blob: 66e7227469b8c279c4ff392be4e9a0ec37c66e8c [file] [log] [blame]
/*
* Collaborative memory management interface.
*
* Copyright (C) 2008 IBM Corporation
* Author(s): Brian King (brking@linux.vnet.ibm.com),
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/gfp.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/oom.h>
#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/stringify.h>
#include <linux/swap.h>
#include <linux/device.h>
#include <asm/firmware.h>
#include <asm/hvcall.h>
#include <asm/mmu.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <linux/memory.h>
#include <asm/plpar_wrappers.h>
#define CMM_DRIVER_VERSION "1.0.0"
#define CMM_DEFAULT_DELAY 1
#define CMM_HOTPLUG_DELAY 5
#define CMM_DEBUG 0
#define CMM_DISABLE 0
#define CMM_OOM_KB 1024
#define CMM_MIN_MEM_MB 256
#define KB2PAGES(_p) ((_p)>>(PAGE_SHIFT-10))
#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
/*
* The priority level tries to ensure that this notifier is called as
* late as possible to reduce thrashing in the shared memory pool.
*/
#define CMM_MEM_HOTPLUG_PRI 1
#define CMM_MEM_ISOLATE_PRI 15
static unsigned int delay = CMM_DEFAULT_DELAY;
static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY;
static unsigned int oom_kb = CMM_OOM_KB;
static unsigned int cmm_debug = CMM_DEBUG;
static unsigned int cmm_disabled = CMM_DISABLE;
static unsigned long min_mem_mb = CMM_MIN_MEM_MB;
static struct device cmm_dev;
MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>");
MODULE_DESCRIPTION("IBM System p Collaborative Memory Manager");
MODULE_LICENSE("GPL");
MODULE_VERSION(CMM_DRIVER_VERSION);
module_param_named(delay, delay, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. "
"[Default=" __stringify(CMM_DEFAULT_DELAY) "]");
module_param_named(hotplug_delay, hotplug_delay, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(delay, "Delay (in seconds) after memory hotplug remove "
"before loaning resumes. "
"[Default=" __stringify(CMM_HOTPLUG_DELAY) "]");
module_param_named(oom_kb, oom_kb, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. "
"[Default=" __stringify(CMM_OOM_KB) "]");
module_param_named(min_mem_mb, min_mem_mb, ulong, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. "
"[Default=" __stringify(CMM_MIN_MEM_MB) "]");
module_param_named(debug, cmm_debug, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. "
"[Default=" __stringify(CMM_DEBUG) "]");
#define CMM_NR_PAGES ((PAGE_SIZE - sizeof(void *) - sizeof(unsigned long)) / sizeof(unsigned long))
#define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); }
struct cmm_page_array {
struct cmm_page_array *next;
unsigned long index;
unsigned long page[CMM_NR_PAGES];
};
static unsigned long loaned_pages;
static unsigned long loaned_pages_target;
static unsigned long oom_freed_pages;
static struct cmm_page_array *cmm_page_list;
static DEFINE_SPINLOCK(cmm_lock);
static DEFINE_MUTEX(hotplug_mutex);
static int hotplug_occurred; /* protected by the hotplug mutex */
static struct task_struct *cmm_thread_ptr;
/**
* cmm_alloc_pages - Allocate pages and mark them as loaned
* @nr: number of pages to allocate
*
* Return value:
* number of pages requested to be allocated which were not
**/
static long cmm_alloc_pages(long nr)
{
struct cmm_page_array *pa, *npa;
unsigned long addr;
long rc;
cmm_dbg("Begin request for %ld pages\n", nr);
while (nr) {
/* Exit if a hotplug operation is in progress or occurred */
if (mutex_trylock(&hotplug_mutex)) {
if (hotplug_occurred) {
mutex_unlock(&hotplug_mutex);
break;
}
mutex_unlock(&hotplug_mutex);
} else {
break;
}
addr = __get_free_page(GFP_NOIO | __GFP_NOWARN |
__GFP_NORETRY | __GFP_NOMEMALLOC);
if (!addr)
break;
spin_lock(&cmm_lock);
pa = cmm_page_list;
if (!pa || pa->index >= CMM_NR_PAGES) {
/* Need a new page for the page list. */
spin_unlock(&cmm_lock);
npa = (struct cmm_page_array *)__get_free_page(
GFP_NOIO | __GFP_NOWARN |
__GFP_NORETRY | __GFP_NOMEMALLOC);
if (!npa) {
pr_info("%s: Can not allocate new page list\n", __func__);
free_page(addr);
break;
}
spin_lock(&cmm_lock);
pa = cmm_page_list;
if (!pa || pa->index >= CMM_NR_PAGES) {
npa->next = pa;
