From: Anton Vorontsov Date: Mon, 6 Feb 2012 16:29:47 +0000 (+0400) Subject: staging: android/lowmemorykiller: Better mm handling X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=95670001188911f9d466875cd68e3681f39df38a;p=linux-beck.git staging: android/lowmemorykiller: Better mm handling LMK should not directly check for task->mm. The reason is that the process' threads may exit or detach its mm via use_mm(), but other threads may still have a valid mm. To catch this we use find_lock_task_mm(), which walks up all threads and returns an appropriate task (with lock held). Suggested-by: Oleg Nesterov Reviewed-by: Oleg Nesterov Signed-off-by: Anton Vorontsov Acked-by: KOSAKI Motohiro Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c index 63da8447218f..0755e2f0eb18 100644 --- a/drivers/staging/android/lowmemorykiller.c +++ b/drivers/staging/android/lowmemorykiller.c @@ -82,7 +82,7 @@ task_notify_func(struct notifier_block *self, unsigned long val, void *data) static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) { - struct task_struct *p; + struct task_struct *tsk; struct task_struct *selected = NULL; int rem = 0; int tasksize; @@ -134,15 +134,17 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) selected_oom_adj = min_adj; rcu_read_lock(); - for_each_process(p) { - struct mm_struct *mm; + for_each_process(tsk) { + struct task_struct *p; struct signal_struct *sig; int oom_adj; - task_lock(p); - mm = p->mm; + p = find_lock_task_mm(tsk); + if (!p) + continue; + sig = p->signal; - if (!mm || !sig) { + if (!sig) { task_unlock(p); continue; } @@ -151,7 +153,7 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) task_unlock(p); continue; } - tasksize = get_mm_rss(mm); + tasksize = get_mm_rss(p->mm); task_unlock(p); if (tasksize <= 0) continue;