_IN_SUPERCARRIER() is allowed without the mutex held.
+ */
+#define ERTS_MMAP_IN_SUPERCARRIER(PTR)					\
+    (((UWord) (PTR)) - ((UWord) mmap_state.sa.bot)			\
+     < ((UWord) mmap_state.sua.top) - ((UWord) mmap_state.sa.bot))
+#define ERTS_MMAP_IN_SUPERALIGNED_AREA(PTR)				\
+    (ERTS_SMP_LC_ASSERT(erts_lc_mtx_is_locked(&mmap_state.mtx)),	\
+     (((UWord) (PTR)) - ((UWord) mmap_state.sa.bot)			\
+      < ((UWord) mmap_state.sa.top) - ((UWord) mmap_state.sa.bot)))
+#define ERTS_MMAP_IN_SUPERUNALIGNED_AREA(PTR)				\
+    (ERTS_SMP_LC_ASSERT(erts_lc_mtx_is_locked(&mmap_state.mtx)),	\
+     (((UWord) (PTR)) - ((UWord) mmap_state.sua.bot)			\
+      < ((UWord) mmap_state.sua.top) - ((UWord) mmap_state.sua.bot)))
+
+int erts_have_erts_mmap;
+UWord erts_page_inv_mask;
+
+#if defined(DEBUG) || defined(ERTS_MMAP_DEBUG)
+#  undef RBT_DEBUG
+#  define RBT_DEBUG
+#endif
+#ifdef RBT_DEBUG
+#  define RBT_ASSERT	ERTS_ASSERT
+#  define IF_RBT_DEBUG(C) C
+#else
+#  define RBT_ASSERT(x)
+#  define IF_RBT_DEBUG(C)
+#endif
+
+typedef struct RBTNode_ RBTNode;
+struct RBTNode_ {
+    UWord parent_and_color;     /* color in bit 0 of parent ptr */
+    RBTNode *left;
+    RBTNode *right;
+};
+
+#define RED_FLG      (1)
+#define IS_RED(N)    ((N) && ((N)->parent_and_color & RED_FLG))
+#define IS_BLACK(N)  (!IS_RED(N))
+#define SET_RED(N)   ((N)->parent_and_color |= RED_FLG)
+#define SET_BLACK(N) ((N)->parent_and_color &= ~RED_FLG)
+
+static ERTS_INLINE RBTNode* parent(RBTNode* node)
+{
+    return (RBTNode*) (node->parent_and_color & ~RED_FLG);
+}
+
+static ERTS_INLINE void set_parent(RBTNode* node, RBTNode* parent)
+{
+    RBT_ASSERT(!((UWord)parent & RED_FLG));
+    node->parent_and_color = ((UWord)parent) | (node->parent_and_color & RED_FLG);
+}
+
+static ERTS_INLINE UWord parent_and_color(RBTNode* parent, int color)
+{
+    RBT_ASSERT(!((UWord)parent & RED_FLG));
+    RBT_ASSERT(!(color & ~RED_FLG));
+    return ((UWord)parent) | color;
+}
+
+
+enum SortOrder {
+    ADDR_ORDER,             /* only address order */
+    SA_SZ_ADDR_ORDER,        /* first super-aligned size then address order */
+    SZ_REVERSE_ADDR_ORDER   /* first size then reverse address order */
+};
+#ifdef HARD_DEBUG
+static const char* sort_order_names[] = {"Address","SuperAlignedSize-Address","Size-RevAddress"};
+#endif
+
+typedef struct {
+    RBTNode* root;
+    enum SortOrder order;
+}RBTree;
+
+#ifdef HARD_DEBUG
+#  define HARD_CHECK_IS_MEMBER(ROOT,NODE) rbt_assert_is_member(ROOT,NODE)
+#  define HARD_CHECK_TREE(TREE,SZ) check_tree(TREE, SZ)
+static int rbt_assert_is_member(RBTNode* root, RBTNode* node);
+static RBTNode* check_tree(RBTree* tree, Uint);
+#else
+#  define HARD_CHECK_IS_MEMBER(ROOT,NODE)
+#  define HARD_CHECK_TREE(TREE,SZ)
+#endif
+
+#if ERTS_MMAP_OP_RINGBUF_SZ
+
+static int mmap_op_ix;
+
+typedef enum {
+    ERTS_OP_TYPE_NONE,
+    ERTS_OP_TYPE_MMAP,
+    ERTS_OP_TYPE_MUNMAP,
+    ERTS_OP_TYPE_MREMAP
+} ErtsMMapOpType;
+
+typedef struct {
+    ErtsMMapOpType type;
+    void *result;
+    UWord in_size;
+    UWord out_size;
+    void *old_ptr;
+    UWord old_size;
+} ErtsMMapOp;
+
+static ErtsMMapOp mmap_ops[ERTS_MMAP_OP_RINGBUF_SZ];
+
+#define ERTS_MMAP_OP_RINGBUF_INIT()				\
+    do {							\
+	int ix__;						\
+	for (ix__ = 0; ix__ < ERTS_MMAP_OP_RINGBUF_SZ; ix__++) {\
+	    mmap_ops[ix__].type = ERTS_OP_TYPE_NONE;		\
+	    mmap_ops[ix__].result = NULL;			\
+	    mmap_ops[ix__].in_size = 0;				\
+	    mmap_ops[ix__].out_size = 0;			\
+	    mmap_ops[ix__].old_ptr = NULL;			\
+	    mmap_ops[ix__].old_size = 0;			\
+	}							\
+	mmap_op_ix = ERTS_MMAP_OP_RINGBUF_SZ-1;			\
+    } while (0)
+
+#define ERTS_MMAP_OP_START(SZ) 					\
+    do {							\
+	int ix__;						\
+	if (++mmap_op_ix >= ERTS_MMAP_OP_RINGBUF_SZ)		\
+	    mmap_op_ix = 0;					\
+	ix__ = mmap_op_ix;					\
+	mmap_ops[ix__].type = ERTS_OP_TYPE_MMAP;		\
+	mmap_ops[ix__].result = NULL;				\
+	mmap_ops[ix__].in_size = (SZ);				\
+	mmap_ops[ix__].out_size = 0;				\
+	mmap_ops[ix__].old_ptr = NULL;				\
+	mmap_ops[ix__].old_size = 0;				\
+    } while (0)
+
+#define ERTS_MMAP_OP_END(PTR, SZ)				\
+    do {							\
+	int ix__ = mmap_op_ix;					\
+	mmap_ops[ix__].result = (PTR);				\
+	mmap_ops[ix__].out_size = (SZ);				\
+    } while (0)
+
+#define ERTS_MMAP_OP_LCK(RES, IN_SZ, OUT_SZ)			\
+    do {							\
+	erts_smp_mtx_lock(&mmap_state.mtx);			\
+	ERTS_MMAP_OP_START((IN_SZ));				\
+	ERTS_MMAP_OP_END((RES), (OUT_SZ));			\
+	erts_smp_mtx_unlock(&mmap_state.mtx);			\
+    } while (0)
+
+#define ERTS_MUNMAP_OP(PTR, SZ)					\
+    do {							\
+	int ix__;						\
+	if (++mmap_op_ix >= ERTS_MMAP_OP_RINGBUF_SZ)		\
+	    mmap_op_ix = 0;					\
+	ix__ = mmap_op_ix;					\
+	mmap_ops[ix__].type = ERTS_OP_TYPE_MUNMAP;		\
+	mmap_ops[ix__].result = NULL;				\
+	mmap_ops[ix__].in_size = 0;				\
+	mmap_ops[ix__].out_size = 0;				\
+	mmap_ops[ix__].old_ptr = (PTR);				\
+	mmap_ops[ix__].old_size = (SZ);				\
+    } while (0)
+
+#define ERTS_MUNMAP_OP_LCK(PTR, SZ)				\
+    do {							\
+	erts_smp_mtx_lock(&mmap_state.mtx);			\
+	ERTS_MUNMAP_OP((PTR), (SZ));				\
+	erts_smp_mtx_unlock(&mmap_state.mtx);			\
+    } while (0)
+
+#define ERTS_MREMAP_OP_START(OLD_PTR, OLD_SZ, IN_SZ)		\
+    do {							\
+	int ix__;						\
+	if (++mmap_op_ix >= ERTS_MMAP_OP_RINGBUF_SZ)		\
+	    mmap_op_ix = 0;					\
+	ix__ = mmap_op_ix;					\
+	mmap_ops[ix__].type = ERTS_OP_TYPE_MREMAP;		\
+	mmap_ops[ix__].result = NULL;				\
+	mmap_ops[ix__].in_size = (IN_SZ);			\
+	mmap_ops[ix__].out_size = (OLD_SZ);			\
+	mmap_ops[ix__].old_ptr = (OLD_PTR);			\
+	mmap_ops[ix__].old_size = (OLD_SZ);			\
+    } while (0)
+
+#define ERTS_MREMAP_OP_END(PTR, SZ)				\
+    do {							\
+	int ix__ = mmap_op_ix;					\
+	mmap_ops[ix__].result = (PTR);				\
+	mmap_ops[mmap_op_ix].out_size = (SZ);			\
+    } while (0)
+
+#define ERTS_MREMAP_OP_LCK(RES, OLD_PTR, OLD_SZ, IN_SZ, OUT_SZ)	\
+    do {							\
+	erts_smp_mtx_lock(&mmap_state.mtx);			\
+	ERTS_MREMAP_OP_START((OLD_PTR), (OLD_SZ), (IN_SZ));	\
+	ERTS_MREMAP_OP_END((RES), (OUT_SZ));			\
+	erts_smp_mtx_unlock(&mmap_state.mtx);			\
+    } while (0)
+
+#define ERTS_MMAP_OP_ABORT()					\
+    do {							\
+	int ix__ = mmap_op_ix;					\
+	mmap_ops[ix__].type = ERTS_OP_TYPE_NONE;		\
+	mmap_ops[ix__].result = NULL;				\
+	mmap_ops[ix__].in_size = 0;				\
+	mmap_ops[ix__].out_size = 0;				\
+	mmap_ops[ix__].old_ptr = NULL;				\
+	mmap_ops[ix__].old_size = 0;				\
+	if (--mmap_op_ix < 0)					\
+	    mmap_op_ix = ERTS_MMAP_OP_RINGBUF_SZ-1;		\
+    } while (0)
+
+#else
+
+#define ERTS_MMAP_OP_RINGBUF_INIT()
+#define ERTS_MMAP_OP_START(SZ)
+#define ERTS_MMAP_OP_END(PTR, SZ)
+#define ERTS_MMAP_OP_LCK(RES, IN_SZ, OUT_SZ)
+#define ERTS_MUNMAP_OP(PTR, SZ)
+#define ERTS_MUNMAP_OP_LCK(PTR, SZ)
+#define ERTS_MREMAP_OP_START(OLD_PTR, OLD_SZ, IN_SZ)
+#define ERTS_MREMAP_OP_END(PTR, SZ)
+#define ERTS_MREMAP_OP_LCK(RES, OLD_PTR, OLD_SZ, IN_SZ, OUT_SZ)
+#define ERTS_MMAP_OP_ABORT()
+
+#endif
+
+typedef struct {
+    RBTNode snode;      /* node in 'stree' */
+    RBTNode anode;      /* node in 'atree' */
+    char* start;
+    char* end;
+}ErtsFreeSegDesc;
+
+typedef struct {
+    RBTree stree;       /* size ordered tree */
+    RBTree atree;       /* address ordered tree */
+    Uint nseg;
+}ErtsFreeSegMap;
+
+static struct {
+    int (*reserve_physical)(char *, UWord);
+    void (*unreserve_physical)(char *, UWord);
+    int supercarrier;
+    int no_os_mmap;
+    /*
+     * Super unaligend area is located above super aligned
+     * area. That is, `sa.bot` is beginning of the super
+     * carrier, `sua.top` is the end of the super carrier,
+     * and sa.top and sua.bot moves towards eachother.
