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-rw-r--r--mm/oom_kill.c53
1 files changed, 30 insertions, 23 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index bada3d0..20f41b0 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -204,16 +204,30 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
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.
*
@@ -221,21 +235,16 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
* 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) {
- /* PF_DEAD tasks have already released their mm */
- if (p->flags & PF_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;
@@ -245,6 +254,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
*ppoints = points;
}
} while_each_thread(g, p);
+
return chosen;
}
@@ -255,20 +265,17 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
*/
static void __oom_kill_task(struct task_struct *p, const char *message)
{
- if (p->pid == 1) {
+ if (is_init(p)) {
WARN_ON(1);
printk(KERN_WARNING "tried to kill init!\n");
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",
@@ -302,7 +309,7 @@ static int oom_kill_task(struct task_struct *p, const char *message)
* However, this is of no concern to us.
*/
- if (mm == NULL || mm == &init_mm)
+ if (mm == NULL)
return 1;
__oom_kill_task(p, message);
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