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android/lowmemorykiller: Ignore tasks with freed mm

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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>
This commit is contained in:
Liam Mark 2013-02-07 14:31:36 -08:00 committed by Stephen Boyd
parent 6873da97a3
commit 05d5ad4d0a
5 changed files with 19 additions and 5 deletions
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1
arch/arm/include/asm/thread_info.h
View file

@ -157,6 +157,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
#define TIF_RESTORE_SIGMASK 20
#define TIF_SWITCH_MM 22 /* deferred switch_mm */
#define TIF_MM_RELEASED 23 /* task MM has been released */
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)

10
drivers/staging/android/lowmemorykiller.c
View file

@ -211,6 +211,10 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
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();
@ -264,12 +268,14 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
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;
}

2
include/linux/sched.h
View file

@ -2107,7 +2107,7 @@ static inline void mmdrop(struct mm_struct * mm)
}
/* 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);
/*

6
kernel/exit.c
View file

@ -454,6 +454,7 @@ static void exit_mm(struct task_struct * tsk)
{
struct mm_struct *mm = tsk->mm;
struct core_state *core_state;
int mm_released;
mm_release(tsk, mm);
if (!mm)
@ -499,7 +500,10 @@ static void exit_mm(struct task_struct * tsk)
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);
}
/*

5
kernel/fork.c
View file

@ -623,8 +623,9 @@ EXPORT_SYMBOL_GPL(__mmdrop);
/*
* 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)) {
@ -642,7 +643,9 @@ void mmput(struct mm_struct *mm)
if (mm->binfmt)
module_put(mm->binfmt->module);
mmdrop(mm);
mm_freed = 1;
}
return mm_freed;
}
EXPORT_SYMBOL_GPL(mmput);