npa->index = 0;
pa = npa;
cmm_page_list = pa;
} else
free_page((unsigned long) npa);
}
if ((rc = plpar_page_set_loaned(__pa(addr)))) {
pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc);
spin_unlock(&cmm_lock);
free_page(addr);
break;
}
pa->page[pa->index++] = addr;
loaned_pages++;
totalram_pages--;
spin_unlock(&cmm_lock);
nr--;
}
cmm_dbg("End request with %ld pages unfulfilled\n", nr);
return nr;
}
/**
* cmm_free_pages - Free pages and mark them as active
* @nr: number of pages to free
*
* Return value:
* number of pages requested to be freed which were not
**/
static long cmm_free_pages(long nr)
{
struct cmm_page_array *pa;
unsigned long addr;
cmm_dbg("Begin free of %ld pages.\n", nr);
spin_lock(&cmm_lock);
pa = cmm_page_list;
while (nr) {
if (!pa || pa->index <= 0)
break;
addr = pa->page[--pa->index];
if (pa->index == 0) {
pa = pa->next;
free_page((unsigned long) cmm_page_list);
cmm_page_list = pa;
}
plpar_page_set_active(__pa(addr));
free_page(addr);
loaned_pages--;
nr--;
totalram_pages++;
}
spin_unlock(&cmm_lock);
cmm_dbg("End request with %ld pages unfulfilled\n", nr);
return nr;
}
/**
* cmm_oom_notify - OOM notifier
* @self: notifier block struct
* @dummy: not used
* @parm: returned - number of pages freed
*
* Return value:
* NOTIFY_OK
**/
static int cmm_oom_notify(struct notifier_block *self,
unsigned long dummy, void *parm)
{
unsigned long *freed = parm;
long nr = KB2PAGES(oom_kb);
cmm_dbg("OOM processing started\n");
nr = cmm_free_pages(nr);
loaned_pages_target = loaned_pages;
*freed += KB2PAGES(oom_kb) - nr;
oom_freed_pages += KB2PAGES(oom_kb) - nr;
cmm_dbg("OOM processing complete\n");
return NOTIFY_OK;
}
/**
* cmm_get_mpp - Read memory performance parameters
*
* Makes hcall to query the current page loan request from the hypervisor.
*
* Return value:
* nothing
**/
static void cmm_get_mpp(void)
{
int rc;
struct hvcall_mpp_data mpp_data;
signed long active_pages_target, page_loan_request, target;
signed long total_pages = totalram_pages + loaned_pages;
signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE;
rc = h_get_mpp(&mpp_data);
if (rc != H_SUCCESS)
return;
page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE);
target = page_loan_request + (signed long)loaned_pages;
if (target < 0 || total_pages < min_mem_pages)
target = 0;
if (target > oom_freed_pages)
target -= oom_freed_pages;
else
target = 0;
active_pages_target = total_pages - target;
if (min_mem_pages > active_pages_target)
target = total_pages - min_mem_pages;
if (target < 0)
target = 0;
loaned_pages_target = target;
cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n",
page_loan_request, loaned_pages, loaned_pages_target,
oom_freed_pages, totalram_pages);
}
static struct notifier_block cmm_oom_nb = {
.notifier_call = cmm_oom_notify
};
/**
* cmm_thread - CMM task thread
* @dummy: not used
*
* Return value:
* 0
**/
static int cmm_thread(void *dummy)
{
unsigned long timeleft;
while (1) {
timeleft = msleep_interruptible(delay * 1000);
if (kthread_should_stop() || timeleft)
break;
if (mutex_trylock(&hotplug_mutex)) {
if (hotplug_occurred) {
hotplug_occurred = 0;
mutex_unlock(&hotplug_mutex);
cmm_dbg("Hotplug operation has occurred, "
"loaning activity suspended "
"for %d seconds.\n",
hotplug_delay);
timeleft = msleep_interruptible(hotplug_delay *
1000);
if (kthread_should_stop() || timeleft)
break;
continue;
}
mutex_unlock(&hotplug_mutex);
} else {
cmm_dbg("Hotplug operation in progress, activity "
"suspended\n");
continue;
}
cmm_get_mpp();
if (loaned_pages_target > loaned_pages) {
if (cmm_alloc_pages(loaned_pages_target - loaned_pages))
loaned_pages_target = loaned_pages;
} else if (loaned_pages_target < loaned_pages)
cmm_free_pages(loaned_pages - loaned_pages_target);
}
return 0;
}
#define CMM_SHOW(name, format, args...) \
static ssize_t show_##name(struct device *dev, \
struct device_attribute *attr, \
char *buf) \
{ \
return sprintf(buf, format, ##args); \
} \
static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));
CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
static ssize_t show_oom_pages(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages));