+     */
+    struct {
+	char *top;
+	char *bot;
+	ErtsFreeSegMap map;
+    } sua;
+    struct {
+	char *top;
+	char *bot;
+	ErtsFreeSegMap map;
+    } sa;
+#if HAVE_MMAP && (!defined(MAP_ANON) && !defined(MAP_ANONYMOUS))
+    int mmap_fd;
+#endif
+    erts_smp_mtx_t mtx;
+    struct {
+	char *free_list;
+	char *unused_start;
+	char *unused_end;
+	char *new_area_hint;
+        Uint reserved;
+    } desc;
+    struct {
+	UWord free_seg_descs;
+	struct {
+	    UWord curr;
+	    UWord max;
+	} free_segs;
+    } no;
+    struct {
+	struct {
+	    UWord total;
+	    struct {
+		UWord total;
+		UWord sa;
+		UWord sua;
+	    } used;
+	} supercarrier;
+	struct {
+	    UWord used;
+	} os;
+    } size;
+} mmap_state;
+
+#define ERTS_MMAP_SIZE_SC_SA_INC(SZ) 						\
+    do {									\
+	mmap_state.size.supercarrier.used.total += (SZ);			\
+	mmap_state.size.supercarrier.used.sa += (SZ);				\
+	ERTS_MMAP_ASSERT(mmap_state.size.supercarrier.used.total		\
+			 <= mmap_state.size.supercarrier.total);		\
+	ERTS_MMAP_ASSERT(mmap_state.size.supercarrier.used.sa			\
+			 <= mmap_state.size.supercarrier.used.total);		\
+    } while (0)
+#define ERTS_MMAP_SIZE_SC_SA_DEC(SZ) 						\
+    do {									\
+	ERTS_MMAP_ASSERT(mmap_state.size.supercarrier.used.total >= (SZ));	\
+	mmap_state.size.supercarrier.used.total -= (SZ);			\
+	ERTS_MMAP_ASSERT(mmap_state.size.supercarrier.used.sa >= (SZ));		\
+	mmap_state.size.supercarrier.used.sa -= (SZ);				\
+    } while (0)
+#define ERTS_MMAP_SIZE_SC_SUA_INC(SZ) 						\
+    do {									\
+	mmap_state.size.supercarrier.used.total += (SZ);			\
+	mmap_state.size.supercarrier.used.sua += (SZ);				\
+	ERTS_MMAP_ASSERT(mmap_state.size.supercarrier.used.total		\
+			 <= mmap_state.size.supercarrier.total);		\
+	ERTS_MMAP_ASSERT(mmap_state.size.supercarrier.used.sua			\
+			 <= mmap_state.size.supercarrier.used.total);		\
+    } while (0)
+#define ERTS_MMAP_SIZE_SC_SUA_DEC(SZ) 						\
+    do {									\
+	ERTS_MMAP_ASSERT(mmap_state.size.supercarrier.used.total >= (SZ));	\
+	mmap_state.size.supercarrier.used.total -= (SZ);			\
+	ERTS_MMAP_ASSERT(mmap_state.size.supercarrier.used.sua >= (SZ));	\
+	mmap_state.size.supercarrier.used.sua -= (SZ);				\
+    } while (0)
+#define ERTS_MMAP_SIZE_OS_INC(SZ)						\
+    do {									\
+	ERTS_MMAP_ASSERT(mmap_state.size.os.used + (SZ) >= (SZ));		\
+	mmap_state.size.os.used += (SZ);					\
+    } while (0)
+#define ERTS_MMAP_SIZE_OS_DEC(SZ) 						\
+    do {									\
+	ERTS_MMAP_ASSERT(mmap_state.size.os.used >= (SZ));			\
+	mmap_state.size.os.used -= (SZ);					\
+    } while (0)
+
+
+static void
+add_free_desc_area(char *start, char *end)
+{
+    ERTS_MMAP_ASSERT(end == (void *) 0 || end > start);
+    if (sizeof(ErtsFreeSegDesc) <= ((UWord) end) - ((UWord) start)) {
+	UWord no;
+	ErtsFreeSegDesc *prev_desc, *desc;
+	char *desc_end;
+
+	no = 1;
+	prev_desc = (ErtsFreeSegDesc *) start;
+	prev_desc->start = mmap_state.desc.free_list;
+	desc = (ErtsFreeSegDesc *) (start + sizeof(ErtsFreeSegDesc));
+	desc_end = start + 2*sizeof(ErtsFreeSegDesc);
+
+	while (desc_end <= end) {
+	    desc->start = (char *) prev_desc;
+	    prev_desc = desc;
+	    desc = (ErtsFreeSegDesc *) desc_end;
+	    desc_end += sizeof(ErtsFreeSegDesc);
+	    no++;
+	}
+	mmap_state.desc.free_list = (char *) prev_desc;
+	mmap_state.no.free_seg_descs += no;
+    }
+}
+
+static ErtsFreeSegDesc *
+add_unused_free_desc_area(void)
+{
+    char *ptr;
+    if (!mmap_state.desc.unused_start)
+	return NULL;
+
+    ERTS_MMAP_ASSERT(mmap_state.desc.unused_end);
+    ERTS_MMAP_ASSERT(ERTS_PAGEALIGNED_SIZE
+		     <= mmap_state.desc.unused_end - mmap_state.desc.unused_start);
+
+    ptr = mmap_state.desc.unused_start + ERTS_PAGEALIGNED_SIZE;
+    add_free_desc_area(mmap_state.desc.unused_start, ptr);
+
+    if ((mmap_state.desc.unused_end - ptr) >= ERTS_PAGEALIGNED_SIZE)
+	mmap_state.desc.unused_start = ptr;
+    else
+	mmap_state.desc.unused_end = mmap_state.desc.unused_start = NULL;
+
+    ERTS_MMAP_ASSERT(mmap_state.desc.free_list);
+    return (ErtsFreeSegDesc *) mmap_state.desc.free_list;
+}
+
+static ERTS_INLINE ErtsFreeSegDesc *
+alloc_desc(void)
+{
+    ErtsFreeSegDesc *res;
+    res = (ErtsFreeSegDesc *) mmap_state.desc.free_list;
+    if (!res) {
+	res = add_unused_free_desc_area();
+	if (!res)
+	    return NULL;
+    }
+    mmap_state.desc.free_list = res->start;
+    ASSERT(mmap_state.no.free_segs.curr < mmap_state.no.free_seg_descs);
+    mmap_state.no.free_segs.curr++;
+    if (mmap_state.no.free_segs.max < mmap_state.no.free_segs.curr)
+	mmap_state.no.free_segs.max = mmap_state.no.free_segs.curr;
+    return res;
+}
+
+static ERTS_INLINE void
+free_desc(ErtsFreeSegDesc *desc)
+{
+    desc->start = mmap_state.desc.free_list;
+    mmap_state.desc.free_list = (char *) desc;
+    ERTS_MMAP_ASSERT(mmap_state.no.free_segs.curr > 0);
+    mmap_state.no.free_segs.curr--;
+}
+
+static ERTS_INLINE ErtsFreeSegDesc* anode_to_desc(RBTNode* anode)
+{
+    return (ErtsFreeSegDesc*) ((char*)anode - offsetof(ErtsFreeSegDesc, anode));
+}
+
+static ERTS_INLINE ErtsFreeSegDesc* snode_to_desc(RBTNode* snode)
+{
+    return (ErtsFreeSegDesc*) ((char*)snode - offsetof(ErtsFreeSegDesc, snode));
+}
+
+static ERTS_INLINE ErtsFreeSegDesc* node_to_desc(enum SortOrder order, RBTNode* node)
+{
+    return order==ADDR_ORDER ? anode_to_desc(node) : snode_to_desc(node);
+}
+
+static ERTS_INLINE SWord usable_size(enum SortOrder order,
+                                     ErtsFreeSegDesc* desc)
+{
+    return ((order == SA_SZ_ADDR_ORDER) ?
+            ERTS_SUPERALIGNED_FLOOR(desc->end) - ERTS_SUPERALIGNED_CEILING(desc->start)
+            : desc->end - desc->start);
+}
+
+#ifdef HARD_DEBUG
+static ERTS_INLINE SWord cmp_nodes(enum SortOrder order,
+                                   RBTNode* lhs, RBTNode* rhs)
+{
+    ErtsFreeSegDesc* ldesc = node_to_desc(order, lhs);
+    ErtsFreeSegDesc* rdesc = node_to_desc(order, rhs);
+    RBT_ASSERT(lhs != rhs);
+    if (order != ADDR_ORDER) {
+        SWord diff = usable_size(order, ldesc) - usable_size(order, rdesc);
+	if (diff) return diff;
+    }
+    if (order != SZ_REVERSE_ADDR_ORDER) {
+        return (char*)ldesc->start - (char*)rdesc->start;
+    }
+    else {
+        return (char*)rdesc->start - (char*)ldesc->start;
+    }
+}
+#endif  /* HARD_DEBUG */
+
+static ERTS_INLINE SWord cmp_with_node(enum SortOrder order,
+                                       SWord sz, char* addr, RBTNode* rhs)
+{
+    ErtsFreeSegDesc* rdesc;
+    if (order != ADDR_ORDER) {
+        SWord diff;
+        rdesc = snode_to_desc(rhs);
+        diff = sz - usable_size(order, rdesc);
+        if (diff) return diff;
+    }
+    else
+        rdesc = anode_to_desc(rhs);
+
+    if (order != SZ_REVERSE_ADDR_ORDER)
+        return addr - (char*)rdesc->start;
+    else
+        return (char*)rdesc->start - addr;
+}
+
+
+static ERTS_INLINE void
+left_rotate(RBTNode **root, RBTNode *x)
+{
+    RBTNode *y = x->right;
+    x->right = y->left;
+    if (y->left)
+	set_parent(y->left, x);
+    set_parent(y, parent(x));
+    if (!parent(y)) {
+	RBT_ASSERT(*root == x);
+	*root = y;
+    }
+    else if (x == parent(x)->left)
+	parent(x)->left = y;
+    else {
+	RBT_ASSERT(x == parent(x)->right);
+	parent(x)->right = y;
+    }
+    y->left = x;
+    set_parent(x, y);
+}
+
+static ERTS_INLINE void
+right_rotate(RBTNode **root, RBTNode *x)
+{
+    RBTNode *y = x->left;
+    x->left = y->right;
+    if (y->right)
+	set_parent(y->right, x);
+    set_parent(y, parent(x));
+    if (!parent(y)) {
+	RBT_ASSERT(*root == x);
+	*root = y;
+    }
+    else if (x == parent(x)->right)
+	parent(x)->right = y;
+    else {
+	RBT_ASSERT(x == parent(x)->left);
+	parent(x)->left = y;
+    }
+    y->right = x;
+    set_parent(x, y);
+}
+
+/*
+ * Replace node x with node y
+ * NOTE: segment descriptor of y is not changed
+ */
+static ERTS_INLINE void
+replace(RBTNode **root, RBTNode *x, RBTNode *y)
+{
+
+    if (!parent(x)) {
+	RBT_ASSERT(*root == x);
+	*root = y;
+    }
+    else if (x == parent(x)->left)
+	parent(x)->left = y;
+    else {
+	RBT_ASSERT(x == parent(x)->right);
+	parent(x)->right = y;
+    }
+    if (x->left) {
+	RBT_ASSERT(parent(x->left) == x);
+	set_parent(x->left, y);
+    }
+    if (x->right) {
+	RBT_ASSERT(parent(x->right) == x);
+	set_parent(x->right, y);
+    }
+
+    y->parent_and_color	= x->parent_and_color;
+    y->right	= x->right;
+    y->left	= x->left;
+}
+
+static void
+tree_insert_fixup(RBTNode** root, RBTNode *node)
+{
+    RBTNode *x = node, *y, *papa_x, *granpa_x;
+
+    /*
+     * Rearrange the tree so that it satisfies the Red-Black Tree properties
+     */
+
+    papa_x = parent(x);
+    RBT_ASSERT(x != *root && IS_RED(papa_x));
+    do {
+
+	/*
+	 * x and its parent are both red. Move the red pair up the tree
+	 * until we get to the root or until we can separate them.
+	 */
+
+        granpa_x = parent(papa_x);
+	RBT_ASSERT(IS_RED(x));
+	RBT_ASSERT(IS_BLACK(granpa_x));
+	RBT_ASSERT(granpa_x);
+
+	if (papa_x == granpa_x->left) {
+	    y = granpa_x->right;
+	    if (IS_RED(y)) {
+		SET_BLACK(y);
+		SET_BLACK(papa_x);
+		SET_RED(granpa_x);
+                x = granpa_x;
+	    }
+	    else {
+
+		if (x == papa_x->right) {
+		    left_rotate(root, papa_x);
+                    papa_x = x;
+                    x = papa_x->left;
+		}
+
+		RBT_ASSERT(x == granpa_x->left->left);
+		RBT_ASSERT(IS_RED(x));
+		RBT_ASSERT(IS_RED(papa_x));
+		RBT_ASSERT(IS_BLACK(granpa_x));
+		RBT_ASSERT(IS_BLACK(y));
+
+		SET_BLACK(papa_x);
+		SET_RED(granpa_x);
+		right_rotate(root, granpa_x);
+
+		RBT_ASSERT(x == parent(x)->left);
+		RBT_ASSERT(IS_RED(x));
+		RBT_ASSERT(IS_RED(parent(x)->right));
+		RBT_ASSERT(IS_BLACK(parent(x)));
+		break;
+	    }
+	}
+	else {
+	    RBT_ASSERT(papa_x == granpa_x->right);
+	    y = granpa_x->left;
+	    if (IS_RED(y)) {
+		SET_BLACK(y);
+		SET_BLACK(papa_x);
+		SET_RED(granpa_x);
+                x = granpa_x;
+	    }
+	    else {
+
+		if (x == papa_x->left) {
+		    right_rotate(root, papa_x);
+                    papa_x = x;
+                    x = papa_x->right;
+		}
+
+		RBT_ASSERT(x == granpa_x->right->right);
+		RBT_ASSERT(IS_RED(x));
+		RBT_ASSERT(IS_RED(papa_x));
+		RBT_ASSERT(IS_BLACK(granpa_x));
+		RBT_ASSERT(IS_BLACK(y));
+
+		SET_BLACK(papa_x);
+		SET_RED(granpa_x);
+		left_rotate(root, granpa_x);
+
+		RBT_ASSERT(x == parent(x)->right);
+		RBT_ASSERT(IS_RED(x));
+		RBT_ASSERT(IS_RED(parent(x)->left));
+		RBT_ASSERT(IS_BLACK(parent(x)));
+		break;
+	    }
+	}
+    } while (x != *root && (papa_x=parent(x), IS_RED(papa_x)));
+
+    SET_BLACK(*root);
+}
+
+static void
+rbt_delete(RBTree* tree, RBTNode* del)
+{
+    Uint spliced_is_black;
+    RBTNode *x, *y, *z = del, *papa_y;
+    RBTNode null_x; /* null_x is used to get the fixup started when we
+			splice out a node without children. */
+
+    HARD_CHECK_IS_MEMBER(tree->root, del);
+    HARD_CHECK_TREE(tree, 0);
+
+    null_x.parent_and_color = parent_and_color(NULL, !RED_FLG);
+
+    /* Remove node from tree... */
+
+    /* Find node to splice out */
+    if (!z->left || !z->right)
+	y = z;
+    else
+	/* Set y to z:s successor */
+	for(y = z->right; y->left; y = y->left);
+    /* splice out y */
+    x = y->left ? y->left : y->right;
+    spliced_is_black = IS_BLACK(y);
+    papa_y = parent(y);
+    if (x) {
+	set_parent(x, papa_y);
+    }
+    else if (spliced_is_black) {
+	x = &null_x;
+	x->right = x->left = NULL;
+	x->parent_and_color = parent_and_color(papa_y, !RED_FLG);
+	y->left = x;
+    }
+
+    if (!papa_y) {
+	RBT_ASSERT(tree->root == y);
+	tree->root = x;
+    }
+    else {
+	if (y == papa_y->left) {
+	    papa_y->left = x;
+	}
+	else {
+	    RBT_ASSERT(y == papa_y->right);
+	    papa_y->right = x;
+	}
+    }
+    if (y != z) {
+	/* We spliced out the successor of z; replace z by the successor */
+	RBT_ASSERT(z != &null_x);
+	replace(&tree->root, z, y);
+    }
+
+    if (spliced_is_black) {
+        RBTNode* papa_x;
+	/* We removed a black node which makes the resulting tree
+	   violate the Red-Black Tree properties. Fixup tree... */
+
+        papa_x = parent(x);
+	while (IS_BLACK(x) && papa_x) {
+
+	    /*
+	     * x has an "extra black" which we move up the tree
+	     * until we reach the root or until we can get rid of it.
