1 files changed, 73 insertions, 25 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index db76ef726293..da53a252b259 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -612,8 +612,10 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
         /* pagein of a big page is an event. So, ignore page size */
         if (nr_pages > 0)
                 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGIN_COUNT]);
-        else
+        else {
                 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGOUT_COUNT]);
+                nr_pages = -nr_pages; /* for event */
+        }
 
         __this_cpu_add(mem->stat->count[MEM_CGROUP_EVENTS], nr_pages);
 
@@ -1111,6 +1113,23 @@ static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
         return false;
 }
 
+/**
+ * mem_cgroup_check_margin - check if the memory cgroup allows charging
+ * @mem: memory cgroup to check
+ * @bytes: the number of bytes the caller intends to charge
+ *
+ * Returns a boolean value on whether @mem can be charged @bytes or
+ * whether this would exceed the limit.
+ */
+static bool mem_cgroup_check_margin(struct mem_cgroup *mem, unsigned long bytes)
+{
+        if (!res_counter_check_margin(&mem->res, bytes))
+                return false;
+        if (do_swap_account && !res_counter_check_margin(&mem->memsw, bytes))
+                return false;
+        return true;
+}
+
 static unsigned int get_swappiness(struct mem_cgroup *memcg)
 {
         struct cgroup *cgrp = memcg->css.cgroup;
@@ -1832,27 +1851,39 @@ static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
                 if (likely(!ret))
                         return CHARGE_OK;
 
+                res_counter_uncharge(&mem->res, csize);
                 mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
                 flags |= MEM_CGROUP_RECLAIM_NOSWAP;
         } else
                 mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
-
-        if (csize > PAGE_SIZE) /* change csize and retry */
+        /*
+         * csize can be either a huge page (HPAGE_SIZE), a batch of
+         * regular pages (CHARGE_SIZE), or a single regular page
+         * (PAGE_SIZE).
+         *
+         * Never reclaim on behalf of optional batching, retry with a
+         * single page instead.
+         */
+        if (csize == CHARGE_SIZE)
                 return CHARGE_RETRY;
 
         if (!(gfp_mask & __GFP_WAIT))
                 return CHARGE_WOULDBLOCK;
 
         ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
-                                        gfp_mask, flags);
+                                              gfp_mask, flags);
+        if (mem_cgroup_check_margin(mem_over_limit, csize))
+                return CHARGE_RETRY;
         /*
-         * try_to_free_mem_cgroup_pages() might not give us a full
-         * picture of reclaim. Some pages are reclaimed and might be
-         * moved to swap cache or just unmapped from the cgroup.
-         * Check the limit again to see if the reclaim reduced the
-         * current usage of the cgroup before giving up
+         * Even though the limit is exceeded at this point, reclaim
+         * may have been able to free some pages.  Retry the charge
+         * before killing the task.
+         *
+         * Only for regular pages, though: huge pages are rather
+         * unlikely to succeed so close to the limit, and we fall back
+         * to regular pages anyway in case of failure.
          */
-        if (ret || mem_cgroup_check_under_limit(mem_over_limit))
+        if (csize == PAGE_SIZE && ret)
                 return CHARGE_RETRY;
 
         /*
@@ -2144,6 +2175,8 @@ void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail)
         struct page_cgroup *tail_pc = lookup_page_cgroup(tail);
         unsigned long flags;
 
+        if (mem_cgroup_disabled())
+                return;
         /*
          * We have no races with charge/uncharge but will have races with
          * page state accounting.
@@ -2233,7 +2266,12 @@ static int mem_cgroup_move_account(struct page_cgroup *pc,
 {
         int ret = -EINVAL;
         unsigned long flags;
-
+        /*
+         * The page is isolated from LRU. So, collapse function
+         * will not handle this page. But page splitting can happen.
+         * Do this check under compound_page_lock(). The caller should
+         * hold it.
+         */
         if ((charge_size > PAGE_SIZE) && !PageTransHuge(pc->page))
                 return -EBUSY;
 
@@ -2265,7 +2303,7 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
         struct cgroup *cg = child->css.cgroup;
         struct cgroup *pcg = cg->parent;
         struct mem_cgroup *parent;
-        int charge = PAGE_SIZE;
+        int page_size = PAGE_SIZE;
         unsigned long flags;
         int ret;
 
@@ -2278,23 +2316,26 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
                 goto out;
         if (isolate_lru_page(page))
                 goto put;
-        /* The page is isolated from LRU and we have no race with splitting */
-        charge = PAGE_SIZE << compound_order(page);
+
+        if (PageTransHuge(page))
+                page_size = HPAGE_SIZE;
 
         parent = mem_cgroup_from_cont(pcg);
-        ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false, charge);
+        ret = __mem_cgroup_try_charge(NULL, gfp_mask,
+                                &parent, false, page_size);
         if (ret || !parent)
                 goto put_back;
 
-        if (charge > PAGE_SIZE)
+        if (page_size > PAGE_SIZE)
                 flags = compound_lock_irqsave(page);
 
-        ret = mem_cgroup_move_account(pc, child, parent, true, charge);
+        ret = mem_cgroup_move_account(pc, child, parent, true, page_size);
         if (ret)
-                mem_cgroup_cancel_charge(parent, charge);
-put_back:
-        if (charge > PAGE_SIZE)
+                mem_cgroup_cancel_charge(parent, page_size);
+
+        if (page_size > PAGE_SIZE)
                 compound_unlock_irqrestore(page, flags);
+put_back:
         putback_lru_page(page);
 put:
         put_page(page);
@@ -2312,13 +2353,19 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
                                 gfp_t gfp_mask, enum charge_type ctype)
 {
         struct mem_cgroup *mem = NULL;
+        int page_size = PAGE_SIZE;
         struct page_cgroup *pc;
+        bool oom = true;
         int ret;
-        int page_size = PAGE_SIZE;
 
         if (PageTransHuge(page)) {
                 page_size <<= compound_order(page);
                 VM_BUG_ON(!PageTransHuge(page));
+                /*
+                 * Never OOM-kill a process for a huge page.  The
+                 * fault handler will fall back to regular pages.
+                 */
+                oom = false;
         }
 
         pc = lookup_page_cgroup(page);
@@ -2327,7 +2374,7 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
                 return 0;
         prefetchw(pc);
 
-        ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true, page_size);
+        ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, oom, page_size);
         if (ret || !mem)
                 return ret;
 
@@ -5013,9 +5060,9 @@ struct cgroup_subsys mem_cgroup_subsys = {
 static int __init enable_swap_account(char *s)
 {
         /* consider enabled if no parameter or 1 is given */
-        if (!s || !strcmp(s, "1"))
+        if (!(*s) || !strcmp(s, "=1"))
                 really_do_swap_account = 1;
-        else if (!strcmp(s, "0"))
+        else if (!strcmp(s, "=0"))
                 really_do_swap_account = 0;
         return 1;
 }
@@ -5023,7 +5070,8 @@ __setup("swapaccount", enable_swap_account);
 
 static int __init disable_swap_account(char *s)
 {
-        enable_swap_account("0");
+        printk_once("noswapaccount is deprecated and will be removed in 2.6.40. Use swapaccount=0 instead\n");
+        enable_swap_account("=0");
         return 1;
 }
 __setup("noswapaccount", disable_swap_account);