diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 1488816588ea5b2f46c3638af30e5b3236a336d7..d060fce4940ed7a4989ad1ec9dc8e432a1b3c316 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -20,6 +20,8 @@
#include "linux/namei.h"
#include "linux/proc_fs.h"
#include "linux/syscalls.h"
+#include "linux/list.h"
+#include "linux/mm.h"
#include "linux/console.h"
#include "asm/irq.h"
#include "asm/uaccess.h"
@@ -347,6 +349,142 @@ static struct mc_device *mconsole_find_dev(char *name)
return(NULL);
}
+#define UNPLUGGED_PER_PAGE \
+ ((PAGE_SIZE - sizeof(struct list_head)) / sizeof(unsigned long))
+
+struct unplugged_pages {
+ struct list_head list;
+ void *pages[UNPLUGGED_PER_PAGE];
+};
+
+static unsigned long long unplugged_pages_count = 0;
+static struct list_head unplugged_pages = LIST_HEAD_INIT(unplugged_pages);
+static int unplug_index = UNPLUGGED_PER_PAGE;
+
+static int mem_config(char *str)
+{
+ unsigned long long diff;
+ int err = -EINVAL, i, add;
+ char *ret;
+
+ if(str[0] != '=')
+ goto out;
+
+ str++;
+ if(str[0] == '-')
+ add = 0;
+ else if(str[0] == '+'){
+ add = 1;
+ }
+ else goto out;
+
+ str++;
+ diff = memparse(str, &ret);
+ if(*ret != '\0')
+ goto out;
+
+ diff /= PAGE_SIZE;
+
+ for(i = 0; i < diff; i++){
+ struct unplugged_pages *unplugged;
+ void *addr;
+
+ if(add){
+ if(list_empty(&unplugged_pages))
+ break;
+
+ unplugged = list_entry(unplugged_pages.next,
+ struct unplugged_pages, list);
+ if(unplug_index > 0)
+ addr = unplugged->pages[--unplug_index];
+ else {
+ list_del(&unplugged->list);
+ addr = unplugged;
+ unplug_index = UNPLUGGED_PER_PAGE;
+ }
+
+ free_page((unsigned long) addr);
+ unplugged_pages_count--;
+ }
+ else {
+ struct page *page;
+
+ page = alloc_page(GFP_ATOMIC);
+ if(page == NULL)
+ break;
+
+ unplugged = page_address(page);
+ if(unplug_index == UNPLUGGED_PER_PAGE){
+ INIT_LIST_HEAD(&unplugged->list);
+ list_add(&unplugged->list, &unplugged_pages);
+ unplug_index = 0;
+ }
+ else {
+ struct list_head *entry = unplugged_pages.next;
+ addr = unplugged;
+
+ unplugged = list_entry(entry,
+ struct unplugged_pages,
+ list);
+ unplugged->pages[unplug_index++] = addr;
+ err = os_drop_memory(addr, PAGE_SIZE);
+ if(err)
+ printk("Failed to release memory - "
+ "errno = %d\n", err);
+ }
+
+ unplugged_pages_count++;
+ }
+ }
+
+ err = 0;
+out:
+ return err;
+}
+
+static int mem_get_config(char *name, char *str, int size, char **error_out)
+{
+ char buf[sizeof("18446744073709551615")];
+ int len = 0;
+
+ sprintf(buf, "%ld", uml_physmem);
+ CONFIG_CHUNK(str, size, len, buf, 1);
+
+ return len;
+}
+
+static int mem_id(char **str, int *start_out, int *end_out)
+{
+ *start_out = 0;
+ *end_out = 0;
+
+ return 0;
+}
+
+static int mem_remove(int n)
+{
+ return -EBUSY;
+}
+
+static struct mc_device mem_mc = {
+ .name = "mem",
+ .config = mem_config,
+ .get_config = mem_get_config,
+ .id = mem_id,
+ .remove = mem_remove,
+};
+
+static int mem_mc_init(void)
+{
+ if(can_drop_memory())
+ mconsole_register_dev(&mem_mc);
+ else printk("Can't release memory to the host - memory hotplug won't "
+ "be supported\n");
+ return 0;
+}
+
+__initcall(mem_mc_init);
+
#define CONFIG_BUF_SIZE 64
static void mconsole_get_config(int (*get_config)(char *, char *, int,
diff --git a/arch/um/include/mem_user.h b/arch/um/include/mem_user.h
index a1064c5823bfe92c8e5c83c71592e37ceacd5e69..a54514d2cc3ab81aa9e4244bb9f36f99f622a5b5 100644
--- a/arch/um/include/mem_user.h
+++ b/arch/um/include/mem_user.h
@@ -49,7 +49,6 @@ extern int iomem_size;
extern unsigned long host_task_size;
extern unsigned long task_size;
-extern void check_devanon(void);
extern int init_mem_user(void);
extern void setup_memory(void *entry);
extern unsigned long find_iomem(char *driver, unsigned long *len_out);
