Commit 74e2498c authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google) Committed by Steven Rostedt (Google)
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mm/memblock: Add reserved memory release function 



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: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: default avatarMike 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: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 5f3719f6

include/linux/mm.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

mm/memblock.c

+54 −12
Original line number Diff line number Diff line
@@ -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
@@ -2309,21 +2326,46 @@ 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;

}

	}

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;

}

EXPORT_SYMBOL_GPL(reserve_mem_find_by_name);



/*

 * Parse reserve_mem=nn:align:name