Messages in this thread | | | Date | Thu, 15 Mar 2012 09:50:57 -0700 | From | Tejun Heo <> | Subject | Re: [PATCH block/for-3.4/core] cfq: fix cfqg ref handling when BLK_CGROUP && !CFQ_GROUP_IOSCHED |
| |
Hello,
On Thu, Mar 15, 2012 at 12:46:21PM -0400, Vivek Goyal wrote: > On Thu, Mar 15, 2012 at 09:35:46AM -0700, Tejun Heo wrote: > > [..] > > --- > > Yeap, forgot to test that config combination. Fengguang, can you > > please test this patch? Jens, once Fengguang confirms the fix, can > > you please apply this on top of for-3.4/core along with the pending > > stats updates? > > I was working on similar patch and you beat me to it. :-) One comment > below.
:)
> [..] > > @@ -3533,7 +3551,7 @@ static int cfq_init_queue(struct request > > > > spin_lock_irq(q->queue_lock); > > cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group); > > - blkg_put(cfqg_to_blkg(cfqd->root_group)); > > + cfqg_put(cfqd->root_group); > > This seems to be a spurious cfqg_put()? Which reference we are putting > down here?
The extra ref from cfq_link_cfqq_cfqg() for oom_cfqq; otherwise, we need an extra cfq_put() in cfq_exit_queue(). I thought I wrote comment about that somewhere. Hmmm.... apparently not. The thing is that oom_cfqq doesn't go through proper cfqq destruction and thus never puts the extra ref to root cfqg.
Thanks.
-- tejun
| |