]> nv-tegra.nvidia Code Review - linux-3.10.git/blobdiff - mm/oom_kill.c
mm: memcg: only check anon swapin page charges for swap cache
[linux-3.10.git] / mm / oom_kill.c
index 62a5cec08a1752acbce54ebfc69ecd51ebfb8ef0..198600861638b9833ef6603198f980bf2b9fe67f 100644 (file)
 #include <linux/timex.h>
 #include <linux/jiffies.h>
 #include <linux/cpuset.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/notifier.h>
 #include <linux/memcontrol.h>
 #include <linux/mempolicy.h>
 #include <linux/security.h>
 #include <linux/ptrace.h>
+#include <linux/freezer.h>
+#include <linux/ftrace.h>
+#include <linux/ratelimit.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/oom.h>
 
 int sysctl_panic_on_oom;
 int sysctl_oom_kill_allocating_task;
 int sysctl_oom_dump_tasks = 1;
 static DEFINE_SPINLOCK(zone_scan_lock);
 
+/*
+ * compare_swap_oom_score_adj() - compare and swap current's oom_score_adj
+ * @old_val: old oom_score_adj for compare
+ * @new_val: new oom_score_adj for swap
+ *
+ * Sets the oom_score_adj value for current to @new_val iff its present value is
+ * @old_val.  Usually used to reinstate a previous value to prevent racing with
+ * userspacing tuning the value in the interim.
+ */
+void compare_swap_oom_score_adj(int old_val, int new_val)
+{
+       struct sighand_struct *sighand = current->sighand;
+
+       spin_lock_irq(&sighand->siglock);
+       if (current->signal->oom_score_adj == old_val)
+               current->signal->oom_score_adj = new_val;
+       trace_oom_score_adj_update(current);
+       spin_unlock_irq(&sighand->siglock);
+}
+
+/**
+ * test_set_oom_score_adj() - set current's oom_score_adj and return old value
+ * @new_val: new oom_score_adj value
+ *
+ * Sets the oom_score_adj value for current to @new_val with proper
+ * synchronization and returns the old value.  Usually used to temporarily
+ * set a value, save the old value in the caller, and then reinstate it later.
+ */
+int test_set_oom_score_adj(int new_val)
+{
+       struct sighand_struct *sighand = current->sighand;
+       int old_val;
+
+       spin_lock_irq(&sighand->siglock);
+       old_val = current->signal->oom_score_adj;
+       current->signal->oom_score_adj = new_val;
+       trace_oom_score_adj_update(current);
+       spin_unlock_irq(&sighand->siglock);
+
+       return old_val;
+}
+
 #ifdef CONFIG_NUMA
 /**
  * has_intersects_mems_allowed() - check task eligiblity for kill
@@ -83,24 +131,6 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk,
 }
 #endif /* CONFIG_NUMA */
 
-/*
- * If this is a system OOM (not a memcg OOM) and the task selected to be
- * killed is not already running at high (RT) priorities, speed up the
- * recovery by boosting the dying task to the lowest FIFO priority.
- * That helps with the recovery and avoids interfering with RT tasks.
- */
-static void boost_dying_task_prio(struct task_struct *p,
-                                 struct mem_cgroup *mem)
-{
-       struct sched_param param = { .sched_priority = 1 };
-
-       if (mem)
-               return;
-
-       if (!rt_task(p))
-               sched_setscheduler_nocheck(p, SCHED_FIFO, &param);
-}
-
 /*
  * The process p may have detached its own ->mm while exiting or through
  * use_mm(), but one or more of its subthreads may still have a valid
@@ -123,7 +153,7 @@ struct task_struct *find_lock_task_mm(struct task_struct *p)
 
 /* return true if the task is not adequate as candidate victim task. */
 static bool oom_unkillable_task(struct task_struct *p,
-               const struct mem_cgroup *mem, const nodemask_t *nodemask)
+               const struct mem_cgroup *memcg, const nodemask_t *nodemask)
 {
        if (is_global_init(p))
                return true;
@@ -131,7 +161,7 @@ static bool oom_unkillable_task(struct task_struct *p,
                return true;
 
        /* When mem_cgroup_out_of_memory() and p is not member of the group */
-       if (mem && !task_in_mem_cgroup(p, mem))
+       if (memcg && !task_in_mem_cgroup(p, memcg))
                return true;
 
