[PATCH 1/7] debug/mem: add utility to name anonymous memory mappings

[John Snow <jsnow@redhat.com>]

Add support to name mmap'd memory regions using
PR_SET_VMA_ANON_NAME. On supported platforms, the QEMU utility
functions are no-ops.

This is useful primarily for debugging and profiling QEMU; beind able
to see and correlate each VMA segment with a specific use within QEMU.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 include/qemu/mmap-vma.h | 18 +++++++++++
 util/mmap-vma.c         | 67 +++++++++++++++++++++++++++++++++++++++++
 util/meson.build        |  1 +
 3 files changed, 86 insertions(+)
 create mode 100644 include/qemu/mmap-vma.h
 create mode 100644 util/mmap-vma.c

diff --git a/include/qemu/mmap-vma.h b/include/qemu/mmap-vma.h
new file mode 100644
index 00000000000..763ea5a5cab
--- /dev/null
+++ b/include/qemu/mmap-vma.h
@@ -0,0 +1,18 @@
+/*
+ * Utility for naming VMA allocations in linux
+ *
+ * Copyright (c) Red Hat, Inc 2026
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#ifndef __QEMU_MMAP_VMA_H
+#define __QEMU_MMAP_VMA_H
+
+#include <stddef.h>
+#include "osdep.h"
+
+int qemu_name_vma(void *ptr, size_t sz, const char *fmt, ...)
+    G_GNUC_PRINTF(3, 4);
+
+#endif
diff --git a/util/mmap-vma.c b/util/mmap-vma.c
new file mode 100644
index 00000000000..7dcef3b7455
--- /dev/null
+++ b/util/mmap-vma.c
@@ -0,0 +1,67 @@
+/*
+ * Utility for naming VMA allocations in linux
+ *
+ * Copyright (c) Red Hat, Inc 2026
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+#include "qemu/mmap-vma.h"
+#include "qemu/osdep.h"
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+
+#if defined(__linux__)
+#include <sys/prctl.h>
+#endif
+
+#define VMA_PREFIX " qemu: "
+#define VMA_MAXLEN 80
+
+/*
+ * Give a human-readable name to a previously mmap'd memory segment.
+ * This feature is only available on Linux >= 5.17, and only when the
+ * kernel was configured with CONFIG_ANON_VMA_NAME=y.
+ *
+ * For systems without this option, prctl() will return -1 and set
+ * errno to EINVAL, and can be safely ignored.
+ *
+ * For systems with this option, these human-readable names will be
+ * visible in /proc/$pid/[s]maps, pmap output, etc.
+ */
+G_GNUC_PRINTF(3, 0)
+static int qemu_vname_vma(void *ptr, size_t sz, const char *fmt, va_list args)
+{
+    int rc = 0;
+
+#if defined(PR_SET_VMA_ANON_NAME)
+    char strbuf[VMA_MAXLEN];
+
+    assert(sizeof(VMA_PREFIX) < sizeof(strbuf));
+    strncpy(strbuf, VMA_PREFIX, sizeof(strbuf));
+    rc = vsnprintf(strbuf + sizeof(VMA_PREFIX),
+                   sizeof(strbuf) - sizeof(VMA_PREFIX), fmt, args);
+    if (rc < 0) {
+        return -errno;
+    } else if (rc >= (sizeof(strbuf) - sizeof(VMA_PREFIX))) {
+        sprintf(strbuf + sizeof(strbuf) - 4, "...");
+    }
+
+    rc = prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, sz, strbuf);
+    if (rc) {
+        return -errno;
+    }
+#endif
+
+    return rc;
+}
+
+G_GNUC_PRINTF(3, 4)
+int qemu_name_vma(void *ptr, size_t sz, const char *fmt, ...)
+{
+    va_list args;
+
+    va_start(args, fmt);
+    return qemu_vname_vma(ptr, sz, fmt, args);
+}
diff --git a/util/meson.build b/util/meson.build
index fa174c07a57..861ee228d5b 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -1,5 +1,6 @@
 util_ss.add(files('osdep.c', 'cutils.c', 'unicode.c', 'qemu-timer-common.c'))
 util_ss.add(files('thread-context.c'), numa)
+util_ss.add(files('mmap-vma.c'))
 if host_os != 'windows'
   util_ss.add(files('aio-posix.c'))
   util_ss.add(files('fdmon-poll.c'))
-- 
2.56.0