6 files changed, 30 insertions, 52 deletions

diff --git a/include/linux/oom.h b/include/linux/oom.h
index 922dab164eb0..da60007075b5 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -29,8 +29,23 @@ enum oom_scan_t {
         OOM_SCAN_SELECT,        /* always select this thread first */
 };
 
-extern void compare_swap_oom_score_adj(short old_val, short new_val);
-extern short test_set_oom_score_adj(short new_val);
+/* Thread is the potential origin of an oom condition; kill first on oom */
+#define OOM_FLAG_ORIGIN         ((__force oom_flags_t)0x1)
+
+static inline void set_current_oom_origin(void)
+{
+        current->signal->oom_flags |= OOM_FLAG_ORIGIN;
+}
+
+static inline void clear_current_oom_origin(void)
+{
+        current->signal->oom_flags &= ~OOM_FLAG_ORIGIN;
+}
+
+static inline bool oom_task_origin(const struct task_struct *p)
+{
+        return !!(p->signal->oom_flags & OOM_FLAG_ORIGIN);
+}
 
 extern unsigned long oom_badness(struct task_struct *p,
                 struct mem_cgroup *memcg, const nodemask_t *nodemask,
diff --git a/include/linux/sched.h b/include/linux/sched.h
index ed30456152da..3e387df065fc 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -631,6 +631,7 @@ struct signal_struct {
         struct rw_semaphore group_rwsem;
 #endif
 
+        oom_flags_t oom_flags;
         short oom_score_adj;            /* OOM kill score adjustment */
         short oom_score_adj_min;        /* OOM kill score adjustment min value.
                                          * Only settable by CAP_SYS_RESOURCE. */
diff --git a/include/linux/types.h b/include/linux/types.h
index 1cc0e4b9a048..4d118ba11349 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -156,6 +156,7 @@ typedef u32 dma_addr_t;
 #endif
 typedef unsigned __bitwise__ gfp_t;
 typedef unsigned __bitwise__ fmode_t;
+typedef unsigned __bitwise__ oom_flags_t;
 
 #ifdef CONFIG_PHYS_ADDR_T_64BIT
 typedef u64 phys_addr_t;
diff --git a/mm/ksm.c b/mm/ksm.c
index b4d5a9deb17f..382d930a0bf1 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1919,12 +1919,9 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr,
         if (ksm_run != flags) {
                 ksm_run = flags;
                 if (flags & KSM_RUN_UNMERGE) {
-                        short oom_score_adj;
-
-                        oom_score_adj = test_set_oom_score_adj(OOM_SCORE_ADJ_MAX);
+                        set_current_oom_origin();
                         err = unmerge_and_remove_all_rmap_items();
-                        compare_swap_oom_score_adj(OOM_SCORE_ADJ_MAX,
-                                                                oom_score_adj);
+                        clear_current_oom_origin();
                         if (err) {
                                 ksm_run = KSM_RUN_STOP;
                                 count = err;
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 37ab4c5ab6e8..18f1ae2b45de 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -44,48 +44,6 @@ 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(short old_val, short 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.
- */
-short test_set_oom_score_adj(short 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
@@ -310,6 +268,13 @@ enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
         if (!task->mm)
                 return OOM_SCAN_CONTINUE;
 
+        /*
+         * If task is allocating a lot of memory and has been marked to be
+         * killed first if it triggers an oom, then select it.
+         */
+        if (oom_task_origin(task))
+                return OOM_SCAN_SELECT;
+
         if (task->flags & PF_EXITING && !force_kill) {
                 /*
                  * If this task is not being ptraced on exit, then wait for it
diff --git a/mm/swapfile.c b/mm/swapfile.c
index bb6f6a04e92d..e97a0e5aea91 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1498,7 +1498,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
         struct address_space *mapping;
         struct inode *inode;
         struct filename *pathname;
-        short oom_score_adj;
         int i, type, prev;
         int err;
 
@@ -1557,9 +1556,9 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
         p->flags &= ~SWP_WRITEOK;
         spin_unlock(&swap_lock);
 
-        oom_score_adj = test_set_oom_score_adj(OOM_SCORE_ADJ_MAX);
+        set_current_oom_origin();
         err = try_to_unuse(type, false, 0); /* force all pages to be unused */
-        compare_swap_oom_score_adj(OOM_SCORE_ADJ_MAX, oom_score_adj);
+        clear_current_oom_origin();
 
         if (err) {
                 /* re-insert swap space back into swap_list */