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powerpc/pseries/cmm: Drop page array
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We can simply store the pages in a list (page->lru), no need for a
separate data structure (+ complicated handling). This is how most
other balloon drivers store allocated pages without additional
tracking data.

For the notifiers, use page_to_pfn() to check if a page is in the
applicable range. Use page_to_phys() in plpar_page_set_loaned() and
plpar_page_set_active() (I assume due to the __pa() that's the right
thing to do).

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191031142933.10779-5-david@redhat.com
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David Hildenbrand authored and Michael Ellerman committed Nov 13, 2019
1 parent 68f7a04 commit 4a1745c
Showing 1 changed file with 36 additions and 127 deletions.
163 changes: 36 additions & 127 deletions arch/powerpc/platforms/pseries/cmm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -75,30 +75,23 @@ module_param_named(debug, cmm_debug, uint, 0644);
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 LIST_HEAD(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;

static long plpar_page_set_loaned(unsigned long vpa)
static long plpar_page_set_loaned(struct page *page)
{
const unsigned long vpa = page_to_phys(page);
unsigned long cmo_page_sz = cmo_get_page_size();
long rc = 0;
int i;
Expand All @@ -113,8 +106,9 @@ static long plpar_page_set_loaned(unsigned long vpa)
return rc;
}

static long plpar_page_set_active(unsigned long vpa)
static long plpar_page_set_active(struct page *page)
{
const unsigned long vpa = page_to_phys(page);
unsigned long cmo_page_sz = cmo_get_page_size();
long rc = 0;
int i;
Expand All @@ -138,8 +132,7 @@ static long plpar_page_set_active(unsigned long vpa)
**/
static long cmm_alloc_pages(long nr)
{
struct cmm_page_array *pa, *npa;
unsigned long addr;
struct page *page;
long rc;

cmm_dbg("Begin request for %ld pages\n", nr);
Expand All @@ -156,43 +149,20 @@ static long cmm_alloc_pages(long nr)
break;
}

addr = __get_free_page(GFP_NOIO | __GFP_NOWARN |
__GFP_NORETRY | __GFP_NOMEMALLOC);
if (!addr)
page = alloc_page(GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY |
__GFP_NOMEMALLOC);
if (!page)
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)))) {
rc = plpar_page_set_loaned(page);
if (rc) {
pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc);
spin_unlock(&cmm_lock);
free_page(addr);
__free_page(page);
break;
}

pa->page[pa->index++] = addr;
list_add(&page->lru, &cmm_page_list);
loaned_pages++;
totalram_pages_dec();
spin_unlock(&cmm_lock);
Expand All @@ -212,25 +182,16 @@ static long cmm_alloc_pages(long nr)
**/
static long cmm_free_pages(long nr)
{
struct cmm_page_array *pa;
unsigned long addr;
struct page *page, *tmp;

cmm_dbg("Begin free of %ld pages.\n", nr);
spin_lock(&cmm_lock);
pa = cmm_page_list;
while (nr) {
if (!pa || pa->index <= 0)
list_for_each_entry_safe(page, tmp, &cmm_page_list, lru) {
if (!nr)
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);
plpar_page_set_active(page);
list_del(&page->lru);
__free_page(page);
loaned_pages--;
nr--;
totalram_pages_inc();
Expand Down Expand Up @@ -496,20 +457,13 @@ static struct notifier_block cmm_reboot_nb = {
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;
struct page *page;

spin_lock(&cmm_lock);
pa = cmm_page_list;
while (pa) {
if ((unsigned long)pa >= start && (unsigned long)pa < end)
list_for_each_entry(page, &cmm_page_list, lru) {
if (page_to_pfn(page) >= marg->start_pfn &&
page_to_pfn(page) < marg->start_pfn + marg->nr_pages)
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;
Expand Down Expand Up @@ -550,69 +504,24 @@ static struct notifier_block cmm_mem_isolate_nb = {
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;
struct page *page, *tmp;
unsigned long freed = 0;

cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n",
start_page, marg->nr_pages);
cmm_dbg("Memory going offline, searching PFN 0x%lx (%ld pages).\n",
marg->start_pfn, 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_inc();
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;
list_for_each_entry_safe(page, tmp, &cmm_page_list, lru) {
if (page_to_pfn(page) < marg->start_pfn ||
page_to_pfn(page) >= marg->start_pfn + marg->nr_pages)
continue;
plpar_page_set_active(page);
list_del(&page->lru);
__free_page(page);
freed++;
loaned_pages--;
totalram_pages_inc();
}

spin_unlock(&cmm_lock);
Expand Down

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