do_posix_clock_monotonic_gettime(&uptime);
do_each_thread(g, p) {
unsigned long points;
- int releasing;
- /* skip kernel threads */
+ /*
+ * skip kernel threads and tasks which have already released
+ * their mm.
+ */
if (!p->mm)
continue;
- /* skip the init task with pid == 1 */
- if (p->pid == 1)
+ /* skip the init task */
+ if (is_init(p))
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))
+ return ERR_PTR(-1UL);
+
/*
* This is in the process of releasing memory so wait for it
* to finish before killing some other task by mistake.
* go ahead if it is exiting: this will simply set TIF_MEMDIE,
* which will allow it to gain access to memory reserves in
* the process of exiting and releasing its resources.
- * Otherwise we could get an OOM deadlock.
+ * Otherwise we could get an easy OOM deadlock.
*/
- releasing = test_tsk_thread_flag(p, TIF_MEMDIE) ||
- p->flags & PF_EXITING;
- if (releasing) {
- /* TASK_DEAD tasks have already released their mm */
- if (p->state == TASK_DEAD)
- continue;
- if (p->flags & PF_EXITING && p == current) {
- chosen = p;
- *ppoints = ULONG_MAX;
- break;
- }
- return ERR_PTR(-1UL);
+ if (p->flags & PF_EXITING) {
+ if (p != current)
+ return ERR_PTR(-1UL);
+
+ chosen = p;
+ *ppoints = ULONG_MAX;
}
+
if (p->oomkilladj == OOM_DISABLE)
continue;
*ppoints = points;
}
} while_each_thread(g, p);
+
return chosen;
}
return;
}
- task_lock(p);
- if (!p->mm || p->mm == &init_mm) {
+ if (!p->mm) {
WARN_ON(1);
printk(KERN_WARNING "tried to kill an mm-less task!\n");
- task_unlock(p);
return;
}
- task_unlock(p);
if (message) {
printk(KERN_ERR "%s: Killed process %d (%s).\n",
* However, this is of no concern to us.
*/
- if (mm == NULL || mm == &init_mm)
+ if (mm == NULL)
return 1;
__oom_kill_task(p, message);