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mm/memblock: Add reserved memory release function

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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) <mhiramat@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-mm@kvack.org
Link: https://lore.kernel.org/173989133862.230693.14094993331347437600.stgit@devnote2
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu (Google) 2025-02-19 00:08:58 +09:00 committed by Steven Rostedt (Google)
parent 5f3719f697
commit 74e2498ccf
2 changed files with 55 additions and 12 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
include/linux/mm.h
View file

@ -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);

60
mm/memblock.c
View file

@ -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) {
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;
}
}
return 0;
}
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
*/