+	     *
+	     * y is the sibbling of x
+	     */
+
+	    if (x == papa_x->left) {
+		y = papa_x->right;
+		RBT_ASSERT(y);
+		if (IS_RED(y)) {
+		    RBT_ASSERT(y->right);
+		    RBT_ASSERT(y->left);
+		    SET_BLACK(y);
+		    RBT_ASSERT(IS_BLACK(papa_x));
+		    SET_RED(papa_x);
+		    left_rotate(&tree->root, papa_x);
+                    RBT_ASSERT(papa_x == parent(x));
+		    y = papa_x->right;
+		}
+		RBT_ASSERT(y);
+		RBT_ASSERT(IS_BLACK(y));
+		if (IS_BLACK(y->left) && IS_BLACK(y->right)) {
+		    SET_RED(y);
+		}
+		else {
+		    if (IS_BLACK(y->right)) {
+			SET_BLACK(y->left);
+			SET_RED(y);
+			right_rotate(&tree->root, y);
+                        RBT_ASSERT(papa_x == parent(x));
+			y = papa_x->right;
+		    }
+		    RBT_ASSERT(y);
+		    if (IS_RED(papa_x)) {
+
+			SET_BLACK(papa_x);
+			SET_RED(y);
+		    }
+		    RBT_ASSERT(y->right);
+		    SET_BLACK(y->right);
+		    left_rotate(&tree->root, papa_x);
+		    x = tree->root;
+		    break;
+		}
+	    }
+	    else {
+		RBT_ASSERT(x == papa_x->right);
+		y = papa_x->left;
+		RBT_ASSERT(y);
+		if (IS_RED(y)) {
+		    RBT_ASSERT(y->right);
+		    RBT_ASSERT(y->left);
+		    SET_BLACK(y);
+		    RBT_ASSERT(IS_BLACK(papa_x));
+		    SET_RED(papa_x);
+		    right_rotate(&tree->root, papa_x);
+                    RBT_ASSERT(papa_x == parent(x));
+		    y = papa_x->left;
+		}
+		RBT_ASSERT(y);
+		RBT_ASSERT(IS_BLACK(y));
+		if (IS_BLACK(y->right) && IS_BLACK(y->left)) {
+		    SET_RED(y);
+		}
+		else {
+		    if (IS_BLACK(y->left)) {
+			SET_BLACK(y->right);
+			SET_RED(y);
+			left_rotate(&tree->root, y);
+                        RBT_ASSERT(papa_x == parent(x));
+			y = papa_x->left;
+		    }
+		    RBT_ASSERT(y);
+		    if (IS_RED(papa_x)) {
+			SET_BLACK(papa_x);
+			SET_RED(y);
+		    }
+		    RBT_ASSERT(y->left);
+		    SET_BLACK(y->left);
+		    right_rotate(&tree->root, papa_x);
+		    x = tree->root;
+		    break;
+		}
+	    }
+            x = papa_x;
+            papa_x = parent(x);
+	}
+	SET_BLACK(x);
+
+        papa_x = parent(&null_x);
+	if (papa_x) {
+	    if (papa_x->left == &null_x)
+		papa_x->left = NULL;
+	    else {
+		RBT_ASSERT(papa_x->right == &null_x);
+		papa_x->right = NULL;
+	    }
+	    RBT_ASSERT(!null_x.left);
+	    RBT_ASSERT(!null_x.right);
+	}
+	else if (tree->root == &null_x) {
+	    tree->root = NULL;
+	    RBT_ASSERT(!null_x.left);
+	    RBT_ASSERT(!null_x.right);
+	}
+    }
+    HARD_CHECK_TREE(tree, 0);
+}
+
+
+static void
+rbt_insert(RBTree* tree, RBTNode* node)
+{
+#ifdef RBT_DEBUG
+    ErtsFreeSegDesc *dbg_under=NULL, *dbg_over=NULL;
+#endif
+    ErtsFreeSegDesc* desc = node_to_desc(tree->order, node);
+    char* seg_addr = desc->start;
+    SWord seg_sz = desc->end - desc->start;
+
+    HARD_CHECK_TREE(tree, 0);
+
+    node->left	= NULL;
+    node->right	= NULL;
+
+    if (!tree->root) {
+	node->parent_and_color = parent_and_color(NULL, !RED_FLG);
+	tree->root = node;
+    }
+    else {
+	RBTNode *x = tree->root;
+	while (1) {
+	    SWord diff = cmp_with_node(tree->order, seg_sz, seg_addr, x);
+	    if (diff < 0) {
+                IF_RBT_DEBUG(dbg_over = node_to_desc(tree->order, x));
+		if (!x->left) {
+		    node->parent_and_color = parent_and_color(x, RED_FLG);
+		    x->left = node;
+		    break;
+		}
+		x = x->left;
+	    }
+	    else {
+                RBT_ASSERT(diff > 0);
+                IF_RBT_DEBUG(dbg_under = node_to_desc(tree->order, x));
+                if (!x->right) {
+                    node->parent_and_color = parent_and_color(x, RED_FLG);
+                    x->right = node;
+                    break;
+                }
+                x = x->right;
+            }
+	}
+
+	RBT_ASSERT(parent(node));
+#ifdef RBT_DEBUG
+        if (tree->order == ADDR_ORDER) {
+            RBT_ASSERT(!dbg_under || dbg_under->end < desc->start);
+            RBT_ASSERT(!dbg_over || dbg_over->start > desc->end);
+        }
+#endif
+        RBT_ASSERT(IS_RED(node));
+	if (IS_RED(parent(node)))
+	    tree_insert_fixup(&tree->root, node);
+    }
+    HARD_CHECK_TREE(tree, 0);
+}
+
+/*
+ * Traverse tree in (reverse) sorting order
+ */
+static void
+rbt_foreach_node(RBTree* tree,
+                 void (*fn)(RBTNode*,void*),
+                 void* arg, int reverse)
+{
+#ifdef HARD_DEBUG
+    Sint blacks = -1;
+    Sint curr_blacks = 1;
+    Uint depth = 1;
+    Uint max_depth = 0;
+    Uint node_cnt = 0;
+#endif
+    enum { RECURSE_LEFT, DO_NODE, RECURSE_RIGHT, RETURN_TO_PARENT }state;
+    RBTNode *x = tree->root;
+
+    RBT_ASSERT(!x || !parent(x));
+
+    state = reverse ? RECURSE_RIGHT : RECURSE_LEFT;
+    while (x) {
+        switch (state) {
+        case RECURSE_LEFT:
+            if (x->left) {
+                RBT_ASSERT(parent(x->left) == x);
+              #ifdef HARD_DEBUG
+                ++depth;
+                if (IS_BLACK(x->left))
+                    curr_blacks++;
+              #endif
+                x = x->left;
+                state = reverse ? RECURSE_RIGHT : RECURSE_LEFT;
+            }
+            else {
+              #ifdef HARD_DEBUG
+                if (blacks < 0)
+                    blacks = curr_blacks;
+                RBT_ASSERT(blacks == curr_blacks);
+              #endif
+                state = reverse ? RETURN_TO_PARENT : DO_NODE;
+            }
+            break;
+
+        case DO_NODE:
+          #ifdef HARD_DEBUG
+            ++node_cnt;
+            if (depth > max_depth)
+                max_depth = depth;
+          #endif
+            (*fn) (x, arg); /* Do it! */
+            state = reverse ? RECURSE_LEFT : RECURSE_RIGHT;
+            break;
+
+        case RECURSE_RIGHT:
+            if (x->right) {
+                RBT_ASSERT(parent(x->right) == x);
+              #ifdef HARD_DEBUG
+                ++depth;
+                if (IS_BLACK(x->right))
+                    curr_blacks++;
+              #endif
+                x = x->right;
+                state = reverse ? RECURSE_RIGHT : RECURSE_LEFT;
+            }
+            else {
+              #ifdef HARD_DEBUG
+                if (blacks < 0)
+                    blacks = curr_blacks;
+                RBT_ASSERT(blacks == curr_blacks);
+              #endif
+                state = reverse ? DO_NODE : RETURN_TO_PARENT;
+            }
+            break;
+
+        case RETURN_TO_PARENT:
+          #ifdef HARD_DEBUG
+            if (IS_BLACK(x))
+                curr_blacks--;
+            --depth;
+          #endif
+            if (parent(x)) {
+                if (x == parent(x)->left) {
+                    state = reverse ? RETURN_TO_PARENT : DO_NODE;
+                }
+                else {
+                    RBT_ASSERT(x == parent(x)->right);
+                    state = reverse ? DO_NODE : RETURN_TO_PARENT;
+                }
+            }
+            x = parent(x);
+            break;
+        }
+    }
+#ifdef HARD_DEBUG
+    RBT_ASSERT(depth == 0 || (!tree->root && depth==1));
+    RBT_ASSERT(curr_blacks == 0);
+    RBT_ASSERT((1 << (max_depth/2)) <= node_cnt);
+#endif
+}
+
+#if defined(RBT_DEBUG) || defined(HARD_DEBUG_MSEG)
+static RBTNode* rbt_prev_node(RBTNode* node)
+{
+    RBTNode* x;
+    if (node->left) {
+        for (x=node->left; x->right; x=x->right)
+            ;
+        return x;
+    }
+    for (x=node; parent(x); x=parent(x)) {
+        if (parent(x)->right == x)
+            return parent(x);
+    }
+    return NULL;
+}
+static RBTNode* rbt_next_node(RBTNode* node)
+{
+    RBTNode* x;
+    if (node->right) {
+        for (x=node->right; x->left; x=x->left)
+            ;
+        return x;
+    }
+    for (x=node; parent(x); x=parent(x)) {
+        if (parent(x)->left == x)
+            return parent(x);
+    }
+    return NULL;
+}
+#endif /* RBT_DEBUG || HARD_DEBUG_MSEG */
+
+
+/* The API to keep track of a bunch of separated (free) segments
+   (non-overlapping and non-adjacent).
+ */
+static void init_free_seg_map(ErtsFreeSegMap*, enum SortOrder);
+static void adjacent_free_seg(ErtsFreeSegMap*, char* start, char* end,
+                              ErtsFreeSegDesc** under, ErtsFreeSegDesc** over);
+static void insert_free_seg(ErtsFreeSegMap*, ErtsFreeSegDesc*, char* start, char* end);
+static void resize_free_seg(ErtsFreeSegMap*, ErtsFreeSegDesc*, char* start, char* end);
+static void delete_free_seg(ErtsFreeSegMap*, ErtsFreeSegDesc*);
+static ErtsFreeSegDesc* lookup_free_seg(ErtsFreeSegMap*, SWord sz);
+
+
+static void init_free_seg_map(ErtsFreeSegMap* map, enum SortOrder order)
+{
+    map->atree.root = NULL;
+    map->atree.order = ADDR_ORDER;
+    map->stree.root = NULL;
+    map->stree.order = order;
+    map->nseg = 0;
+}
+
+/* Lookup directly adjacent free segments to the given area [start->end].
+ * The given area must not contain any free segments.
+ */
+static void adjacent_free_seg(ErtsFreeSegMap* map, char* start, char* end,
+                              ErtsFreeSegDesc** under, ErtsFreeSegDesc** over)
+{
+    RBTNode* x = map->atree.root;
+
+    *under = NULL;
+    *over = NULL;
+    while (x) {
+	if (start < anode_to_desc(x)->start) {
+            RBT_ASSERT(end <= anode_to_desc(x)->start);
+            if (end == anode_to_desc(x)->start) {
+                RBT_ASSERT(!*over);
+                *over = anode_to_desc(x);
+            }
+            x = x->left;
+	}
+	else {
+            RBT_ASSERT(start >= anode_to_desc(x)->end);
+            if (start == anode_to_desc(x)->end) {
+                RBT_ASSERT(!*under);
+                *under = anode_to_desc(x);
+            }
+            x = x->right;
+        }
+    }
+}
+
+/* Initialize 'desc' and insert as new free segment [start->end].
+ * The new segment must not contain or be adjacent to any free segment in 'map'.