        /* p may not have freeable memory in nodemask */
@@ -150,50 +180,31 @@ static bool oom_unkillable_task(struct task_struct *p,
  * predictable as possible.  The goal is to return the highest value for the
  * task consuming the most memory to avoid subsequent oom failures.
  */
-unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
-                     const nodemask_t *nodemask, unsigned long totalpages)
+unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
+                         const nodemask_t *nodemask, unsigned long totalpages)
 {
-       int points;
+       long points;
+       long adj;
 
-       if (oom_unkillable_task(p, mem, nodemask))
+       if (oom_unkillable_task(p, memcg, nodemask))
                return 0;
 
        p = find_lock_task_mm(p);
        if (!p)
                return 0;
 
-       /*
-        * Shortcut check for a thread sharing p->mm that is OOM_SCORE_ADJ_MIN
-        * so the entire heuristic doesn't need to be executed for something
-        * that cannot be killed.
-        */
-       if (atomic_read(&p->mm->oom_disable_count)) {
+       adj = p->signal->oom_score_adj;
+       if (adj == OOM_SCORE_ADJ_MIN) {
                task_unlock(p);
                return 0;
        }
 
-       /*
-        * When the PF_OOM_ORIGIN bit is set, it indicates the task should have
-        * priority for oom killing.
-        */
-       if (p->flags & PF_OOM_ORIGIN) {
-               task_unlock(p);
-               return 1000;
-       }
-
-       /*
-        * The memory controller may have a limit of 0 bytes, so avoid a divide
-        * by zero, if necessary.
-        */
-       if (!totalpages)
-               totalpages = 1;
-
        /*
         * The baseline for the badness score is the proportion of RAM that each
-        * task's rss and swap space use.
+        * task's rss, pagetable and swap space use.
         */
-       points = (get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS)) * 1000 /
-                       totalpages;
+       points = get_mm_rss(p->mm) + p->mm->nr_ptes +
+                get_mm_counter(p->mm, MM_SWAPENTS);
        task_unlock(p);
 
        /*
@@ -201,23 +212,17 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
         * implementation used by LSMs.
         */
        if (has_capability_noaudit(p, CAP_SYS_ADMIN))
-               points -= 30;
+               adj -= 30;
 
-       /*
-        * /proc/pid/oom_score_adj ranges from -1000 to +1000 such that it may
-        * either completely disable oom killing or always prefer a certain
-        * task.
-        */
-       points += p->signal->oom_score_adj;
+       /* Normalize to oom_score_adj units */
+       adj *= totalpages / 1000;
+       points += adj;
 
        /*
-        * Never return 0 for an eligible task that may be killed since it's
-        * possible that no single user task uses more than 0.1% of memory and
-        * no single admin tasks uses more than 3.0%.
+        * Never return 0 for an eligible task regardless of the root bonus and
+        * oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here).
         */
-       if (points <= 0)
-               return 1;
-       return (points < 1000) ? points : 1000;
+       return points > 0 ? points : 1;
 }
 
 /*
@@ -283,96 +288,118 @@ static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
 }
 #endif
 
+enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
+               unsigned long totalpages, const nodemask_t *nodemask,
+               bool force_kill)
+{
+       if (task->exit_state)
+               return OOM_SCAN_CONTINUE;
+       if (oom_unkillable_task(task, NULL, nodemask))
+               return OOM_SCAN_CONTINUE;
+
+       /*
+        * This task already has access to memory reserves and is being killed.
+        * Don't allow any other task to have access to the reserves.
+        */
+       if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
+               if (unlikely(frozen(task)))
+                       __thaw_task(task);
+               if (!force_kill)
+                       return OOM_SCAN_ABORT;
+       }
+       if (!task->mm)
+               return OOM_SCAN_CONTINUE;
+
+       if (task->flags & PF_EXITING) {
+               /*
+                * If task is current and is in the process of releasing memory,
+                * allow the "kill" to set TIF_MEMDIE, which will allow it to
+                * access memory reserves.  Otherwise, it may stall forever.
+                *
+                * The iteration isn't broken here, however, in case other
+                * threads are found to have already been oom killed.
+                */
+               if (task == current)
+                       return OOM_SCAN_SELECT;
+               else if (!force_kill) {
+                       /*
+                        * If this task is not being ptraced on exit, then wait
+                        * for it to finish before killing some other task
+                        * unnecessarily.
+                        */
+                       if (!(task->group_leader->ptrace & PT_TRACE_EXIT))
+                               return OOM_SCAN_ABORT;
+               }
+       }
+       return OOM_SCAN_OK;
+}
+
 /*
  * Simple selection loop. We chose the process with the highest
- * number of 'points'. We expect the caller will lock the tasklist.
+ * number of 'points'.
  *
  * (not docbooked, we don't want this one cluttering up the manual)
  */
 static struct task_struct *select_bad_process(unsigned int *ppoints,
-               unsigned long totalpages, struct mem_cgroup *mem,
-               const nodemask_t *nodemask)
+               unsigned long totalpages, const nodemask_t *nodemask,
+               bool force_kill)
 {
        struct task_struct *g, *p;
        struct task_struct *chosen = NULL;
-       *ppoints = 0;
+       unsigned long chosen_points = 0;
 
