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Subject[PATCH v1 04/12] powerpc/pseries: CMM: Drop page array
Date
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).

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Richard Fontana <rfontana@redhat.com>
Cc: Allison Randal <allison@lohutok.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arun KS <arunks@codeaurora.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/powerpc/platforms/pseries/cmm.c | 163 ++++++---------------------
1 file changed, 36 insertions(+), 127 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
index 738eb1681d40..33d31e48ec15 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -75,21 +75,13 @@ 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);
@@ -97,8 +89,9 @@ 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;
@@ -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;
@@ -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);
@@ -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);
@@ -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();
@@ -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;
@@ -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);
--
2.21.0
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