diff options
| author | Vinayak Menon <vinmenon@codeaurora.org> | 2015-05-21 17:12:37 +0530 |
|---|---|---|
| committer | Kyle Yan <kyan@codeaurora.org> | 2016-06-29 15:11:56 -0700 |
| commit | 9ff04770060db13d7d6dcfad1d0d72b4f04eaf26 (patch) | |
| tree | 1c1ac539a0ee7f37bc4570059723e92fa59238f2 /mm/process_reclaim.c | |
| parent | 1ad1a93af4bcd68bd3beb526ec2d64495bc9ce64 (diff) | |
mm: process_reclaim: do not iterate over stale task structs
swap_fn iterates through the threads of selected tasks after
a rcu_read_unlock which is wrong. But we can't extend the
rcu_read_lock since it will result in severe performance
issues. So better avoid iterating over the threads. Just
lock the group leader and use it further.
Change-Id: I36269b1b6619315f33f6f3b49ec73571a66796f2
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Diffstat (limited to 'mm/process_reclaim.c')
| -rw-r--r-- | mm/process_reclaim.c | 31 |
1 files changed, 12 insertions, 19 deletions
diff --git a/mm/process_reclaim.c b/mm/process_reclaim.c index f483f7276597..271fb38e0cb0 100644 --- a/mm/process_reclaim.c +++ b/mm/process_reclaim.c @@ -88,14 +88,17 @@ static int test_task_flag(struct task_struct *p, int flag) { struct task_struct *t = p; - do { + rcu_read_lock(); + for_each_thread(p, t) { task_lock(t); if (test_tsk_thread_flag(t, flag)) { task_unlock(t); + rcu_read_unlock(); return 1; } task_unlock(t); - } while_each_thread(p, t); + } + rcu_read_unlock(); return 0; } @@ -125,10 +128,6 @@ static void swap_fn(struct work_struct *work) 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 (test_task_flag(tsk, TIF_MEMDIE)) continue; @@ -165,20 +164,20 @@ static void swap_fn(struct work_struct *work) } } - for (i = 0; i < si; i++) { - get_task_struct(selected[i].p); + for (i = 0; i < si; i++) total_sz += selected[i].tasksize; - } - - rcu_read_unlock(); /* Skip reclaim if total size is too less */ if (total_sz < SWAP_CLUSTER_MAX) { - for (i = 0; i < si; i++) - put_task_struct(selected[i].p); + rcu_read_unlock(); return; } + for (i = 0; i < si; i++) + get_task_struct(selected[i].p); + + rcu_read_unlock(); + while (si--) { nr_to_reclaim = (selected[si].tasksize * per_swap_size) / total_sz; @@ -186,12 +185,6 @@ static void swap_fn(struct work_struct *work) if (!nr_to_reclaim) nr_to_reclaim = 1; - if ((test_task_flag(selected[si].p, TIF_MM_RELEASED)) - || (test_task_flag(selected[si].p, TIF_MEMDIE))) { - put_task_struct(selected[si].p); - continue; - } - rp = reclaim_task_anon(selected[si].p, nr_to_reclaim); trace_process_reclaim(selected[si].tasksize, |