From: Masami Hiramatsu (Google) <mhira...@kernel.org>
Add reserve_mem_release_by_name() to release a reserved memory region
with a given name. This allows us to release reserved memory which is
defined by kernel cmdline, after boot.
Signed-off-by: Masami Hiramatsu (Google) <mhira...@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <r...@kernel.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: linux...@kvack.org
---
Changes in v4:
- Use free_reserved_area() according to Mike's comment.
Changes in v2:
- Rename reserved_mem_* to reserve_mem_*.
---
include/linux/mm.h | 1 +
mm/memblock.c | 66 +++++++++++++++++++++++++++++++++++++++++++---------
2 files changed, 55 insertions(+), 12 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7b1068ddcbb7..1ee9e7447485 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4123,6 +4123,7 @@ void vma_pgtable_walk_begin(struct vm_area_struct *vma);
void vma_pgtable_walk_end(struct vm_area_struct *vma);
int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t
*size);
+int reserve_mem_release_by_name(const char *name);
#ifdef CONFIG_64BIT
int do_mseal(unsigned long start, size_t len_in, unsigned long flags);
diff --git a/mm/memblock.c b/mm/memblock.c
index 95af35fd1389..8cd95f60015d 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -16,6 +16,7 @@
#include <linux/kmemleak.h>
#include <linux/seq_file.h>
#include <linux/memblock.h>
+#include <linux/mutex.h>
#include <asm/sections.h>
#include <linux/io.h>
@@ -2283,6 +2284,7 @@ struct reserve_mem_table {
};
static struct reserve_mem_table reserved_mem_table[RESERVE_MEM_MAX_ENTRIES];
static int reserved_mem_count;
+static DEFINE_MUTEX(reserve_mem_lock);
/* Add wildcard region with a lookup name */
static void __init reserved_mem_add(phys_addr_t start, phys_addr_t size,
@@ -2296,6 +2298,21 @@ static void __init reserved_mem_add(phys_addr_t start,
phys_addr_t size,
strscpy(map->name, name);
}
+static struct reserve_mem_table *reserve_mem_find_by_name_nolock(const char
*name)
+{
+ struct reserve_mem_table *map;
+ int i;
+
+ for (i = 0; i < reserved_mem_count; i++) {
+ map = &reserved_mem_table[i];
+ if (!map->size)
+ continue;
+ if (strcmp(name, map->name) == 0)
+ return map;
+ }
+ return NULL;
+}
+
/**
* reserve_mem_find_by_name - Find reserved memory region with a given name
* @name: The name that is attached to a reserved memory region
@@ -2309,22 +2326,47 @@ static void __init reserved_mem_add(phys_addr_t start,
phys_addr_t size,
int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t
*size)
{
struct reserve_mem_table *map;
- int i;
- for (i = 0; i < reserved_mem_count; i++) {
- map = &reserved_mem_table[i];
- if (!map->size)
- continue;
- if (strcmp(name, map->name) == 0) {
- *start = map->start;
- *size = map->size;
- return 1;
- }
- }
- return 0;
+ guard(mutex)(&reserve_mem_lock);
+ map = reserve_mem_find_by_name_nolock(name);
+ if (!map)
+ return 0;
+
+ *start = map->start;
+ *size = map->size;
+ return 1;
}
EXPORT_SYMBOL_GPL(reserve_mem_find_by_name);
+/**
+ * reserve_mem_release_by_name - Release reserved memory region with a given
name
+ * @name: The name that is attatched to a reserved memory region
+ *
+ * Forcibly release the pages in the reserved memory region so that those
memory
+ * can be used as free memory. After released the reserved region size becomes
0.
+ *
+ * Returns: 1 if released or 0 if not found.
+ */
+int reserve_mem_release_by_name(const char *name)
+{
+ char buf[RESERVE_MEM_NAME_SIZE + 12];
+ struct reserve_mem_table *map;
+ void *start, *end;
+
+ guard(mutex)(&reserve_mem_lock);
+ map = reserve_mem_find_by_name_nolock(name);
+ if (!map)
+ return 0;
+
+ start = phys_to_virt(map->start);
+ end = start + map->size - 1;
+ snprintf(buf, sizeof(buf), "reserve_mem:%s", name);
+ free_reserved_area(start, end, 0, buf);
+ map->size = 0;
+
+ return 1;
+}
+
/*
* Parse reserve_mem=nn:align:name
*/