+ */
+static void insert_free_seg(ErtsFreeSegMap* map, ErtsFreeSegDesc* desc,
+                            char* start, char* end)
+{
+    desc->start = start;
+    desc->end = end;
+    rbt_insert(&map->atree, &desc->anode);
+    rbt_insert(&map->stree, &desc->snode);
+    map->nseg++;
+}
+
+/* Resize existing free segment 'desc' to [start->end].
+ * The new segment location must overlap the old location and
+ * it must not contain or be adjacent to any other free segment in 'map'.
+ */
+static void resize_free_seg(ErtsFreeSegMap* map, ErtsFreeSegDesc* desc,
+                            char* start, char* end)
+{
+#ifdef RBT_DEBUG
+    RBTNode* prev = rbt_prev_node(&desc->anode);
+    RBTNode* next = rbt_next_node(&desc->anode);
+    RBT_ASSERT(!prev || anode_to_desc(prev)->end < start);
+    RBT_ASSERT(!next || anode_to_desc(next)->start > end);
+#endif
+    rbt_delete(&map->stree, &desc->snode);
+    desc->start = start;
+    desc->end = end;
+    rbt_insert(&map->stree, &desc->snode);
+}
+
+/* Delete existing free segment 'desc' from 'map'.
+ */
+static void delete_free_seg(ErtsFreeSegMap* map, ErtsFreeSegDesc* desc)
+{
+    rbt_delete(&map->atree, &desc->anode);
+    rbt_delete(&map->stree, &desc->snode);
+    map->nseg--;
+}
+
+/* Lookup a free segment in 'map' with a size of at least 'need_sz' usable bytes.
+ */
+static ErtsFreeSegDesc* lookup_free_seg(ErtsFreeSegMap* map, SWord need_sz)
+{
+    RBTNode* x = map->stree.root;
+    ErtsFreeSegDesc* best_desc = NULL;
+    const enum SortOrder order = map->stree.order;
+
+    while (x) {
+        ErtsFreeSegDesc* desc = snode_to_desc(x);
+        SWord seg_sz = usable_size(order, desc);
+
+	if (seg_sz < need_sz) {
+	    x = x->right;
+	}
+	else {
+            best_desc = desc;
+	    x = x->left;
+	}
+    }
+    return best_desc;
+}
+
+struct build_arg_t
+{
+    Process* p;
+    Eterm* hp;
+    Eterm acc;
+};
+
+static void build_free_seg_tuple(RBTNode* node, void* arg)
+{
+    struct build_arg_t* a = (struct build_arg_t*)arg;
+    ErtsFreeSegDesc* desc = anode_to_desc(node);
+    Eterm start= erts_bld_uword(&a->hp, NULL, (UWord)desc->start);
+    Eterm end = erts_bld_uword(&a->hp, NULL, (UWord)desc->end);
+    Eterm tpl = TUPLE2(a->hp, start, end);
+
+    a->hp += 3;
+    a->acc = CONS(a->hp, tpl, a->acc);
+    a->hp += 2;
+}
+
+static
+Eterm build_free_seg_list(Process* p, ErtsFreeSegMap* map)
+{
+    struct build_arg_t barg;
+    Eterm* hp_end;
+    const Uint may_need = map->nseg * (2 + 3 + 2*2);  /* cons + tuple + bigs */
+
+    barg.p = p;
+    barg.hp = HAlloc(p, may_need);
+    hp_end = barg.hp + may_need;
+    barg.acc = NIL;
+    rbt_foreach_node(&map->atree, build_free_seg_tuple, &barg, 1);
+
+    RBT_ASSERT(barg.hp <= hp_end);
+    HRelease(p, hp_end, barg.hp);
+    return barg.acc;
+}
+
+#if ERTS_HAVE_OS_MMAP
+/* Implementation of os_mmap()/os_munmap()/os_mremap()... */
+
+#if HAVE_MMAP
+#  define ERTS_MMAP_PROT		(PROT_READ|PROT_WRITE)
+#  if defined(MAP_ANONYMOUS)
+#    define ERTS_MMAP_FLAGS		(MAP_ANON|MAP_PRIVATE)
+#    define ERTS_MMAP_FD		(-1)
+#  elif defined(MAP_ANON)
+#    define ERTS_MMAP_FLAGS		(MAP_ANON|MAP_PRIVATE)
+#    define ERTS_MMAP_FD		(-1)
+#  else
+#    define ERTS_MMAP_FLAGS		(MAP_PRIVATE)
+#    define ERTS_MMAP_FD		mmap_state.mmap_fd
+#  endif
+#endif
+
+static ERTS_INLINE void *
+os_mmap(void *hint_ptr, UWord size, int try_superalign)
+{
+#if HAVE_MMAP
+    void *res;
+#ifdef MAP_ALIGN
+    if (try_superalign)
+	res = mmap((void *) ERTS_SUPERALIGNED_SIZE, size, ERTS_MMAP_PROT,
+		   ERTS_MMAP_FLAGS|MAP_ALIGN, ERTS_MMAP_FD, 0);
+    else
+#endif
+	res = mmap((void *) hint_ptr, size, ERTS_MMAP_PROT,
+		   ERTS_MMAP_FLAGS, ERTS_MMAP_FD, 0);
+    if (res == MAP_FAILED)
+	return NULL;
+    return res;
+#elif HAVE_VIRTUALALLOC
+    return (void *) VirtualAlloc(NULL, (SIZE_T) size,
+				 MEM_COMMIT|MEM_RESERVE, PAGE_READWRITE);
+#else
+#  error "missing mmap() or similar"
+#endif
+}
+
+static ERTS_INLINE void
+os_munmap(void *ptr, UWord size)
+{
+#if HAVE_MMAP
+#ifdef ERTS_MMAP_DEBUG
+    int res =
+#endif
+	munmap(ptr, size);
+    ERTS_MMAP_ASSERT(res == 0);
+#elif HAVE_VIRTUALALLOC
+#ifdef DEBUG
+    BOOL res =
+#endif
+	VirtualFree((LPVOID) ptr, (SIZE_T) 0, MEM_RELEASE);
+    ERTS_MMAP_ASSERT(res != 0);
+#else
+#  error "missing munmap() or similar"
+#endif
+}
+
+#ifdef ERTS_HAVE_OS_MREMAP
+#  if HAVE_MREMAP
+#    if defined(__NetBSD__)
+#      define ERTS_MREMAP_FLAGS  (0)
+#    else
+#      define ERTS_MREMAP_FLAGS  (MREMAP_MAYMOVE)
+#    endif
+#  endif
+static ERTS_INLINE void *
+os_mremap(void *ptr, UWord old_size, UWord new_size, int try_superalign)
+{
+    void *new_seg;
+#if HAVE_MREMAP
+    new_seg = mremap(ptr, (size_t) old_size,
+#  if defined(__NetBSD__)
+		     NULL,
+#  endif
+		     (size_t) new_size, ERTS_MREMAP_FLAGS);
+    if (new_seg == (void *) MAP_FAILED)
+	return NULL;
+    return new_seg;
+#else
+#  error "missing mremap() or similar"
+#endif
+}
+#endif
+
+#ifdef ERTS_HAVE_OS_PHYSICAL_MEMORY_RESERVATION
+#if HAVE_MMAP
+
+#define ERTS_MMAP_RESERVE_PROT		(ERTS_MMAP_PROT)
+#define ERTS_MMAP_RESERVE_FLAGS		(ERTS_MMAP_FLAGS|MAP_FIXED)
+#define ERTS_MMAP_UNRESERVE_PROT	(PROT_NONE)
+#define ERTS_MMAP_UNRESERVE_FLAGS	(ERTS_MMAP_FLAGS|MAP_NORESERVE|MAP_FIXED)
+#define ERTS_MMAP_VIRTUAL_PROT		(PROT_NONE)
+#define ERTS_MMAP_VIRTUAL_FLAGS		(ERTS_MMAP_FLAGS|MAP_NORESERVE)
+
+static int
+os_reserve_physical(char *ptr, UWord size)
+{
+    void *res = mmap((void *) ptr, (size_t) size, ERTS_MMAP_RESERVE_PROT,
+		     ERTS_MMAP_RESERVE_FLAGS, ERTS_MMAP_FD, 0);
+    if (res == (void *) MAP_FAILED)
+	return 0;
+    return 1;
+}
+
+static void
+os_unreserve_physical(char *ptr, UWord size)
+{
+    void *res = mmap((void *) ptr, (size_t) size, ERTS_MMAP_UNRESERVE_PROT,
+		     ERTS_MMAP_UNRESERVE_FLAGS, ERTS_MMAP_FD, 0);
+    if (res == (void *) MAP_FAILED)
+	erl_exit(ERTS_ABORT_EXIT, "Failed to unreserve memory");
+}
+
+static void *
+os_mmap_virtual(char *ptr, UWord size)
+{
+    void *res = mmap((void *) ptr, (size_t) size, ERTS_MMAP_VIRTUAL_PROT,
+		     ERTS_MMAP_VIRTUAL_FLAGS, ERTS_MMAP_FD, 0);
+    if (res == (void *) MAP_FAILED)
+	return NULL;
+    return res;
+}
+
+#else
+#error "Missing reserve/unreserve physical memory implementation"
+#endif
+#endif /* ERTS_HAVE_OS_RESERVE_PHYSICAL_MEMORY */
+
+#endif /* ERTS_HAVE_OS_MMAP */
+
+static int reserve_noop(char *ptr, UWord size)
+{
+#ifdef ERTS_MMAP_DEBUG_FILL_AREAS
+    Uint32 *uip, *end = (Uint32 *) (ptr + size);
+
+    for (uip = (Uint32 *) ptr; uip < end; uip++)
+	ERTS_MMAP_ASSERT(*uip == (Uint32) 0xdeadbeef);
+    for (uip = (Uint32 *) ptr; uip < end; uip++)
+	*uip = (Uint32) 0xfeedfeed;
+#endif
+    return 1;
+}
+
+static void unreserve_noop(char *ptr, UWord size)
+{
+#ifdef ERTS_MMAP_DEBUG_FILL_AREAS
+    Uint32 *uip, *end = (Uint32 *) (ptr + size);
+
+    for (uip = (Uint32 *) ptr; uip < end; uip++)
+	*uip = (Uint32) 0xdeadbeef;
+#endif
+}
+
+static UWord
+alloc_desc_insert_free_seg(ErtsFreeSegMap *map, char* start, char* end)
+{
+    char *ptr;
+    ErtsFreeSegMap *da_map;
+    ErtsFreeSegDesc *desc = alloc_desc();
+    if (desc) {
+	insert_free_seg(map, desc, start, end);
+	return 0;
+    }
+
+    /*
+     * Ahh; ran out of free segment descriptors.
+     *
+     * First try to map a new page...
+     */
+
+#if ERTS_HAVE_OS_MMAP
+    if (!mmap_state.no_os_mmap) {
+        ptr = os_mmap(mmap_state.desc.new_area_hint, ERTS_PAGEALIGNED_SIZE, 0);
+        if (ptr) {
+            mmap_state.desc.new_area_hint = ptr+ERTS_PAGEALIGNED_SIZE;
+            ERTS_MMAP_SIZE_OS_INC(ERTS_PAGEALIGNED_SIZE);
+            add_free_desc_area(ptr, ptr+ERTS_PAGEALIGNED_SIZE);
+            desc = alloc_desc();
+            ERTS_MMAP_ASSERT(desc);
+            insert_free_seg(map, desc, start, end);
+            return 0;
+        }
+    }
+#endif
+
+    /*
+     * ...then try to find a good place in the supercarrier...
+     */
+    da_map = &mmap_state.sua.map;
+    desc = lookup_free_seg(da_map, ERTS_PAGEALIGNED_SIZE);
+    if (desc) {
+	if (mmap_state.reserve_physical(desc->start, ERTS_PAGEALIGNED_SIZE))
+	    ERTS_MMAP_SIZE_SC_SUA_INC(ERTS_PAGEALIGNED_SIZE);
+	else
+	    desc = NULL;
+	
+    }
+    else {
+	da_map = &mmap_state.sa.map;
+	desc = lookup_free_seg(da_map, ERTS_PAGEALIGNED_SIZE);
+	if (desc) {
+	    if (mmap_state.reserve_physical(desc->start, ERTS_PAGEALIGNED_SIZE))
+		ERTS_MMAP_SIZE_SC_SA_INC(ERTS_PAGEALIGNED_SIZE);
+	    else
+		desc = NULL;
+	}
+    }
+    if (desc) {
+	char *da_end = desc->start + ERTS_PAGEALIGNED_SIZE;
+	add_free_desc_area(desc->start, da_end);
+	if (da_end != desc->end)
+	    resize_free_seg(da_map, desc, da_end, desc->end);
+	else {
+	    delete_free_seg(da_map, desc);
+	    free_desc(desc);
+	}
+
+	desc = alloc_desc();
+	ERTS_MMAP_ASSERT(desc);
+	insert_free_seg(map, desc, start, end);
+	return 0;
+    }
+
+    /*
+     * ... and then as last resort use the first page of the
+     * free segment we are trying to insert for free descriptors.
