linux 2.6.16.38 w/ vs2.0.3-rc1

[linux-2.6.git] / mm / oom_kill.c

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index f9c115a..f2479c9 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -46,26 +46,15 @@
 unsigned long badness(struct task_struct *p, unsigned long uptime)
 {
        unsigned long points, cpu_time, run_time, s;
-       struct mm_struct *mm;
-       struct task_struct *child;
+       struct list_head *tsk;
 
-       task_lock(p);
-       mm = p->mm;
-       if (!mm) {
-               task_unlock(p);
+       if (!p->mm)
                return 0;
-       }
 
        /*
         * The memory size of the process is the basis for the badness.
         */
-       points = mm->total_vm;
-
-       /*
-        * After this unlock we can no longer dereference local variable `mm'
-        */
-       task_unlock(p);
-
+       points = p->mm->total_vm;
        /* FIXME: add vserver badness ;) */
 
        /*
@@ -76,11 +65,11 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
         * child is eating the vast majority of memory, adding only half
         * to the parents will make the child our kill candidate of choice.
         */
-       list_for_each_entry(child, &p->children, sibling) {
-               task_lock(child);
-               if (child->mm != mm && child->mm)
-                       points += child->mm->total_vm/2 + 1;
-               task_unlock(child);
+       list_for_each(tsk, &p->children) {
+               struct task_struct *chld;
+               chld = list_entry(tsk, struct task_struct, sibling);
+               if (chld->mm != p->mm && chld->mm)
+                       points += chld->mm->total_vm/2 + 1;
        }
 
        /*
@@ -256,24 +245,17 @@ static void __oom_kill_task(task_t *p, const char *message)
        force_sig(SIGKILL, p);
 }
 
-static int oom_kill_task(task_t *p, const char *message)
+static struct mm_struct *oom_kill_task(task_t *p, const char *message)
 {
-       struct mm_struct *mm;
+       struct mm_struct *mm = get_task_mm(p);
        task_t * g, * q;
 
-       mm = p->mm;
-
-       /* WARNING: mm may not be dereferenced since we did not obtain its
-        * value from get_task_mm(p).  This is OK since all we need to do is
-        * compare mm to q->mm below.
-        *
-        * Furthermore, even if mm contains a non-NULL value, p->mm may
-        * change to NULL at any time since we do not hold task_lock(p).
-        * However, this is of no concern to us.
-        */
-
-       if (mm == NULL || mm == &init_mm)
-               return 1;
+       if (!mm)
+               return NULL;
+       if (mm == &init_mm) {
+               mmput(mm);
+               return NULL;
+       }
 
        __oom_kill_task(p, message);
        /*
@@ -285,12 +267,13 @@ static int oom_kill_task(task_t *p, const char *message)
                        __oom_kill_task(q, message);
        while_each_thread(g, q);
 
-       return 0;
+       return mm;
 }
 
-static int oom_kill_process(struct task_struct *p, unsigned long points,
-               const char *message)
+static struct mm_struct *oom_kill_process(struct task_struct *p,
+                               unsigned long points, const char *message)
 {
+       struct mm_struct *mm;
        struct task_struct *c;
        struct list_head *tsk;
 
@@ -301,8 +284,9 @@ static int oom_kill_process(struct task_struct *p, unsigned long points,
                c = list_entry(tsk, struct task_struct, sibling);
                if (c->mm == p->mm)
                        continue;
-               if (!oom_kill_task(c, message))
-                       return 0;
+               mm = oom_kill_task(c, message);
+               if (mm)
+                       return mm;
        }
        return oom_kill_task(p, message);
 }
@@ -317,6 +301,7 @@ static int oom_kill_process(struct task_struct *p, unsigned long points,
  */
 void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
 {
+       struct mm_struct *mm = NULL;
        task_t *p;
        unsigned long points = 0;
 
@@ -336,12 +321,12 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
         */
        switch (constrained_alloc(zonelist, gfp_mask)) {
        case CONSTRAINT_MEMORY_POLICY:
-               oom_kill_process(current, points,
+               mm = oom_kill_process(current, points,
                                "No available memory (MPOL_BIND)");
                break;
 
        case CONSTRAINT_CPUSET:
-               oom_kill_process(current, points,
+               mm = oom_kill_process(current, points,
                                "No available memory in cpuset");
                break;
 
@@ -363,7 +348,8 @@ retry:
                        panic("Out of memory and no killable processes...\n");
                }
 
-               if (oom_kill_process(p, points, "Out of memory"))
+               mm = oom_kill_process(p, points, "Out of memory");
+               if (!mm)
                        goto retry;
 
                break;
@@ -372,6 +358,8 @@ retry:
 out:
        read_unlock(&tasklist_lock);
        cpuset_unlock();
+       if (mm)
+               mmput(mm);
 
        /*
         * Give "p" a good chance of killing itself before we