mm: memcontrol: zap oom_info_lock

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

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f7c9b4c..36db05f 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1150,12 +1150,9 @@ static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
  */
 void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
 {
-       /* oom_info_lock ensures that parallel ooms do not interleave */
-       static DEFINE_MUTEX(oom_info_lock);
        struct mem_cgroup *iter;
        unsigned int i;
 
-       mutex_lock(&oom_info_lock);
        rcu_read_lock();
 
        if (p) {
@@ -1199,7 +1196,6 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
 
                pr_cont("\n");
        }
-       mutex_unlock(&oom_info_lock);
 }
 
 /*
@@ -1236,7 +1232,7 @@ static unsigned long mem_cgroup_get_limit(struct mem_cgroup *memcg)
        return limit;
 }
 
-static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
+static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
                                     int order)
 {
        struct oom_control oc = {
@@ -1314,6 +1310,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
        }
 unlock:
        mutex_unlock(&oom_lock);
+       return chosen;
 }
 
 #if MAX_NUMNODES > 1
@@ -5029,6 +5026,8 @@ static ssize_t memory_max_write(struct kernfs_open_file *of,
                                char *buf, size_t nbytes, loff_t off)
 {
        struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+       unsigned int nr_reclaims = MEM_CGROUP_RECLAIM_RETRIES;
+       bool drained = false;
        unsigned long max;
        int err;
 
@@ -5037,9 +5036,36 @@ static ssize_t memory_max_write(struct kernfs_open_file *of,
        if (err)
                return err;
 
-       err = mem_cgroup_resize_limit(memcg, max);
-       if (err)
-               return err;
+       xchg(&memcg->memory.limit, max);
+
+       for (;;) {
+               unsigned long nr_pages = page_counter_read(&memcg->memory);
+
+               if (nr_pages <= max)
+                       break;
+
+               if (signal_pending(current)) {
+                       err = -EINTR;
+                       break;
+               }
+
+               if (!drained) {
+                       drain_all_stock(memcg);
+                       drained = true;
+                       continue;
+               }
+
+               if (nr_reclaims) {
+                       if (!try_to_free_mem_cgroup_pages(memcg, nr_pages - max,
+                                                         GFP_KERNEL, true))
+                               nr_reclaims--;
+                       continue;
+               }
+
+               mem_cgroup_events(memcg, MEMCG_OOM, 1);
+               if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0))
+                       break;
+       }
 
        memcg_wb_domain_size_changed(memcg);
        return nbytes;
@@ -5390,6 +5416,10 @@ static void uncharge_list(struct list_head *page_list)
        struct list_head *next;
        struct page *page;
 
+       /*
+        * Note that the list can be a single page->lru; hence the
+        * do-while loop instead of a simple list_for_each_entry().
+        */
        next = page_list->next;
        do {
                unsigned int nr_pages = 1;