+     */
+    ptr = start + ERTS_PAGEALIGNED_SIZE;
+    ERTS_MMAP_ASSERT(ptr <= end);
+
+    add_free_desc_area(start, ptr);
+
+    if (ptr != end) {
+	desc = alloc_desc();
+	ERTS_MMAP_ASSERT(desc);
+	insert_free_seg(map, desc, ptr, end);
+    }
+
+    return ERTS_PAGEALIGNED_SIZE;
+}
+
+void *
+erts_mmap(Uint32 flags, UWord *sizep)
+{
+    char *seg;
+    UWord asize = ERTS_PAGEALIGNED_CEILING(*sizep);
+
+    /* Map in premapped supercarrier */
+    if (mmap_state.supercarrier && !(ERTS_MMAPFLG_OS_ONLY & flags)) {
+	char *end;
+	ErtsFreeSegDesc *desc;
+	Uint32 superaligned = (ERTS_MMAPFLG_SUPERALIGNED & flags);
+
+	erts_smp_mtx_lock(&mmap_state.mtx);
+
+	ERTS_MMAP_OP_START(*sizep);
+
+	if (!superaligned) {
+	    desc = lookup_free_seg(&mmap_state.sua.map, asize);
+	    if (desc) {
+		seg = desc->start;
+		end = seg+asize;
+		if (!mmap_state.reserve_physical(seg, asize))
+		    goto supercarrier_reserve_failure;
+		if (desc->end == end) {
+		    delete_free_seg(&mmap_state.sua.map, desc);
+		    free_desc(desc);
+		}
+		else {
+		    ERTS_MMAP_ASSERT(end < desc->end);
+		    resize_free_seg(&mmap_state.sua.map, desc, end, desc->end);
+		}
+		ERTS_MMAP_SIZE_SC_SUA_INC(asize);
+		goto supercarrier_success;
+	    }
+
+	    if (asize <= mmap_state.sua.bot - mmap_state.sa.top) {
+		if (!mmap_state.reserve_physical(mmap_state.sua.bot - asize,
+						 asize))
+		    goto supercarrier_reserve_failure;
+		mmap_state.sua.bot -= asize;
+		seg = mmap_state.sua.bot;
+		ERTS_MMAP_SIZE_SC_SUA_INC(asize);
+		goto supercarrier_success;
+	    }
+	}
+
+	asize = ERTS_SUPERALIGNED_CEILING(asize);
+
+	desc = lookup_free_seg(&mmap_state.sa.map, asize);
+	if (desc) {
+	    char *start = seg = desc->start;
+	    seg = (char *) ERTS_SUPERALIGNED_CEILING(seg);
+	    end = seg+asize;
+	    if (!mmap_state.reserve_physical(start, (UWord) (end - start)))
+		goto supercarrier_reserve_failure;
+	    ERTS_MMAP_SIZE_SC_SA_INC(asize);
+	    if (desc->end == end) {
+		if (start != seg)
+		    resize_free_seg(&mmap_state.sa.map, desc, start, seg);
+		else {
+		    delete_free_seg(&mmap_state.sa.map, desc);
+		    free_desc(desc);
+		}
+	    }
+	    else {
+		ERTS_MMAP_ASSERT(end < desc->end);
+		resize_free_seg(&mmap_state.sa.map, desc, end, desc->end);
+		if (start != seg) {
+		    UWord ad_sz;
+		    ad_sz = alloc_desc_insert_free_seg(&mmap_state.sua.map,
+						       start, seg);
+		    start += ad_sz;
+		    if (start != seg)
+			mmap_state.unreserve_physical(start, (UWord) (seg - start));
+		}
+	    }
+	    goto supercarrier_success;
+	}
+
+	if (superaligned) {
+	    char *start = mmap_state.sa.top;
+	    seg = (char *) ERTS_SUPERALIGNED_CEILING(start);
+
+	    if (asize + (seg - start) <= mmap_state.sua.bot - start) {
+		end = seg + asize;
+		if (!mmap_state.reserve_physical(start, (UWord) (end - start)))
+		    goto supercarrier_reserve_failure;
+		mmap_state.sa.top = end;
+		ERTS_MMAP_SIZE_SC_SA_INC(asize);
+		if (start != seg) {
+		    UWord ad_sz;
+		    ad_sz = alloc_desc_insert_free_seg(&mmap_state.sua.map,
+						       start, seg);
+		    start += ad_sz;
+		    if (start != seg)
+			mmap_state.unreserve_physical(start, (UWord) (seg - start));
+		}
+		goto supercarrier_success;
+	    }
+
+	    desc = lookup_free_seg(&mmap_state.sua.map, asize + ERTS_SUPERALIGNED_SIZE);
+	    if (desc) {
+		char *org_start = desc->start;
+		char *org_end = desc->end;
+
+		seg = (char *) ERTS_SUPERALIGNED_CEILING(org_start);
+		end = seg + asize;
+		if (!mmap_state.reserve_physical(seg, (UWord) (org_end - seg)))
+		    goto supercarrier_reserve_failure;
+		ERTS_MMAP_SIZE_SC_SUA_INC(asize);
+		if (org_start != seg) {
+		    ERTS_MMAP_ASSERT(org_start < seg);
+		    resize_free_seg(&mmap_state.sua.map, desc, org_start, seg);
+		    desc = NULL;
+		}
+		if (end != org_end) {
+		    UWord ad_sz = 0;
+		    ERTS_MMAP_ASSERT(end < org_end);
+		    if (desc)
+			resize_free_seg(&mmap_state.sua.map, desc, end, org_end);
+		    else
+			ad_sz = alloc_desc_insert_free_seg(&mmap_state.sua.map,
+							   end, org_end);
+		    end += ad_sz;
+		    if (end != org_end)
+			mmap_state.unreserve_physical(end,
+						      (UWord) (org_end - end));
+		}
+		goto supercarrier_success;
+	    }
+	}
+
+	ERTS_MMAP_OP_ABORT();
+	erts_smp_mtx_unlock(&mmap_state.mtx);
+    }
+
+#if ERTS_HAVE_OS_MMAP
+    /* Map using OS primitives */
+    if (!(ERTS_MMAPFLG_SUPERCARRIER_ONLY & flags) && !mmap_state.no_os_mmap) {
+	if (!(ERTS_MMAPFLG_SUPERALIGNED & flags)) {
+	    seg = os_mmap(NULL, asize, 0);
+	    if (!seg)
+		goto failure;
+	}
+	else {
+	    asize = ERTS_SUPERALIGNED_CEILING(*sizep);
+	    seg = os_mmap(NULL, asize, 1);
+	    if (!seg)
+		goto failure;
+
+	    if (!ERTS_IS_SUPERALIGNED(seg)) {
+		char *ptr;
+		UWord sz;
+
+		os_munmap(seg, asize);
+
+		ptr = os_mmap(NULL, asize + ERTS_SUPERALIGNED_SIZE, 1);
+		if (!ptr)
+		    goto failure;
+
+		seg = (char *) ERTS_SUPERALIGNED_CEILING(ptr);
+		sz = (UWord) (seg - ptr);
+		ERTS_MMAP_ASSERT(sz <= ERTS_SUPERALIGNED_SIZE);
+		if (sz)
+		    os_munmap(ptr, sz);
+		sz = ERTS_SUPERALIGNED_SIZE - sz; 
+		if (sz)
+		    os_munmap(seg+asize, sz);
+	    }
+	}
+
+	ERTS_MMAP_OP_LCK(seg, *sizep, asize);
+	ERTS_MMAP_SIZE_OS_INC(asize);
+	*sizep = asize;
+	return (void *) seg;
+    }
+failure:
+#endif
+    ERTS_MMAP_OP_LCK(NULL, *sizep, 0);
+    *sizep = 0;
+    return NULL;
+
+supercarrier_success:
+
+#ifdef ERTS_MMAP_DEBUG
+    if (ERTS_MMAPFLG_SUPERALIGNED & flags) {
+	ERTS_MMAP_ASSERT(ERTS_IS_SUPERALIGNED(seg));
+	ERTS_MMAP_ASSERT(ERTS_IS_SUPERALIGNED(asize));
+    }
+    else {
+	ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(seg));
+	ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(asize));
+    }
+#endif
+
+    ERTS_MMAP_OP_END(seg, asize);
+    erts_smp_mtx_unlock(&mmap_state.mtx);
+
+    *sizep = asize;
+    return (void *) seg;
+
+supercarrier_reserve_failure:
+    erts_smp_mtx_unlock(&mmap_state.mtx);
+    *sizep = 0;
+    return NULL;
+}
+
+void
+erts_munmap(Uint32 flags, void *ptr, UWord size)
+{
+    ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(ptr));
+    ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(size));
+
+    if (!ERTS_MMAP_IN_SUPERCARRIER(ptr)) {
+	ERTS_MMAP_ASSERT(!mmap_state.no_os_mmap);
+#if ERTS_HAVE_OS_MMAP
+	ERTS_MUNMAP_OP_LCK(ptr, size);
+	ERTS_MMAP_SIZE_OS_DEC(size);
+	os_munmap(ptr, size);
+#endif
+    }
+    else {
+	char *start, *end;
+	ErtsFreeSegMap *map;
+	ErtsFreeSegDesc *prev, *next, *desc;
+	UWord ad_sz = 0;
+
+	ERTS_MMAP_ASSERT(mmap_state.supercarrier);
+
+	start = (char *) ptr;
+	end = start + size;
+
+	erts_smp_mtx_lock(&mmap_state.mtx);
+
+	ERTS_MUNMAP_OP(ptr, size);
+
+	if (ERTS_MMAP_IN_SUPERALIGNED_AREA(ptr)) {
+
+	    map = &mmap_state.sa.map;
+	    adjacent_free_seg(map, start, end, &prev, &next);
+
+	    ERTS_MMAP_SIZE_SC_SA_DEC(size);
+	    if (end == mmap_state.sa.top) {
+		ERTS_MMAP_ASSERT(!next);
+		if (prev) {
+		    start = prev->start;
+		    delete_free_seg(map, prev);
+		    free_desc(prev);
+		}
+		mmap_state.sa.top = start;
+		goto supercarrier_success;
+	    }
+	}
+	else {
+	    map = &mmap_state.sua.map;
+	    adjacent_free_seg(map, start, end, &prev, &next);
+
+	    ERTS_MMAP_SIZE_SC_SUA_DEC(size);
+	    if (start == mmap_state.sua.bot) {
+		ERTS_MMAP_ASSERT(!prev);
+		if (next) {
+		    end = next->end;
+		    delete_free_seg(map, next);
+		    free_desc(next);
+		}
+		mmap_state.sua.bot = end;
+		goto supercarrier_success;
+	    }
+	}
+
+	desc = NULL;
+
+	if (next) {
+	    ERTS_MMAP_ASSERT(end < next->end);
+	    end = next->end;
+	    if (prev) {
+		delete_free_seg(map, next);
+		free_desc(next);
+		goto save_prev;
+	    }
+	    desc = next;
+	} else if (prev) {
+	save_prev:
+	    ERTS_MMAP_ASSERT(prev->start < start);
+	    start = prev->start;
+	    desc = prev;
+	}
+
+	if (desc)
+	    resize_free_seg(map, desc, start, end);
+	else
+	    ad_sz = alloc_desc_insert_free_seg(map, start, end);
+	
+    supercarrier_success: {
+	    UWord unres_sz;
+
+	    ERTS_MMAP_ASSERT(size >= ad_sz);
+	    unres_sz = size - ad_sz;
+	    if (unres_sz)
+		mmap_state.unreserve_physical(((char *) ptr) + ad_sz, unres_sz);
+
+            erts_smp_mtx_unlock(&mmap_state.mtx);
+	}
+    }
+}
+
+static void *
+remap_move(Uint32 flags, void *ptr, UWord old_size, UWord *sizep)
+{
+    UWord size = *sizep;
+    void *new_ptr = erts_mmap(flags, &size);
+    if (!new_ptr)
+	return NULL;
+    *sizep = size;
+    if (old_size < size)
+	size = old_size;
+    sys_memcpy(new_ptr, ptr, (size_t) size);
+    erts_munmap(flags, ptr, old_size);
+    return new_ptr;
+}
+
+void *
+erts_mremap(Uint32 flags, void *ptr, UWord old_size, UWord *sizep)
+{
+    void *new_ptr;
+    Uint32 superaligned;
+    UWord asize;
+
+    ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(ptr));
+    ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(old_size));
+    ERTS_MMAP_ASSERT(sizep && ERTS_IS_PAGEALIGNED(*sizep));
+
+    if (!ERTS_MMAP_IN_SUPERCARRIER(ptr)) {
+
+	ERTS_MMAP_ASSERT(!mmap_state.no_os_mmap);
+
+	if (!(ERTS_MMAPFLG_OS_ONLY & flags) && mmap_state.supercarrier) {
+	    new_ptr = remap_move(ERTS_MMAPFLG_SUPERCARRIER_ONLY|flags, ptr,
+				 old_size, sizep);
+	    if (new_ptr)
+		return new_ptr;
+	}
+
+	if (ERTS_MMAPFLG_SUPERCARRIER_ONLY & flags) {
+	    ERTS_MREMAP_OP_LCK(NULL, ptr, old_size, *sizep, old_size);
+	    return NULL;
+	}
+
+#if ERTS_HAVE_OS_MREMAP || ERTS_HAVE_GENUINE_OS_MMAP
+	superaligned = (ERTS_MMAPFLG_SUPERALIGNED & flags);
+
+	if (superaligned) {
+	    asize = ERTS_SUPERALIGNED_CEILING(*sizep);
+	    if (asize == old_size && ERTS_IS_SUPERALIGNED(ptr)) {
+		ERTS_MREMAP_OP_LCK(ptr, ptr, old_size, *sizep, asize);
+		*sizep = asize;
+		return ptr;
+	    }
+	}
+	else {
+	    asize = ERTS_PAGEALIGNED_CEILING(*sizep);
+	    if (asize == old_size) {
+		ERTS_MREMAP_OP_LCK(ptr, ptr, old_size, *sizep, asize);
+		*sizep = asize;
+		return ptr;
+	    }
+	}
+
+#if ERTS_HAVE_GENUINE_OS_MMAP
+	if (asize < old_size
+	    && (!superaligned
+		|| ERTS_IS_SUPERALIGNED(ptr))) {
+	    UWord um_sz;
+	    new_ptr = ((char *) ptr) + asize;
+	    ERTS_MMAP_ASSERT((((char *)ptr) + old_size) > (char *) new_ptr);
+	    um_sz = (UWord) ((((char *) ptr) + old_size) - (char *) new_ptr); 
+	    ERTS_MMAP_SIZE_OS_DEC(um_sz);
+	    os_munmap(new_ptr, um_sz);
+	    ERTS_MREMAP_OP_LCK(ptr, ptr, old_size, *sizep, asize);
+	    *sizep = asize;
+	    return ptr;
+	}
+#endif
+#if ERTS_HAVE_OS_MREMAP
+	if (superaligned)
+	    return remap_move(flags, new_ptr, old_size, sizep);
+	else {
+	    new_ptr = os_mremap(ptr, old_size, asize, 0);
+	    if (!new_ptr)
+		return NULL;
+	    if (asize > old_size)
+		ERTS_MMAP_SIZE_OS_INC(asize - old_size);
+	    else
+		ERTS_MMAP_SIZE_OS_DEC(old_size - asize);
+	    ERTS_MREMAP_OP_LCK(new_ptr, ptr, old_size, *sizep, asize);
+	    *sizep = asize;
+	    return new_ptr;
+	}
+#endif
+#endif
+    }
+    else { /* In super carrier */
+	char *start, *end, *new_end;
+	ErtsFreeSegMap *map;
+	ErtsFreeSegDesc *prev, *next;
+	UWord ad_sz = 0;
+
+	ERTS_MMAP_ASSERT(mmap_state.supercarrier);
+
+	if (ERTS_MMAPFLG_OS_ONLY & flags)
+	    return remap_move(flags, ptr, old_size, sizep);
+
+	superaligned = (ERTS_MMAPFLG_SUPERALIGNED & flags);
+
+	asize = (superaligned
+		 ? ERTS_SUPERALIGNED_CEILING(*sizep)
+		 : ERTS_PAGEALIGNED_CEILING(*sizep));
+
+	erts_smp_mtx_lock(&mmap_state.mtx);
+
+	if (ERTS_MMAP_IN_SUPERALIGNED_AREA(ptr)
+	    ? (!superaligned && lookup_free_seg(&mmap_state.sua.map, asize))
+	    : (superaligned && lookup_free_seg(&mmap_state.sa.map, asize))) {
+	    erts_smp_mtx_unlock(&mmap_state.mtx);
+	    /*
+	     * Segment currently in wrong area (due to a previous memory
+	     * shortage), move it to the right area.