+       rcu_read_lock();
        do_each_thread(g, p) {
                unsigned int points;
 
-               if (!p->mm)
-                       continue;
-               if (oom_unkillable_task(p, mem, nodemask))
+               switch (oom_scan_process_thread(p, totalpages, nodemask,
+                                               force_kill)) {
+               case OOM_SCAN_SELECT:
+                       chosen = p;
+                       chosen_points = ULONG_MAX;
+                       /* fall through */
+               case OOM_SCAN_CONTINUE:
                        continue;
-
-               /*
-                * This task already has access to memory reserves and is
-                * being killed. Don't allow any other task access to the
-                * memory reserve.
-                *
-                * Note: this may have a chance of deadlock if it gets
-                * blocked waiting for another task which itself is waiting
-                * for memory. Is there a better alternative?
-                */
-               if (test_tsk_thread_flag(p, TIF_MEMDIE))
+               case OOM_SCAN_ABORT:
+                       rcu_read_unlock();
                        return ERR_PTR(-1UL);
-
-               if (p->flags & PF_EXITING) {
-                       /*
-                        * If p is the current task and is in the process of
-                        * releasing memory, we allow the "kill" to set
-                        * TIF_MEMDIE, which will allow it to gain access to
-                        * memory reserves.  Otherwise, it may stall forever.
-                        *
-                        * The loop isn't broken here, however, in case other
-                        * threads are found to have already been oom killed.
-                        */
-                       if (p == current) {
-                               chosen = p;
-                               *ppoints = 1000;
-                       } else {
-                               /*
-                                * If this task is not being ptraced on exit,
-                                * then wait for it to finish before killing
-                                * some other task unnecessarily.
-                                */
-                               if (!(task_ptrace(p->group_leader) &
-                                                       PT_TRACE_EXIT))
-                                       return ERR_PTR(-1UL);
-                       }
-               }
-
-               points = oom_badness(p, mem, nodemask, totalpages);
-               if (points > *ppoints) {
+               case OOM_SCAN_OK:
+                       break;
+               };
+               points = oom_badness(p, NULL, nodemask, totalpages);
+               if (points > chosen_points) {
                        chosen = p;
-                       *ppoints = points;
+                       chosen_points = points;
                }
        } while_each_thread(g, p);
+       if (chosen)
+               get_task_struct(chosen);
+       rcu_read_unlock();
 
+       *ppoints = chosen_points * 1000 / totalpages;
        return chosen;
 }
 
 /**
  * dump_tasks - dump current memory state of all system tasks
- * @mem: current's memory controller, if constrained
+ * @memcg: current's memory controller, if constrained
  * @nodemask: nodemask passed to page allocator for mempolicy ooms
  *
  * Dumps the current memory state of all eligible tasks.  Tasks not in the same
  * memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes
  * are not shown.
- * State information includes task's pid, uid, tgid, vm size, rss, cpu, oom_adj
- * value, oom_score_adj value, and name.
- *
- * Call with tasklist_lock read-locked.
+ * State information includes task's pid, uid, tgid, vm size, rss, nr_ptes,
+ * swapents, oom_score_adj value, and name.
  */
-static void dump_tasks(const struct mem_cgroup *mem, const nodemask_t *nodemask)
+static void dump_tasks(const struct mem_cgroup *memcg, const nodemask_t *nodemask)
 {
        struct task_struct *p;
        struct task_struct *task;
 
-       pr_info("[ pid ]   uid  tgid total_vm      rss cpu oom_adj oom_score_adj name\n");
+       pr_info("[ pid ]   uid  tgid total_vm      rss nr_ptes swapents oom_score_adj name\n");
+       rcu_read_lock();
        for_each_process(p) {
-               if (oom_unkillable_task(p, mem, nodemask))
+               if (oom_unkillable_task(p, memcg, nodemask))
                        continue;
 
                task = find_lock_task_mm(p);
@@ -385,17 +412,19 @@ static void dump_tasks(const struct mem_cgroup *mem, const nodemask_t *nodemask)
                        continue;
                }
 