diff --git a/arch/um/include/os.h b/arch/um/include/os.h
index d3d1bc6074ef465c41bf17f21f9bf6e6ef4fe74b..5fb84e889b2b618d66455c299df413ffb60a8b83 100644
--- a/arch/um/include/os.h
+++ b/arch/um/include/os.h
@@ -205,6 +205,8 @@ extern int os_map_memory(void *virt, int fd, unsigned long long off,
extern int os_protect_memory(void *addr, unsigned long len,
int r, int w, int x);
extern int os_unmap_memory(void *addr, int len);
+extern int os_drop_memory(void *addr, int length);
+extern int can_drop_memory(void);
extern void os_flush_stdout(void);
/* tt.c
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 9d7d69a523bb551f069898bed0f2f2be7c4ef247..6ab372da96579e4a49e372b920ff302d703484f2 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -121,36 +121,11 @@ int create_tmp_file(unsigned long long len)
return(fd);
}
-static int create_anon_file(unsigned long long len)
-{
- void *addr;
- int fd;
-
- fd = open("/dev/anon", O_RDWR);
- if(fd < 0) {
- perror("opening /dev/anon");
- exit(1);
- }
-
- addr = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
- if(addr == MAP_FAILED){
- perror("mapping physmem file");
- exit(1);
- }
- munmap(addr, len);
-
- return(fd);
-}
-
-extern int have_devanon;
-
int create_mem_file(unsigned long long len)
{
int err, fd;
- if(have_devanon)
- fd = create_anon_file(len);
- else fd = create_tmp_file(len);
+ fd = create_tmp_file(len);
err = os_set_exec_close(fd, 1);
if(err < 0){
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index d261888f39c439493f1e2071ed4c98ba07b350ef..8176b0b52047061ae681e19d51583f4e683cad97 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -11,6 +11,7 @@
#include <linux/unistd.h>
#include <sys/mman.h>
#include <sys/wait.h>
+#include <sys/mman.h>
#include "ptrace_user.h"
#include "os.h"
#include "user.h"
@@ -20,6 +21,7 @@
#include "kern_util.h"
#include "longjmp.h"
#include "skas_ptrace.h"
+#include "kern_constants.h"
#define ARBITRARY_ADDR -1
#define FAILURE_PID -1
@@ -187,6 +189,48 @@ int os_unmap_memory(void *addr, int len)
return(0);
}
+#ifndef MADV_REMOVE
+#define MADV_REMOVE 0x5 /* remove these pages & resources */
+#endif
+
+int os_drop_memory(void *addr, int length)
+{
+ int err;
+
+ err = madvise(addr, length, MADV_REMOVE);
+ if(err < 0)
+ err = -errno;
+ return err;
+}
+
+int can_drop_memory(void)
+{
+ void *addr;
+ int fd;
+
+ printk("Checking host MADV_REMOVE support...");
+ fd = create_mem_file(UM_KERN_PAGE_SIZE);
+ if(fd < 0){
+ printk("Creating test memory file failed, err = %d\n", -fd);
+ return 0;
+ }
+
+ addr = mmap64(NULL, UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE, fd, 0);
+ if(addr == MAP_FAILED){
+ printk("Mapping test memory file failed, err = %d\n", -errno);
+ return 0;
+ }
+
+ if(madvise(addr, UM_KERN_PAGE_SIZE, MADV_REMOVE) != 0){
+ printk("MADV_REMOVE failed, err = %d\n", -errno);
+ return 0;
+ }
+
+ printk("OK\n");
+ return 1;
+}
+
void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int))
{
int flags = 0, pages;
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index 32753131f8d847789a11fc365097274d8093fd74..387e26af301a57c6ca0a861c654727af7a5b3696 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -470,25 +470,6 @@ int can_do_skas(void)
}
#endif
-int have_devanon = 0;
-
-/* Runs on boot kernel stack - already safe to use printk. */
-
-void check_devanon(void)
-{
- int fd;
-
- printk("Checking for /dev/anon on the host...");
- fd = open("/dev/anon", O_RDWR);
- if(fd < 0){
- printk("Not available (open failed with errno %d)\n", errno);
- return;
- }
-
- printk("OK\n");
- have_devanon = 1;
-}
-
int __init parse_iomem(char *str, int *add)
{
struct iomem_region *new;
@@ -664,6 +645,5 @@ void os_check_bugs(void)
{
check_ptrace();
check_sigio();
- check_devanon();
}