+	     * (remap_move() will succeed)
+	     */
+	    return remap_move(ERTS_MMAPFLG_SUPERCARRIER_ONLY|flags, ptr,
+			      old_size, sizep);
+	}
+
+	ERTS_MREMAP_OP_START(ptr, old_size, *sizep);
+
+	if (asize == old_size) {
+	    new_ptr = ptr;
+	    goto supercarrier_resize_success;
+	}
+
+	start = (char *) ptr;
+	end = start + old_size;
+	new_end = start+asize;
+
+	ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(ptr));
+	ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(old_size));
+	ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(asize));
+
+	if (asize < old_size) {
+	    UWord unres_sz;
+	    new_ptr = ptr;
+	    if (!ERTS_MMAP_IN_SUPERALIGNED_AREA(ptr)) {
+		map = &mmap_state.sua.map;
+		ERTS_MMAP_SIZE_SC_SUA_DEC(old_size - asize);
+	    }
+	    else {
+		if (end == mmap_state.sa.top) {
+		    mmap_state.sa.top = new_end;
+		    mmap_state.unreserve_physical(((char *) ptr) + asize,
+						  old_size - asize);
+		    goto supercarrier_resize_success;
+		}
+		ERTS_MMAP_SIZE_SC_SA_DEC(old_size - asize);
+		map = &mmap_state.sa.map;
+	    }
+	    
+	    adjacent_free_seg(map, start, end, &prev, &next);
+
+	    if (next)
+		resize_free_seg(map, next, new_end, next->end);
+	    else
+		ad_sz = alloc_desc_insert_free_seg(map, new_end, end);
+	    ERTS_MMAP_ASSERT(old_size - asize >= ad_sz);
+	    unres_sz = old_size - asize - ad_sz;
+	    if (unres_sz)
+		mmap_state.unreserve_physical(((char *) ptr) + asize + ad_sz,
+					      unres_sz);
+	    goto supercarrier_resize_success;
+	}
+
+	if (!ERTS_MMAP_IN_SUPERALIGNED_AREA(ptr)) {
+	    ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(ptr));
+	    ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(old_size));
+	    ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(asize));
+
+	    adjacent_free_seg(&mmap_state.sua.map, start, end, &prev, &next);
+
+	    if (next && new_end <= next->end) {
+		if (!mmap_state.reserve_physical(((char *) ptr) + old_size,
+						 asize - old_size))
+		    goto supercarrier_reserve_failure;
+		if (new_end < next->end)
+		    resize_free_seg(&mmap_state.sua.map, next, new_end, next->end);
+		else {
+		    delete_free_seg(&mmap_state.sua.map, next);
+		    free_desc(next);
+		}
+		new_ptr = ptr;
+		ERTS_MMAP_SIZE_SC_SUA_INC(asize - old_size);
+		goto supercarrier_resize_success;
+	    }
+	}
+	else { /* Superaligned area */
+
+	    if (end == mmap_state.sa.top) {
+		if (new_end <= mmap_state.sua.bot) {
+		    if (!mmap_state.reserve_physical(((char *) ptr) + old_size,
+						     asize - old_size))
+			goto supercarrier_reserve_failure;
+		    mmap_state.sa.top = new_end;
+		    new_ptr = ptr;
+		    ERTS_MMAP_SIZE_SC_SA_INC(asize - old_size);
+		    goto supercarrier_resize_success;
+		}
+	    }
+	    else {
+		adjacent_free_seg(&mmap_state.sa.map, start, end, &prev, &next);
+		if (next && new_end <= next->end) {
+		    if (!mmap_state.reserve_physical(((char *) ptr) + old_size,
+						     asize - old_size))
+			goto supercarrier_reserve_failure;
+		    if (new_end < next->end)
+			resize_free_seg(&mmap_state.sa.map, next, new_end, next->end);
+		    else {
+			delete_free_seg(&mmap_state.sa.map, next);
+			free_desc(next);
+		    }
+		    new_ptr = ptr;
+		    ERTS_MMAP_SIZE_SC_SA_INC(asize - old_size);
+		    goto supercarrier_resize_success;
+		}
+	    }
+	}
+
+	ERTS_MMAP_OP_ABORT();
+	erts_smp_mtx_unlock(&mmap_state.mtx);
+
+	/* Failed to resize... */
+    }
+
+    return remap_move(flags, ptr, old_size, sizep);
+
+supercarrier_resize_success:
+
+#ifdef ERTS_MMAP_DEBUG
+    if ((ERTS_MMAPFLG_SUPERALIGNED & flags)
+	|| ERTS_MMAP_IN_SUPERALIGNED_AREA(new_ptr)) {
+	ERTS_MMAP_ASSERT(ERTS_IS_SUPERALIGNED(new_ptr));
+	ERTS_MMAP_ASSERT(ERTS_IS_SUPERALIGNED(asize));
+    }
+    else {
+	ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(new_ptr));
+	ERTS_MMAP_ASSERT(ERTS_IS_PAGEALIGNED(asize));
+    }
+#endif
+
+    ERTS_MREMAP_OP_END(new_ptr, asize);
+    erts_smp_mtx_unlock(&mmap_state.mtx);
+
+    *sizep = asize;
+    return new_ptr;
+
+supercarrier_reserve_failure:
+    ERTS_MREMAP_OP_END(NULL, old_size);
+    erts_smp_mtx_unlock(&mmap_state.mtx);
+    *sizep = old_size;
+    return NULL;
+    
+}
+
+int erts_mmap_in_supercarrier(void *ptr)
+{
+    return ERTS_MMAP_IN_SUPERCARRIER(ptr);
+}
+
+
+static struct {
+    Eterm total;
+    Eterm total_sa;
+    Eterm total_sua;
+    Eterm used;
+    Eterm used_sa;
+    Eterm used_sua;
+    Eterm max;
+    Eterm allocated;
+    Eterm reserved;
+    Eterm sizes;
+    Eterm free_segs;
+    Eterm supercarrier;
+    Eterm os;
+    Eterm scs;
+    Eterm sco;
+    Eterm scrpm;
+    Eterm scmgc;
+
+    int is_initialized;
+    erts_mtx_t init_mutex;
+}am;
+
+static void ERTS_INLINE atom_init(Eterm *atom, char *name)
+{
+    *atom = am_atom_put(name, strlen(name));
+}
+#define AM_INIT(AM) atom_init(&am.AM, #AM)
+
+static void init_atoms(void)
+{
+    erts_mtx_lock(&am.init_mutex);
+
+    if (!am.is_initialized) {
+        AM_INIT(total);
+        AM_INIT(total_sa);
+        AM_INIT(total_sua);
+        AM_INIT(used);
+        AM_INIT(used_sa);
+        AM_INIT(used_sua);
+        AM_INIT(max);
+        AM_INIT(allocated);
+        AM_INIT(reserved);
+        AM_INIT(sizes);
+        AM_INIT(free_segs);
+        AM_INIT(supercarrier);
+        AM_INIT(os);
+        AM_INIT(scs);
+        AM_INIT(sco);
+        AM_INIT(scrpm);
+        AM_INIT(scmgc);
+        am.is_initialized = 1;
+    }
+    erts_mtx_unlock(&am.init_mutex);
+};
+
+
+#ifdef HARD_DEBUG_MSEG
+static void hard_dbg_mseg_init(void);
+#endif
+
+void
+erts_mmap_init(ErtsMMapInit *init)
+{
+    int virtual_map = 0;
+    char *start = NULL, *end = NULL;
+    UWord pagesize;
+#if defined(__WIN32__)
+    SYSTEM_INFO sysinfo;
+    GetSystemInfo(&sysinfo);
+    pagesize = (UWord) sysinfo.dwPageSize;
+#elif defined(_SC_PAGESIZE)
+    pagesize = (UWord) sysconf(_SC_PAGESIZE);
+#elif defined(HAVE_GETPAGESIZE)
+    pagesize = (UWord) getpagesize();
+#else
+#  error "Do not know how to get page size"
+#endif
+#if defined(HARD_DEBUG)  || 0
+    erts_fprintf(stderr, "erts_mmap: scs = %bpu\n", init->scs);
+    erts_fprintf(stderr, "erts_mmap: sco = %i\n", init->sco);
+    erts_fprintf(stderr, "erts_mmap: scmgc = %i\n", init->scmgc);
+#endif
+    erts_page_inv_mask = pagesize - 1;
+    if (pagesize & erts_page_inv_mask)
+	erl_exit(-1, "erts_mmap: Invalid pagesize: %bpu\n",
+		 pagesize);
+
+    ERTS_MMAP_OP_RINGBUF_INIT();
+
+    erts_have_erts_mmap = 0;
+
+    mmap_state.supercarrier = 0;
+    mmap_state.reserve_physical = reserve_noop;
+    mmap_state.unreserve_physical = unreserve_noop;
+
+#if HAVE_MMAP && !defined(MAP_ANON)
+    mmap_state.mmap_fd = open("/dev/zero", O_RDWR);
+    if (mmap_state.mmap_fd < 0)
+	erl_exit(-1, "erts_mmap: Failed to open /dev/zero\n");
+#endif
+
+    erts_smp_mtx_init(&mmap_state.mtx, "erts_mmap");
+    erts_mtx_init(&am.init_mutex, "mmap_init_atoms");
+
+#ifdef ERTS_HAVE_OS_PHYSICAL_MEMORY_RESERVATION
+    if (init->virtual_range.start) {
+	char *ptr;
+	UWord sz;
+	ptr = (char *) ERTS_PAGEALIGNED_CEILING(init->virtual_range.start);
+	end = (char *) ERTS_PAGEALIGNED_FLOOR(init->virtual_range.end);
+	sz = end - ptr;
+	start = os_mmap_virtual(ptr, sz);
+	if (!start || start > ptr || start >= end)
+	    erl_exit(-1,
+		     "erts_mmap: Failed to create virtual range for super carrier\n");
+	sz = start - ptr;
+	if (sz)
+	    os_munmap(end, sz);
+	mmap_state.reserve_physical = os_reserve_physical;
+	mmap_state.unreserve_physical = os_unreserve_physical;
+	virtual_map = 1;
+    }
+    else
+#endif
+	if (init->predefined_area.start) {
+	    start = init->predefined_area.start;
+	    end = init->predefined_area.end;
+	    if (end != (void *) 0 && end < start)
+		end = start;
+    }
+#if ERTS_HAVE_OS_MMAP
+    else if (init->scs) {
+	UWord sz;
+	sz = ERTS_PAGEALIGNED_CEILING(init->scs);
+#ifdef ERTS_HAVE_OS_PHYSICAL_MEMORY_RESERVATION
+	if (!init->scrpm) {
+	    start = os_mmap_virtual(NULL, sz);
+	    mmap_state.reserve_physical = os_reserve_physical;
+	    mmap_state.unreserve_physical = os_unreserve_physical;
+	    virtual_map = 1;
+	}
+	else
+#endif
+	{
+	    /*
+	     * The whole supercarrier will by physically
+	     * reserved all the time.
