android/lowmemorykiller: Ignore tasks with freed mm
A killed task can stay in the task list long after its
memory has been returned to the system, therefore
ignore any tasks whose mm struct has been freed.
Change-Id: I76394b203b4ab2312437c839976f0ecb7b6dde4e
CRs-fixed: 450383
Signed-off-by: Liam Mark <lmark@codeaurora.org>
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 0f04d84..67d6443 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -153,7 +153,7 @@
#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 20
#define TIF_SECCOMP 21
-
+#define TIF_MM_RELEASED 22 /* task MM has been released */
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index 34ec396..71554ed 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -207,6 +207,10 @@
if (tsk->flags & PF_KTHREAD)
continue;
+ /* if task no longer has any memory ignore it */
+ if (test_task_flag(tsk, TIF_MM_RELEASED))
+ continue;
+
if (time_before_eq(jiffies, lowmem_deathpending_timeout)) {
if (test_task_flag(tsk, TIF_MEMDIE)) {
rcu_read_unlock();
@@ -251,12 +255,14 @@
send_sig(SIGKILL, selected, 0);
set_tsk_thread_flag(selected, TIF_MEMDIE);
rem -= selected_tasksize;
+ rcu_read_unlock();
/* give the system time to free up the memory */
msleep_interruptible(20);
- }
+ } else
+ rcu_read_unlock();
+
lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
nr_to_scan, sc->gfp_mask, rem);
- rcu_read_unlock();
mutex_unlock(&scan_mutex);
return rem;
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0a1428e..67889bf 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2304,7 +2304,7 @@
}
/* mmput gets rid of the mappings and all user-space */
-extern void mmput(struct mm_struct *);
+extern int mmput(struct mm_struct *);
/* Grab a reference to a task's mm, if it is not already going away */
extern struct mm_struct *get_task_mm(struct task_struct *task);
/*
diff --git a/kernel/exit.c b/kernel/exit.c
index d8bd3b42..6096e80 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -639,6 +639,7 @@
{
struct mm_struct *mm = tsk->mm;
struct core_state *core_state;
+ int mm_released;
mm_release(tsk, mm);
if (!mm)
@@ -683,7 +684,10 @@
enter_lazy_tlb(mm, current);
task_unlock(tsk);
mm_update_next_owner(mm);
- mmput(mm);
+
+ mm_released = mmput(mm);
+ if (mm_released)
+ set_tsk_thread_flag(tsk, TIF_MM_RELEASED);
}
/*
diff --git a/kernel/fork.c b/kernel/fork.c
index c0bf8c7..0de735c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -581,8 +581,9 @@
/*
* Decrement the use count and release all resources for an mm.
*/
-void mmput(struct mm_struct *mm)
+int mmput(struct mm_struct *mm)
{
+ int mm_freed = 0;
might_sleep();
if (atomic_dec_and_test(&mm->mm_users)) {
@@ -600,7 +601,9 @@
if (mm->binfmt)
module_put(mm->binfmt->module);
mmdrop(mm);
+ mm_freed = 1;
}
+ return mm_freed;
}
EXPORT_SYMBOL_GPL(mmput);