-               pr_info("[%5d] %5d %5d %8lu %8lu %3u     %3d         %5d %s\n",
-                       task->pid, task_uid(task), task->tgid,
-                       task->mm->total_vm, get_mm_rss(task->mm),
-                       task_cpu(task), task->signal->oom_adj,
+               pr_info("[%5d] %5d %5d %8lu %8lu %7lu %8lu         %5d %s\n",
+                       task->pid, from_kuid(&init_user_ns, task_uid(task)),
+                       task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
+                       task->mm->nr_ptes,
+                       get_mm_counter(task->mm, MM_SWAPENTS),
                        task->signal->oom_score_adj, task->comm);
                task_unlock(task);
        }
+       rcu_read_unlock();
 }
 
 static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
-                       struct mem_cgroup *mem, const nodemask_t *nodemask)
+                       struct mem_cgroup *memcg, const nodemask_t *nodemask)
 {
        task_lock(current);
        pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
@@ -405,76 +434,29 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
        cpuset_print_task_mems_allowed(current);
        task_unlock(current);
        dump_stack();
-       mem_cgroup_print_oom_info(mem, p);
-       __show_mem(SHOW_MEM_FILTER_NODES);
+       mem_cgroup_print_oom_info(memcg, p);
+       show_mem(SHOW_MEM_FILTER_NODES);
        if (sysctl_oom_dump_tasks)
-               dump_tasks(mem, nodemask);
+               dump_tasks(memcg, nodemask);
 }
 
 #define K(x) ((x) << (PAGE_SHIFT-10))
-static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem)
-{
-       struct task_struct *q;
-       struct mm_struct *mm;
-
-       p = find_lock_task_mm(p);
-       if (!p)
-               return 1;
-
-       /* mm cannot be safely dereferenced after task_unlock(p) */
-       mm = p->mm;
-
-       pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
-               task_pid_nr(p), p->comm, K(p->mm->total_vm),
-               K(get_mm_counter(p->mm, MM_ANONPAGES)),
-               K(get_mm_counter(p->mm, MM_FILEPAGES)));
-       task_unlock(p);
-
-       /*
-        * Kill all processes sharing p->mm in other thread groups, if any.
-        * They don't get access to memory reserves or a higher scheduler
-        * priority, though, to avoid depletion of all memory or task
-        * starvation.  This prevents mm->mmap_sem livelock when an oom killed
-        * task cannot exit because it requires the semaphore and its contended
-        * by another thread trying to allocate memory itself.  That thread will
-        * now get access to memory reserves since it has a pending fatal
-        * signal.
-        */
-       for_each_process(q)
-               if (q->mm == mm && !same_thread_group(q, p)) {
-                       task_lock(q);   /* Protect ->comm from prctl() */
-                       pr_err("Kill process %d (%s) sharing same memory\n",
-                               task_pid_nr(q), q->comm);
-                       task_unlock(q);
-                       force_sig(SIGKILL, q);
-               }
-
-       set_tsk_thread_flag(p, TIF_MEMDIE);
-       force_sig(SIGKILL, p);
-
-       /*
-        * We give our sacrificial lamb high priority and access to
-        * all the memory it needs. That way it should be able to
-        * exit() and clear out its resources quickly...
-        */
-       boost_dying_task_prio(p, mem);
-
-       return 0;
-}
-#undef K
-
-static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
-                           unsigned int points, unsigned long totalpages,
-                           struct mem_cgroup *mem, nodemask_t *nodemask,
-                           const char *message)
+/*
+ * Must be called while holding a reference to p, which will be released upon
+ * returning.
+ */
+void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
+                     unsigned int points, unsigned long totalpages,
+                     struct mem_cgroup *memcg, nodemask_t *nodemask,
+                     const char *message)
 {
        struct task_struct *victim = p;
        struct task_struct *child;
        struct task_struct *t = p;
+       struct mm_struct *mm;
        unsigned int victim_points = 0;
-
-       if (printk_ratelimit())
-               dump_header(p, gfp_mask, order, mem, nodemask);
+       static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
+                                             DEFAULT_RATELIMIT_BURST);
 
        /*
         * If the task is already exiting, don't alarm the sysadmin or kill
@@ -482,10 +464,13 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
         */
        if (p->flags & PF_EXITING) {
                set_tsk_thread_flag(p, TIF_MEMDIE);
-               boost_dying_task_prio(p, mem);
-               return 0;
+               put_task_struct(p);
+               return;
        }
 