+	     */
+	    start = os_mmap(NULL, sz, 1);
+	}
+	if (!start)
+	    erl_exit(-1,
+		     "erts_mmap: Failed to create super carrier of size %bpu MB\n",
+		     init->scs/1024/1024);
+	end = start + sz;
+#ifdef ERTS_MMAP_DEBUG_FILL_AREAS
+	if (!virtual_map) {
+	    Uint32 *uip;
+
+	    for (uip = (Uint32 *) start; uip < (Uint32 *) end; uip++)
+		*uip = (Uint32) 0xdeadbeef;
+	}
+#endif
+    }
+    if (!mmap_state.no_os_mmap)
+	erts_have_erts_mmap |= ERTS_HAVE_ERTS_OS_MMAP;
+#endif
+
+    mmap_state.no.free_seg_descs = 0;
+    mmap_state.no.free_segs.curr = 0;
+    mmap_state.no.free_segs.max = 0;
+
+    mmap_state.size.supercarrier.total = 0;
+    mmap_state.size.supercarrier.used.total = 0;
+    mmap_state.size.supercarrier.used.sa = 0;
+    mmap_state.size.supercarrier.used.sua = 0;
+    mmap_state.size.os.used = 0;
+
+    mmap_state.desc.new_area_hint = NULL;
+
+    if (!start) {
+	mmap_state.sa.bot = NULL;
+	mmap_state.sua.top = NULL;
+	mmap_state.sa.bot = NULL;
+	mmap_state.sua.top = NULL;
+	mmap_state.no_os_mmap = 0;
+        mmap_state.supercarrier = 0;
+    }
+    else {
+	size_t desc_size;
+
+	mmap_state.no_os_mmap = init->sco;
+
+	desc_size = init->scmgc;
+	if (desc_size < 100)
+	    desc_size = 100;
+	desc_size *= sizeof(ErtsFreeSegDesc);
+	if ((desc_size
+	     + ERTS_SUPERALIGNED_SIZE
+	     + ERTS_PAGEALIGNED_SIZE) > end - start)
+	    erl_exit(-1, "erts_mmap: No space for segments in super carrier\n");
+
+	mmap_state.sa.bot = start;
+	mmap_state.sa.bot += desc_size;
+	mmap_state.sa.bot = (char *) ERTS_SUPERALIGNED_CEILING(mmap_state.sa.bot);
+	mmap_state.sa.top = mmap_state.sa.bot;
+	mmap_state.sua.top = end;
+	mmap_state.sua.bot = mmap_state.sua.top;
+
+	mmap_state.size.supercarrier.used.total += (UWord) (mmap_state.sa.bot - start);
+
+	mmap_state.desc.free_list = NULL;
+        mmap_state.desc.reserved = 0;
+
+	if (end == (void *) 0) {
+	    /*
+	     * Very unlikely, but we need a guarantee
+	     * that `mmap_state.sua.top` always will
+	     * compare as larger than all segment pointers
+	     * into the super carrier...
+	     */
+	    mmap_state.sua.top -= ERTS_PAGEALIGNED_SIZE;
+	    mmap_state.size.supercarrier.used.total += ERTS_PAGEALIGNED_SIZE;
+#ifdef ERTS_HAVE_OS_PHYSICAL_MEMORY_RESERVATION
+	    if (!virtual_map || os_reserve_physical(mmap_state.sua.top, ERTS_PAGEALIGNED_SIZE))
+#endif
+		add_free_desc_area(mmap_state.sua.top, end);
+            mmap_state.desc.reserved += (end - mmap_state.sua.top) / sizeof(ErtsFreeSegDesc);
+	}
+
+	mmap_state.size.supercarrier.total = (UWord) (mmap_state.sua.top - start);
+
+	/*
+	 * Area before (and after) super carrier
+	 * will be used for free segment descritors.
+	 */
+#ifdef ERTS_HAVE_OS_PHYSICAL_MEMORY_RESERVATION
+	if (virtual_map && !os_reserve_physical(start, mmap_state.sa.bot - start))
+	    erl_exit(-1, "erts_mmap: Failed to reserve physical memory for descriptors\n");
+#endif
+	mmap_state.desc.unused_start = start;
+	mmap_state.desc.unused_end = mmap_state.sa.bot;
+        mmap_state.desc.reserved += ((mmap_state.desc.unused_end - start)
+                                     / sizeof(ErtsFreeSegDesc));
+
+	init_free_seg_map(&mmap_state.sa.map, SA_SZ_ADDR_ORDER);
+	init_free_seg_map(&mmap_state.sua.map, SZ_REVERSE_ADDR_ORDER);
+
+	mmap_state.supercarrier = 1;
+	erts_have_erts_mmap |= ERTS_HAVE_ERTS_SUPERCARRIER_MMAP;
+
+	mmap_state.desc.new_area_hint = end;
+
+    }
+
+#if !ERTS_HAVE_OS_MMAP
+    mmap_state.no_os_mmap = 1;
+#endif
+
+#ifdef HARD_DEBUG_MSEG
+    hard_dbg_mseg_init();
+#endif
+}
+
+
+static ERTS_INLINE void
+add_2tup(Uint **hpp, Uint *szp, Eterm *lp, Eterm el1, Eterm el2)
+{
+    *lp = erts_bld_cons(hpp, szp, erts_bld_tuple(hpp, szp, 2, el1, el2), *lp);
+}
+
+Eterm erts_mmap_info(int *print_to_p,
+                     void *print_to_arg,
+                     Eterm** hpp, Uint* szp,
+                     struct erts_mmap_info_struct* emis)
+{
+    Eterm size_tags[] = { am.total, am.total_sa, am.total_sua, am.used, am.used_sa, am.used_sua };
+    Eterm seg_tags[] = { am.used, am.max, am.allocated, am.reserved, am.used_sa, am.used_sua };
+    Eterm group[2];
+    Eterm group_tags[] = { am.sizes, am.free_segs };
+    Eterm list[2];
+    Eterm list_tags[2]; /* { am.supercarrier, am.os } */
+    int lix;
+    Eterm res = THE_NON_VALUE;
+
+    if (!hpp) {
+        erts_smp_mtx_lock(&mmap_state.mtx);
+        emis->sizes[0] = mmap_state.size.supercarrier.total;
+        emis->sizes[1] = mmap_state.sa.top  - mmap_state.sa.bot;
+        emis->sizes[2] = mmap_state.sua.top - mmap_state.sua.bot;
+        emis->sizes[3] = mmap_state.size.supercarrier.used.total;
+        emis->sizes[4] = mmap_state.size.supercarrier.used.sa;
+        emis->sizes[5] = mmap_state.size.supercarrier.used.sua;
+
+        emis->segs[0] = mmap_state.no.free_segs.curr;
+        emis->segs[1] = mmap_state.no.free_segs.max;
+        emis->segs[2] = mmap_state.no.free_seg_descs;
+        emis->segs[3] = mmap_state.desc.reserved;
+        emis->segs[4] = mmap_state.sa.map.nseg;
+        emis->segs[5] = mmap_state.sua.map.nseg;
+
+        emis->os_used = mmap_state.size.os.used;
+        erts_smp_mtx_unlock(&mmap_state.mtx);
+    }
+
+    if (print_to_p) {
+        int to = *print_to_p;
+	void *arg = print_to_arg;
+        if (mmap_state.supercarrier) {
+            const char* prefix = "supercarrier ";
+            erts_print(to, arg, "%stotal size: %bpu\n", prefix, emis->sizes[0]);
+            erts_print(to, arg, "%stotal sa size: %bpu\n", prefix, emis->sizes[1]);
+            erts_print(to, arg, "%stotal sua size: %bpu\n", prefix, emis->sizes[2]);
+            erts_print(to, arg, "%sused size: %bpu\n", prefix, emis->sizes[3]);
+            erts_print(to, arg, "%sused sa size: %bpu\n", prefix, emis->sizes[4]);
+            erts_print(to, arg, "%sused sua size: %bpu\n", prefix, emis->sizes[5]);
+            erts_print(to, arg, "%sused free segs: %bpu\n", prefix, emis->segs[0]);
+            erts_print(to, arg, "%smax free segs: %bpu\n", prefix, emis->segs[1]);
+            erts_print(to, arg, "%sallocated free segs: %bpu\n", prefix, emis->segs[2]);
+            erts_print(to, arg, "%sreserved free segs: %bpu\n", prefix, emis->segs[3]);
+            erts_print(to, arg, "%ssa free segs: %bpu\n", prefix, emis->segs[4]);
+            erts_print(to, arg, "%ssua free segs: %bpu\n", prefix, emis->segs[5]);
+        }
+        if (!mmap_state.no_os_mmap) {
+            erts_print(to, arg, "os mmap size used: %bpu\n", emis->os_used);
+        }
+    }
+
+
+    if (hpp || szp) {
+        if (!am.is_initialized) {
+            init_atoms();
+        }
+
+        lix = 0;
+        if (mmap_state.supercarrier) {
+            group[0] = erts_bld_atom_uword_2tup_list(hpp, szp,
+                                                     sizeof(size_tags)/sizeof(Eterm),
+                                                     size_tags, emis->sizes);
+            group[1] = erts_bld_atom_uword_2tup_list(hpp, szp,
+                                                     sizeof(seg_tags)/sizeof(Eterm),
+                                                     seg_tags, emis->segs);
+            list[lix] = erts_bld_2tup_list(hpp, szp, 2, group_tags, group);
+            list_tags[lix] = am.supercarrier;
+            lix++;
+        }
+
+        if (!mmap_state.no_os_mmap) {
+            group[0] = erts_bld_atom_uword_2tup_list(hpp, szp,
+                                                      1, &am.used, &emis->os_used);
+            list[lix] = erts_bld_2tup_list(hpp, szp, 1, group_tags, group);
+            list_tags[lix] = am.os;
+            lix++;
+        }
+        res = erts_bld_2tup_list(hpp, szp, lix, list_tags, list);
+    }
+    return res;
+}
+
+Eterm erts_mmap_info_options(char *prefix,
+                             int *print_to_p,
+                             void *print_to_arg,
+                             Uint **hpp,
+                             Uint *szp)
+{
+    const UWord scs = mmap_state.sua.top - mmap_state.sa.bot;
+    const Eterm sco = mmap_state.no_os_mmap ? am_true : am_false;
+    const Eterm scrpm = (mmap_state.reserve_physical == reserve_noop) ? am_true : am_false;
+    Eterm res = THE_NON_VALUE;
+
+    if (print_to_p) {
+        int to = *print_to_p;
+	void *arg = print_to_arg;
+        erts_print(to, arg, "%sscs: %bpu\n", prefix, scs);
+        if (mmap_state.supercarrier) {
+            erts_print(to, arg, "%ssco: %T\n", prefix, sco);
+            erts_print(to, arg, "%sscrpm: %T\n", prefix, scrpm);
+            erts_print(to, arg, "%sscmgc: %beu\n", prefix, mmap_state.desc.reserved);
+        }
+    }
+
+    if (hpp || szp) {
+        if (!am.is_initialized) {
+            init_atoms();
+        }
+
+        res = NIL;
+        if (mmap_state.supercarrier) {
+            add_2tup(hpp, szp, &res, am.scmgc,
+                     erts_bld_uint(hpp,szp, mmap_state.desc.reserved));
+            add_2tup(hpp, szp, &res, am.scrpm, scrpm);
+            add_2tup(hpp, szp, &res, am.sco, sco);
+        }
+        add_2tup(hpp, szp, &res, am.scs, erts_bld_uword(hpp, szp, scs));
+    }
+    return res;
+}
+
+
+Eterm erts_mmap_debug_info(Process* p)
+{
+    if (mmap_state.supercarrier) {
+        ERTS_DECL_AM(sabot);
+        ERTS_DECL_AM(satop);
+        ERTS_DECL_AM(suabot);
+        ERTS_DECL_AM(suatop);
+        Eterm sa_list, sua_list, list;
+        Eterm tags[] = { AM_sabot, AM_satop, AM_suabot, AM_suatop };
+        UWord values[4];
+        Eterm *hp, *hp_end;
+        Uint may_need;
+        const Uint PTR_BIG_SZ = HALFWORD_HEAP ? 3 : 2;
+
+        erts_smp_mtx_lock(&mmap_state.mtx);
+        values[0] = (UWord)mmap_state.sa.bot;
+        values[1] = (UWord)mmap_state.sa.top;
+        values[2] = (UWord)mmap_state.sua.bot;
+        values[3] = (UWord)mmap_state.sua.top;
+        sa_list = build_free_seg_list(p, &mmap_state.sa.map);
+        sua_list = build_free_seg_list(p, &mmap_state.sua.map);
+        erts_smp_mtx_unlock(&mmap_state.mtx);
+
+        may_need = 4*(2+3+PTR_BIG_SZ) + 2*(2+3);
+        hp = HAlloc(p, may_need);
+        hp_end = hp + may_need;
+
+        list = erts_bld_atom_uword_2tup_list(&hp, NULL,
+                                            sizeof(values)/sizeof(*values),
+                                            tags, values);
+
+        sa_list = TUPLE2(hp, am_atom_put("sa_free_segs",12), sa_list); hp+=3;
+        sua_list = TUPLE2(hp, am_atom_put("sua_free_segs",13), sua_list); hp+=3;
+        list = CONS(hp, sua_list, list); hp+=2;
+        list = CONS(hp, sa_list, list); hp+=2;
+
+        ASSERT(hp <= hp_end);
+        HRelease(p, hp_end, hp);
+        return list;
+    }
+    else {
+        return am_undefined;
+    }
+}
+
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Debug functions                                                           *
+\*                                                                           */
+
+
+#ifdef HARD_DEBUG
+
+static int rbt_assert_is_member(RBTNode* root, RBTNode* node)
+{
+    while (node != root) {
+	RBT_ASSERT(parent(node));
+	RBT_ASSERT(parent(node)->left == node || parent(node)->right == node);
+	node = parent(node);
+    }
+    return 1;
+}
+
+
+#if 0
+#  define PRINT_TREE
+#else
+#  undef PRINT_TREE
+#endif
+
+#ifdef PRINT_TREE
+static void print_tree(enum SortOrder order, RBTNode*);
+#endif
+
+/*
+ * Checks that the order between parent and children are correct,
+ * and that the Red-Black Tree properies are satisfied. if size > 0,
+ * check_tree() returns the node that satisfies "address order first fit"
+ *
+ * The Red-Black Tree properies are:
+ *   1. Every node is either red or black.