}
static ssize_t store_oom_pages(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
unsigned long val = simple_strtoul (buf, NULL, 10);
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (val != 0)
return -EBADMSG;
oom_freed_pages = 0;
return count;
}
static DEVICE_ATTR(oom_freed_kb, S_IWUSR | S_IRUGO,
show_oom_pages, store_oom_pages);
static struct device_attribute *cmm_attrs[] = {
&dev_attr_loaned_kb,
&dev_attr_loaned_target_kb,
&dev_attr_oom_freed_kb,
};
static struct bus_type cmm_subsys = {
.name = "cmm",
.dev_name = "cmm",
};
/**
* cmm_sysfs_register - Register with sysfs
*
* Return value:
* 0 on success / other on failure
**/
static int cmm_sysfs_register(struct device *dev)
{
int i, rc;
if ((rc = subsys_system_register(&cmm_subsys, NULL)))
return rc;
dev->id = 0;
dev->bus = &cmm_subsys;
if ((rc = device_register(dev)))
goto subsys_unregister;
for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) {
if ((rc = device_create_file(dev, cmm_attrs[i])))
goto fail;
}
return 0;
fail:
while (--i >= 0)
device_remove_file(dev, cmm_attrs[i]);
device_unregister(dev);
subsys_unregister:
bus_unregister(&cmm_subsys);
return rc;
}
/**
* cmm_unregister_sysfs - Unregister from sysfs
*
**/
static void cmm_unregister_sysfs(struct device *dev)
{
int i;
for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++)
device_remove_file(dev, cmm_attrs[i]);
device_unregister(dev);
bus_unregister(&cmm_subsys);
}
/**
* cmm_reboot_notifier - Make sure pages are not still marked as "loaned"
*
**/
static int cmm_reboot_notifier(struct notifier_block *nb,
unsigned long action, void *unused)
{
if (action == SYS_RESTART) {
if (cmm_thread_ptr)
kthread_stop(cmm_thread_ptr);
cmm_thread_ptr = NULL;
cmm_free_pages(loaned_pages);
}
return NOTIFY_DONE;
}
static struct notifier_block cmm_reboot_nb = {
.notifier_call = cmm_reboot_notifier,
};
/**
* cmm_count_pages - Count the number of pages loaned in a particular range.
*
* @arg: memory_isolate_notify structure with address range and count
*
* Return value:
* 0 on success
**/
static unsigned long cmm_count_pages(void *arg)
{
struct memory_isolate_notify *marg = arg;
struct cmm_page_array *pa;
unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn);
unsigned long end = start + (marg->nr_pages << PAGE_SHIFT);
unsigned long idx;
spin_lock(&cmm_lock);
pa = cmm_page_list;
while (pa) {
if ((unsigned long)pa >= start && (unsigned long)pa < end)
marg->pages_found++;
for (idx = 0; idx < pa->index; idx++)
if (pa->page[idx] >= start && pa->page[idx] < end)
marg->pages_found++;
pa = pa->next;
}
spin_unlock(&cmm_lock);
return 0;
}
/**
* cmm_memory_isolate_cb - Handle memory isolation notifier calls
* @self: notifier block struct
* @action: action to take
* @arg: struct memory_isolate_notify data for handler
*
* Return value:
* NOTIFY_OK or notifier error based on subfunction return value
**/
static int cmm_memory_isolate_cb(struct notifier_block *self,
unsigned long action, void *arg)
{
int ret = 0;
if (action == MEM_ISOLATE_COUNT)
ret = cmm_count_pages(arg);
return notifier_from_errno(ret);
}
static struct notifier_block cmm_mem_isolate_nb = {
.notifier_call = cmm_memory_isolate_cb,
.priority = CMM_MEM_ISOLATE_PRI
};
/**
* cmm_mem_going_offline - Unloan pages where memory is to be removed
* @arg: memory_notify structure with page range to be offlined
*
* Return value:
* 0 on success
**/
static int cmm_mem_going_offline(void *arg)
{
struct memory_notify *marg = arg;
unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn);
unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT);
struct cmm_page_array *pa_curr, *pa_last, *npa;
unsigned long idx;
unsigned long freed = 0;
cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n",
start_page, marg->nr_pages);
spin_lock(&cmm_lock);
/* Search the page list for pages in the range to be offlined */
pa_last = pa_curr = cmm_page_list;
while (pa_curr) {
for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) {
if ((pa_curr->page[idx] < start_page) ||
(pa_curr->page[idx] >= end_page))
continue;
plpar_page_set_active(__pa(pa_curr->page[idx]));
free_page(pa_curr->page[idx]);
freed++;