+       if (__ratelimit(&oom_rs))
+               dump_header(p, gfp_mask, order, memcg, nodemask);
+
        task_lock(p);
        pr_err("%s: Kill process %d (%s) score %d or sacrifice child\n",
                message, task_pid_nr(p), p->comm, points);
@@ -493,10 +478,11 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 
        /*
         * If any of p's children has a different mm and is eligible for kill,
-        * the one with the highest badness() score is sacrificed for its
+        * the one with the highest oom_badness() score is sacrificed for its
         * parent.  This attempts to lose the minimal amount of work done while
         * still freeing memory.
         */
+       read_lock(&tasklist_lock);
        do {
                list_for_each_entry(child, &t->children, sibling) {
                        unsigned int child_points;
@@ -506,23 +492,72 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
                        /*
                         * oom_badness() returns 0 if the thread is unkillable
                         */
-                       child_points = oom_badness(child, mem, nodemask,
+                       child_points = oom_badness(child, memcg, nodemask,
                                                                totalpages);
                        if (child_points > victim_points) {
+                               put_task_struct(victim);
                                victim = child;
                                victim_points = child_points;
+                               get_task_struct(victim);
                        }
                }
        } while_each_thread(p, t);
+       read_unlock(&tasklist_lock);
+
+       rcu_read_lock();
+       p = find_lock_task_mm(victim);
+       if (!p) {
+               rcu_read_unlock();
+               put_task_struct(victim);
+               return;
+       } else if (victim != p) {
+               get_task_struct(p);
+               put_task_struct(victim);
+               victim = p;
+       }
+
+       /* mm cannot safely be dereferenced after task_unlock(victim) */
+       mm = victim->mm;
+       pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
+               task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
+               K(get_mm_counter(victim->mm, MM_ANONPAGES)),
+               K(get_mm_counter(victim->mm, MM_FILEPAGES)));
+       task_unlock(victim);
+
+       /*
+        * Kill all user processes sharing victim->mm in other thread groups, if
+        * any.  They don't get access to memory reserves, though, to avoid
+        * depletion of all memory.  This prevents mm->mmap_sem livelock when an
+        * oom killed thread cannot exit because it requires the semaphore and
+        * its contended by another thread trying to allocate memory itself.
+        * That thread will now get access to memory reserves since it has a
+        * pending fatal signal.
+        */
+       for_each_process(p)
+               if (p->mm == mm && !same_thread_group(p, victim) &&
+                   !(p->flags & PF_KTHREAD)) {
+                       if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
+                               continue;
+
+                       task_lock(p);   /* Protect ->comm from prctl() */
+                       pr_err("Kill process %d (%s) sharing same memory\n",
+                               task_pid_nr(p), p->comm);
+                       task_unlock(p);
+                       do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
+               }
+       rcu_read_unlock();
 
-       return oom_kill_task(victim, mem);
+       set_tsk_thread_flag(victim, TIF_MEMDIE);
+       do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
+       put_task_struct(victim);
 }
+#undef K
 
 /*
  * Determines whether the kernel must panic because of the panic_on_oom sysctl.
  */
-static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
-                               int order, const nodemask_t *nodemask)
+void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
+                       int order, const nodemask_t *nodemask)
 {
        if (likely(!sysctl_panic_on_oom))
                return;
@@ -535,47 +570,11 @@ static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
                if (constraint != CONSTRAINT_NONE)
                        return;
        }
-       read_lock(&tasklist_lock);
        dump_header(NULL, gfp_mask, order, NULL, nodemask);
-       read_unlock(&tasklist_lock);
        panic("Out of memory: %s panic_on_oom is enabled\n",
                sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
 }
 
-#ifdef CONFIG_CGROUP_MEM_RES_CTLR
-void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
-{
-       unsigned long limit;
-       unsigned int points = 0;
-       struct task_struct *p;
-
-       /*
-        * If current has a pending SIGKILL, then automatically select it.  The
-        * goal is to allow it to allocate so that it may quickly exit and free
-        * its memory.
-        */
-       if (fatal_signal_pending(current)) {
-               set_thread_flag(TIF_MEMDIE);
-               boost_dying_task_prio(current, NULL);
-               return;
-       }
-
-       check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0, NULL);
-       limit = mem_cgroup_get_limit(mem) >> PAGE_SHIFT;
-       read_lock(&tasklist_lock);
-retry:
-       p = select_bad_process(&points, limit, mem, NULL);
-       if (!p || PTR_ERR(p) == -1UL)
-               goto out;
-
-       if (oom_kill_process(p, gfp_mask, 0, points, limit, mem, NULL,
-                               "Memory cgroup out of memory"))
-               goto retry;
-out:
-       read_unlock(&tasklist_lock);
-}
-#endif
-
 static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
 
