proc: convert to kstrto*()/kstrto*_from_user()

[cascardo/linux.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1742a2d..6ddaeba 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -441,6 +441,34 @@ struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page)
        return &memcg->css;
 }
 
+/**
+ * page_cgroup_ino - return inode number of the memcg a page is charged to
+ * @page: the page
+ *
+ * Look up the closest online ancestor of the memory cgroup @page is charged to
+ * and return its inode number or 0 if @page is not charged to any cgroup. It
+ * is safe to call this function without holding a reference to @page.
+ *
+ * Note, this function is inherently racy, because there is nothing to prevent
+ * the cgroup inode from getting torn down and potentially reallocated a moment
+ * after page_cgroup_ino() returns, so it only should be used by callers that
+ * do not care (such as procfs interfaces).
+ */
+ino_t page_cgroup_ino(struct page *page)
+{
+       struct mem_cgroup *memcg;
+       unsigned long ino = 0;
+
+       rcu_read_lock();
+       memcg = READ_ONCE(page->mem_cgroup);
+       while (memcg && !(memcg->css.flags & CSS_ONLINE))
+               memcg = parent_mem_cgroup(memcg);
+       if (memcg)
+               ino = cgroup_ino(memcg->css.cgroup);
+       rcu_read_unlock();
+       return ino;
+}
+
 static struct mem_cgroup_per_zone *
 mem_cgroup_page_zoneinfo(struct mem_cgroup *memcg, struct page *page)
 {
@@ -2071,40 +2099,6 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
        css_put_many(&memcg->css, nr_pages);
 }
 
-/*
- * try_get_mem_cgroup_from_page - look up page's memcg association
- * @page: the page
- *
- * Look up, get a css reference, and return the memcg that owns @page.
- *
- * The page must be locked to prevent racing with swap-in and page
- * cache charges.  If coming from an unlocked page table, the caller
- * must ensure the page is on the LRU or this can race with charging.
- */
-struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
-{
-       struct mem_cgroup *memcg;
-       unsigned short id;
-       swp_entry_t ent;
-
-       VM_BUG_ON_PAGE(!PageLocked(page), page);
-
-       memcg = page->mem_cgroup;
-       if (memcg) {
-               if (!css_tryget_online(&memcg->css))
-                       memcg = NULL;
-       } else if (PageSwapCache(page)) {
-               ent.val = page_private(page);
-               id = lookup_swap_cgroup_id(ent);
-               rcu_read_lock();
-               memcg = mem_cgroup_from_id(id);
-               if (memcg && !css_tryget_online(&memcg->css))
-                       memcg = NULL;
-               rcu_read_unlock();
-       }
-       return memcg;
-}
-
 static void lock_page_lru(struct page *page, int *isolated)
 {
        struct zone *zone = page_zone(page);
@@ -5301,8 +5295,20 @@ int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
                 * the page lock, which serializes swap cache removal, which
                 * in turn serializes uncharging.
                 */
+               VM_BUG_ON_PAGE(!PageLocked(page), page);
                if (page->mem_cgroup)
                        goto out;
+
+               if (do_swap_account) {
+                       swp_entry_t ent = { .val = page_private(page), };
+                       unsigned short id = lookup_swap_cgroup_id(ent);
+
+                       rcu_read_lock();
+                       memcg = mem_cgroup_from_id(id);
+                       if (memcg && !css_tryget_online(&memcg->css))
+                               memcg = NULL;
+                       rcu_read_unlock();
+               }
        }
 
        if (PageTransHuge(page)) {
@@ -5310,8 +5316,6 @@ int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
                VM_BUG_ON_PAGE(!PageTransHuge(page), page);
        }
 
-       if (do_swap_account && PageSwapCache(page))
-               memcg = try_get_mem_cgroup_from_page(page);
        if (!memcg)
                memcg = get_mem_cgroup_from_mm(mm);