loaned_pages--;
totalram_pages++;
pa_curr->page[idx] = pa_last->page[--pa_last->index];
if (pa_last->index == 0) {
if (pa_curr == pa_last)
pa_curr = pa_last->next;
pa_last = pa_last->next;
free_page((unsigned long)cmm_page_list);
cmm_page_list = pa_last;
}
}
pa_curr = pa_curr->next;
}
/* Search for page list structures in the range to be offlined */
pa_last = NULL;
pa_curr = cmm_page_list;
while (pa_curr) {
if (((unsigned long)pa_curr >= start_page) &&
((unsigned long)pa_curr < end_page)) {
npa = (struct cmm_page_array *)__get_free_page(
GFP_NOIO | __GFP_NOWARN |
__GFP_NORETRY | __GFP_NOMEMALLOC);
if (!npa) {
spin_unlock(&cmm_lock);
cmm_dbg("Failed to allocate memory for list "
"management. Memory hotplug "
"failed.\n");
return -ENOMEM;
}
memcpy(npa, pa_curr, PAGE_SIZE);
if (pa_curr == cmm_page_list)
cmm_page_list = npa;
if (pa_last)
pa_last->next = npa;
free_page((unsigned long) pa_curr);
freed++;
pa_curr = npa;
}
pa_last = pa_curr;
pa_curr = pa_curr->next;
}
spin_unlock(&cmm_lock);
cmm_dbg("Released %ld pages in the search range.\n", freed);
return 0;
}
/**
* cmm_memory_cb - Handle memory hotplug notifier calls
* @self: notifier block struct
* @action: action to take
* @arg: struct memory_notify data for handler
*
* Return value:
* NOTIFY_OK or notifier error based on subfunction return value
*
**/
static int cmm_memory_cb(struct notifier_block *self,
unsigned long action, void *arg)
{
int ret = 0;
switch (action) {
case MEM_GOING_OFFLINE:
mutex_lock(&hotplug_mutex);
hotplug_occurred = 1;
ret = cmm_mem_going_offline(arg);
break;
case MEM_OFFLINE:
case MEM_CANCEL_OFFLINE:
mutex_unlock(&hotplug_mutex);
cmm_dbg("Memory offline operation complete.\n");
break;
case MEM_GOING_ONLINE:
case MEM_ONLINE:
case MEM_CANCEL_ONLINE:
break;
}
return notifier_from_errno(ret);
}
static struct notifier_block cmm_mem_nb = {
.notifier_call = cmm_memory_cb,
.priority = CMM_MEM_HOTPLUG_PRI
};
/**
* cmm_init - Module initialization
*
* Return value:
* 0 on success / other on failure
**/
static int cmm_init(void)
{
int rc = -ENOMEM;
if (!firmware_has_feature(FW_FEATURE_CMO))
return -EOPNOTSUPP;
if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0)
return rc;
if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
goto out_oom_notifier;
if ((rc = cmm_sysfs_register(&cmm_dev)))
goto out_reboot_notifier;
if (register_memory_notifier(&cmm_mem_nb) ||
register_memory_isolate_notifier(&cmm_mem_isolate_nb))
goto out_unregister_notifier;
if (cmm_disabled)
return rc;
cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
if (IS_ERR(cmm_thread_ptr)) {
rc = PTR_ERR(cmm_thread_ptr);
goto out_unregister_notifier;
}
return rc;
out_unregister_notifier:
unregister_memory_notifier(&cmm_mem_nb);
unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
cmm_unregister_sysfs(&cmm_dev);
out_reboot_notifier:
unregister_reboot_notifier(&cmm_reboot_nb);
out_oom_notifier:
unregister_oom_notifier(&cmm_oom_nb);
return rc;
}
/**
* cmm_exit - Module exit
*
* Return value:
* nothing
**/
static void cmm_exit(void)
{
if (cmm_thread_ptr)
kthread_stop(cmm_thread_ptr);
unregister_oom_notifier(&cmm_oom_nb);
unregister_reboot_notifier(&cmm_reboot_nb);
unregister_memory_notifier(&cmm_mem_nb);
unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
cmm_free_pages(loaned_pages);
cmm_unregister_sysfs(&cmm_dev);
}
/**
* cmm_set_disable - Disable/Enable CMM
*
* Return value:
* 0 on success / other on failure
**/
static int cmm_set_disable(const char *val, struct kernel_param *kp)
{
int disable = simple_strtoul(val, NULL, 10);
if (disable != 0 && disable != 1)
return -EINVAL;
if (disable && !cmm_disabled) {
if (cmm_thread_ptr)
kthread_stop(cmm_thread_ptr);
cmm_thread_ptr = NULL;
cmm_free_pages(loaned_pages);
} else if (!disable && cmm_disabled) {
cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
if (IS_ERR(cmm_thread_ptr))
return PTR_ERR(cmm_thread_ptr);
}
cmm_disabled = disable;
return 0;
}
module_param_call(disable, cmm_set_disable, param_get_uint,
&cmm_disabled, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
"[Default=" __stringify(CMM_DISABLE) "]");
module_init(cmm_init);
module_exit(cmm_exit);