+ *   2. Every leaf (NIL) is black.
+ *   3. If a node is red, then both its children are black.
+ *   4. Every simple path from a node to a descendant leaf
+ *      contains the same number of black nodes.
+ *
+ */
+
+struct check_arg_t {
+    RBTree* tree;
+    ErtsFreeSegDesc* prev_seg;
+    Uint size;
+    RBTNode *res;
+};
+static void check_node_callback(RBTNode* x, void* arg);
+
+
+static RBTNode *
+check_tree(RBTree* tree, Uint size)
+{
+    struct check_arg_t carg;
+    carg.tree = tree;
+    carg.prev_seg = NULL;
+    carg.size = size;
+    carg.res = NULL;
+
+#ifdef PRINT_TREE
+    print_tree(tree->order, tree->root);
+#endif
+
+    if (!tree->root)
+	return NULL;
+
+    RBT_ASSERT(IS_BLACK(tree->root));
+    RBT_ASSERT(!parent(tree->root));
+
+    rbt_foreach_node(tree, check_node_callback, &carg, 0);
+
+    return carg.res;
+}
+
+static void check_node_callback(RBTNode* x, void* arg)
+{
+    struct check_arg_t* a = (struct check_arg_t*) arg;
+    ErtsFreeSegDesc* seg;
+
+    if (IS_RED(x)) {
+        RBT_ASSERT(IS_BLACK(x->right));
+        RBT_ASSERT(IS_BLACK(x->left));
+    }
+
+    RBT_ASSERT(parent(x) || x == a->tree->root);
+
+    if (x->left) {
+        RBT_ASSERT(cmp_nodes(a->tree->order, x->left, x) < 0);
+    }
+    if (x->right) {
+        RBT_ASSERT(cmp_nodes(a->tree->order, x->right, x) > 0);
+    }
+
+    seg = node_to_desc(a->tree->order, x);
+    RBT_ASSERT(seg->start < seg->end);
+    if (a->size && (seg->end - seg->start) >= a->size) {
+        if (!a->res || cmp_nodes(a->tree->order, x, a->res) < 0) {
+            a->res = x;
+        }
+    }
+    if (a->tree->order == ADDR_ORDER) {
+        RBT_ASSERT(!a->prev_seg || a->prev_seg->end < seg->start);
+        a->prev_seg = seg;
+    }
+}
+
+#endif /* HARD_DEBUG */
+
+
+#ifdef PRINT_TREE
+#define INDENT_STEP 2
+
+#include <stdio.h>
+
+static void
+print_tree_aux(enum SortOrder order, RBTNode *x, int indent)
+{
+    int i;
+
+    if (x) {
+        ErtsFreeSegDesc* desc = node_to_desc(order, x);
+	print_tree_aux(order, x->right, indent + INDENT_STEP);
+	for (i = 0; i < indent; i++) {
+	    putc(' ', stderr);
+	}
+	fprintf(stderr, "%s: sz=%lx [%p - %p] desc=%p\r\n",
+		IS_BLACK(x) ? "BLACK" : "RED",
+                desc->end - desc->start, desc->start, desc->end, desc);
+	print_tree_aux(order, x->left,  indent + INDENT_STEP);
+    }
+}
+
+
+static void
+print_tree(enum SortOrder order, RBTNode* root)
+{
+    fprintf(stderr, " --- %s ordered tree begin ---\r\n", sort_order_names[order]);
+    print_tree_aux(order, root, 0);
+    fprintf(stderr, " --- %s ordered tree end ---\r\n", sort_order_names[order]);
+}
+
+#endif /* PRINT_TREE */
+
+
+#ifdef FREE_SEG_API_SMOKE_TEST
+
+void test_it(void)
+{
+    ErtsFreeSegMap map;
+    ErtsFreeSegDesc *desc, *under, *over, *d1, *d2;
+    const int i = 1; /* reverse addr order */
+
+    {
+        init_free_seg_map(&map, SZ_REVERSE_ADDR_ORDER);
+
+        insert_free_seg(&map, alloc_desc(), (char*)0x11000, (char*)0x12000);
+        HARD_CHECK_TREE(&map.atree, 0); HARD_CHECK_TREE(&map.stree, 0);
+        insert_free_seg(&map, alloc_desc(), (char*)0x13000, (char*)0x14000);
+        HARD_CHECK_TREE(&map.atree, 0); HARD_CHECK_TREE(&map.stree, 0);
+        insert_free_seg(&map, alloc_desc(), (char*)0x15000, (char*)0x17000);
+        HARD_CHECK_TREE(&map.atree, 0); HARD_CHECK_TREE(&map.stree, 0);
+        insert_free_seg(&map, alloc_desc(), (char*)0x8000, (char*)0x10000);
+        HARD_CHECK_TREE(&map.atree, 0); HARD_CHECK_TREE(&map.stree, 0);
+
+        desc = lookup_free_seg(&map, 0x500);
+        ERTS_ASSERT(desc->start == (char*)(i?0x13000L:0x11000L));
+
+        desc = lookup_free_seg(&map, 0x1500);
+        ERTS_ASSERT(desc->start == (char*)0x15000);
+
+        adjacent_free_seg(&map, (char*)0x6666, (char*)0x7777, &under, &over);
+        ERTS_ASSERT(!under && !over);
+
+        adjacent_free_seg(&map, (char*)0x6666, (char*)0x8000, &under, &over);
+        ERTS_ASSERT(!under && over->start == (char*)0x8000);
+
+        adjacent_free_seg(&map, (char*)0x10000, (char*)0x10500, &under, &over);
+        ERTS_ASSERT(under->end == (char*)0x10000 && !over);
+
+        adjacent_free_seg(&map, (char*)0x10100, (char*)0x10500, &under, &over);
+        ERTS_ASSERT(!under && !over);
+
+        adjacent_free_seg(&map, (char*)0x10100, (char*)0x11000, &under, &over);
+        ERTS_ASSERT(!under && over && over->start == (char*)0x11000);
+
+        adjacent_free_seg(&map, (char*)0x12000, (char*)0x12500, &under, &over);
+        ERTS_ASSERT(under && under->end == (char*)0x12000 && !over);
+
+        adjacent_free_seg(&map, (char*)0x12000, (char*)0x13000, &under, &over);
+        ERTS_ASSERT(under && under->end == (char*)0x12000 &&
+                    over && over->start == (char*)0x13000);
+
+        adjacent_free_seg(&map, (char*)0x12500, (char*)0x13000, &under, &over);
+        ERTS_ASSERT(!under && over && over->start == (char*)0x13000);
+
+        d1 = lookup_free_seg(&map, 0x500);
+        ERTS_ASSERT(d1->start == (char*)(i?0x13000L:0x11000L));
+
+        resize_free_seg(&map, d1, d1->start - 0x800, (char*)d1->end);
+        HARD_CHECK_TREE(&map.atree, 0); HARD_CHECK_TREE(&map.stree, 0);
+
+        d2 = lookup_free_seg(&map, 0x1200);
+        ERTS_ASSERT(d2 == d1);
+
+        delete_free_seg(&map, d1);
+        HARD_CHECK_TREE(&map.atree, 0); HARD_CHECK_TREE(&map.stree, 0);
+
+        d1 = lookup_free_seg(&map, 0x1200);
+        ERTS_ASSERT(d1->start == (char*)0x15000);
+    }
+}
+
+#endif /* FREE_SEG_API_SMOKE_TEST */
+
+
+#ifdef HARD_DEBUG_MSEG
+
+/*
+ * Debug stuff used by erl_mseg to check that it does the right thing.
+ * The reason for keeping it here is that we (ab)use the rb-tree code
+ * for keeping track of *allocated* segments.
+ */
+
+typedef struct ErtsFreeSegDesc_fake_ {
+    /*RBTNode snode;    Save memory by skipping unused size tree node */
+    RBTNode anode;      /* node in 'atree' */
+    union {
+        char* start;
+        struct ErtsFreeSegDesc_fake_* next_free;
+    }u;
+    char* end;
+}ErtsFreeSegDesc_fake;
+
+static ErtsFreeSegDesc_fake hard_dbg_mseg_desc_pool[10000];
+static ErtsFreeSegDesc_fake* hard_dbg_mseg_desc_first;
+RBTree hard_dbg_mseg_tree;
+
+static erts_mtx_t hard_dbg_mseg_mtx;
+
+static void hard_dbg_mseg_init(void)
+{
+    ErtsFreeSegDesc_fake* p;
+
+    erts_mtx_init(&hard_dbg_mseg_mtx, "hard_dbg_mseg");
+    hard_dbg_mseg_tree.root = NULL;
+    hard_dbg_mseg_tree.order = ADDR_ORDER;
+
+    p = &hard_dbg_mseg_desc_pool[(sizeof(hard_dbg_mseg_desc_pool) /
+                                  sizeof(*hard_dbg_mseg_desc_pool)) - 1];
+    p->u.next_free = NULL;
+    while (--p >= hard_dbg_mseg_desc_pool) {
+        p->u.next_free = (p+1);
+    }
+    hard_dbg_mseg_desc_first = &hard_dbg_mseg_desc_pool[0];
+}
+
+static ErtsFreeSegDesc* hard_dbg_alloc_desc(void)
+{
+    ErtsFreeSegDesc_fake* p = hard_dbg_mseg_desc_first;
+    ERTS_ASSERT(p || !"HARD_DEBUG_MSEG: Out of mseg descriptors");
+    hard_dbg_mseg_desc_first = p->u.next_free;
+
+    /* Creative pointer arithmetic to return something that looks like
+     * a ErtsFreeSegDesc as long as we don't use the absent 'snode'.
+     */
+    return (ErtsFreeSegDesc*) ((char*)p - offsetof(ErtsFreeSegDesc,anode));
+}
+
+static void hard_dbg_free_desc(ErtsFreeSegDesc* desc)
+{
+    ErtsFreeSegDesc_fake* p = (ErtsFreeSegDesc_fake*) &desc->anode;
+    memset(p, 0xfe, sizeof(*p));
+    p->u.next_free = hard_dbg_mseg_desc_first;
+    hard_dbg_mseg_desc_first = p;
+}
+
+static void check_seg_writable(void* seg, UWord sz)
+{
+    UWord* seg_end = (UWord*)((char*)seg + sz);
+    volatile UWord* p;
+    ERTS_ASSERT(ERTS_IS_PAGEALIGNED(seg));
+    ERTS_ASSERT(ERTS_IS_PAGEALIGNED(sz));
+    for (p=(UWord*)seg; p<seg_end; p += (ERTS_INV_PAGEALIGNED_MASK+1)/sizeof(UWord)) {
+        UWord write_back = *p;
+        *p = 0xfade2b1acc;
+        *p = write_back;
+    }
+}
+
+void hard_dbg_insert_mseg(void* seg, UWord sz)
+{
+    check_seg_writable(seg, sz);
+    erts_mtx_lock(&hard_dbg_mseg_mtx);
+    {
+        ErtsFreeSegDesc *desc = hard_dbg_alloc_desc();
+        RBTNode *prev, *next;
+        desc->start = (char*)seg;
+        desc->end = desc->start + sz - 1; /* -1 to allow adjacent segments in tree */
+        rbt_insert(&hard_dbg_mseg_tree, &desc->anode);
+        prev = rbt_prev_node(&desc->anode);
+        next = rbt_next_node(&desc->anode);
+        ERTS_ASSERT(!prev || anode_to_desc(prev)->end < desc->start);
+        ERTS_ASSERT(!next || anode_to_desc(next)->start > desc->end);
+    }
+    erts_mtx_unlock(&hard_dbg_mseg_mtx);
+}
+
+static ErtsFreeSegDesc* hard_dbg_lookup_seg_at(RBTree* tree, char* start)
+{
+    RBTNode* x = tree->root;
+
+    while (x) {
+        ErtsFreeSegDesc* desc = anode_to_desc(x);
+	if (start < desc->start) {
+            x = x->left;
+	}
+        else if (start > desc->start) {
+            ERTS_ASSERT(start > desc->end);
+            x = x->right;
+        }
+	else
+            return desc;
+    }
+    return NULL;
+}
+
+void hard_dbg_remove_mseg(void* seg, UWord sz)
+{
+    check_seg_writable(seg, sz);
+    erts_mtx_lock(&hard_dbg_mseg_mtx);
+    {
+        ErtsFreeSegDesc* desc = hard_dbg_lookup_seg_at(&hard_dbg_mseg_tree, (char*)seg);
+        ERTS_ASSERT(desc);
+        ERTS_ASSERT(desc->start == (char*)seg);
+        ERTS_ASSERT(desc->end == (char*)seg + sz - 1);
+
+        rbt_delete(&hard_dbg_mseg_tree, &desc->anode);
+        hard_dbg_free_desc(desc);
+    }
+    erts_mtx_unlock(&hard_dbg_mseg_mtx);
+}
+
+#endif /* HARD_DEBUG_MSEG */