NFS: checking for NULL instead of IS_ERR() in nfs_commit_file()

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

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 36db05f..fe787f5 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -207,6 +207,7 @@ static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
 /* "mc" and its members are protected by cgroup_mutex */
 static struct move_charge_struct {
        spinlock_t        lock; /* for from, to */
+       struct mm_struct  *mm;
        struct mem_cgroup *from;
        struct mem_cgroup *to;
        unsigned long flags;
@@ -4667,6 +4668,8 @@ static void __mem_cgroup_clear_mc(void)
 
 static void mem_cgroup_clear_mc(void)
 {
+       struct mm_struct *mm = mc.mm;
+
        /*
         * we must clear moving_task before waking up waiters at the end of
         * task migration.
@@ -4676,7 +4679,10 @@ static void mem_cgroup_clear_mc(void)
        spin_lock(&mc.lock);
        mc.from = NULL;
        mc.to = NULL;
+       mc.mm = NULL;
        spin_unlock(&mc.lock);
+
+       mmput(mm);
 }
 
 static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
@@ -4733,6 +4739,7 @@ static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
                VM_BUG_ON(mc.moved_swap);
 
                spin_lock(&mc.lock);
+               mc.mm = mm;
                mc.from = from;
                mc.to = memcg;
                mc.flags = move_flags;
@@ -4742,8 +4749,9 @@ static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
                ret = mem_cgroup_precharge_mc(mm);
                if (ret)
                        mem_cgroup_clear_mc();
+       } else {
+               mmput(mm);
        }
-       mmput(mm);
        return ret;
 }
 
@@ -4852,11 +4860,11 @@ put:                    /* get_mctgt_type() gets the page */
        return ret;
 }
 
-static void mem_cgroup_move_charge(struct mm_struct *mm)
+static void mem_cgroup_move_charge(void)
 {
        struct mm_walk mem_cgroup_move_charge_walk = {
                .pmd_entry = mem_cgroup_move_charge_pte_range,
-               .mm = mm,
+               .mm = mc.mm,
        };
 
        lru_add_drain_all();
@@ -4868,7 +4876,7 @@ static void mem_cgroup_move_charge(struct mm_struct *mm)
        atomic_inc(&mc.from->moving_account);
        synchronize_rcu();
 retry:
-       if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
+       if (unlikely(!down_read_trylock(&mc.mm->mmap_sem))) {
                /*
                 * Someone who are holding the mmap_sem might be waiting in
                 * waitq. So we cancel all extra charges, wake up all waiters,
@@ -4885,23 +4893,16 @@ retry:
         * additional charge, the page walk just aborts.
         */
        walk_page_range(0, ~0UL, &mem_cgroup_move_charge_walk);
-       up_read(&mm->mmap_sem);
+       up_read(&mc.mm->mmap_sem);
        atomic_dec(&mc.from->moving_account);
 }
 
-static void mem_cgroup_move_task(struct cgroup_taskset *tset)
+static void mem_cgroup_move_task(void)
 {
-       struct cgroup_subsys_state *css;
-       struct task_struct *p = cgroup_taskset_first(tset, &css);
-       struct mm_struct *mm = get_task_mm(p);
-
-       if (mm) {
-               if (mc.to)
-                       mem_cgroup_move_charge(mm);
-               mmput(mm);
-       }
-       if (mc.to)
+       if (mc.to) {
+               mem_cgroup_move_charge();
                mem_cgroup_clear_mc();
+       }
 }
 #else  /* !CONFIG_MMU */
 static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
@@ -4911,7 +4912,7 @@ static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
 static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
 {
 }
-static void mem_cgroup_move_task(struct cgroup_taskset *tset)
+static void mem_cgroup_move_task(void)
 {
 }
 #endif
@@ -5195,7 +5196,7 @@ struct cgroup_subsys memory_cgrp_subsys = {
        .css_reset = mem_cgroup_css_reset,
        .can_attach = mem_cgroup_can_attach,
        .cancel_attach = mem_cgroup_cancel_attach,
-       .attach = mem_cgroup_move_task,
+       .post_attach = mem_cgroup_move_task,
        .bind = mem_cgroup_bind,
        .dfl_cftypes = memory_files,
        .legacy_cftypes = mem_cgroup_legacy_files,