 int register_oom_notifier(struct notifier_block *nb)
@@ -683,6 +682,7 @@ static void clear_system_oom(void)
  * @gfp_mask: memory allocation flags
  * @order: amount of memory being requested as a power of 2
  * @nodemask: nodemask passed to page allocator
+ * @force_kill: true if a task must be killed, even if others are exiting
  *
  * If we run out of memory, we have the choice between either
  * killing a random task (bad), letting the system crash (worse)
@@ -690,13 +690,13 @@ static void clear_system_oom(void)
  * don't have to be perfect here, we just have to be good.
  */
 void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
-               int order, nodemask_t *nodemask)
+               int order, nodemask_t *nodemask, bool force_kill)
 {
        const nodemask_t *mpol_mask;
        struct task_struct *p;
        unsigned long totalpages;
        unsigned long freed = 0;
-       unsigned int points;
+       unsigned int uninitialized_var(points);
        enum oom_constraint constraint = CONSTRAINT_NONE;
        int killed = 0;
 
@@ -712,7 +712,6 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
         */
        if (fatal_signal_pending(current)) {
                set_thread_flag(TIF_MEMDIE);
-               boost_dying_task_prio(current, NULL);
                return;
        }
 
@@ -725,46 +724,34 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
        mpol_mask = (constraint == CONSTRAINT_MEMORY_POLICY) ? nodemask : NULL;
        check_panic_on_oom(constraint, gfp_mask, order, mpol_mask);
 
-       read_lock(&tasklist_lock);
-       if (sysctl_oom_kill_allocating_task &&
+       if (sysctl_oom_kill_allocating_task && current->mm &&
            !oom_unkillable_task(current, NULL, nodemask) &&
-           current->mm && !atomic_read(&current->mm->oom_disable_count)) {
-               /*
-                * oom_kill_process() needs tasklist_lock held.  If it returns
-                * non-zero, current could not be killed so we must fallback to
-                * the tasklist scan.
-                */
-               if (!oom_kill_process(current, gfp_mask, order, 0, totalpages,
-                               NULL, nodemask,
-                               "Out of memory (oom_kill_allocating_task)"))
-                       goto out;
-       }
-
-retry:
-       p = select_bad_process(&points, totalpages, NULL, mpol_mask);
-       if (PTR_ERR(p) == -1UL)
+           current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
+               get_task_struct(current);
+               oom_kill_process(current, gfp_mask, order, 0, totalpages, NULL,
+                                nodemask,
+                                "Out of memory (oom_kill_allocating_task)");
                goto out;
+       }
 
+       p = select_bad_process(&points, totalpages, mpol_mask, force_kill);
        /* Found nothing?!?! Either we hang forever, or we panic. */
        if (!p) {
                dump_header(NULL, gfp_mask, order, NULL, mpol_mask);
-               read_unlock(&tasklist_lock);
                panic("Out of memory and no killable processes...\n");
        }
-
-       if (oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,
-                               nodemask, "Out of memory"))
-               goto retry;
-       killed = 1;
+       if (PTR_ERR(p) != -1UL) {
+               oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,
+                                nodemask, "Out of memory");
+               killed = 1;
+       }
 out:
-       read_unlock(&tasklist_lock);
-
        /*
-        * Give "p" a good chance of killing itself before we
-        * retry to allocate memory unless "p" is current
+        * Give the killed threads a good chance of exiting before trying to
+        * allocate memory again.
         */
-       if (killed && !test_thread_flag(TIF_MEMDIE))
-               schedule_timeout_uninterruptible(1);
+       if (killed)
+               schedule_timeout_killable(1);
 }
 
 /*
@@ -776,9 +763,8 @@ out:
 void pagefault_out_of_memory(void)
 {
        if (try_set_system_oom()) {
-               out_of_memory(NULL, 0, 0, NULL);
+               out_of_memory(NULL, 0, 0, NULL, false);
                clear_system_oom();
        }
-       if (!test_thread_flag(TIF_MEMDIE))
-               schedule_timeout_uninterruptible(1);
+       schedule_timeout_killable(1);
 }