Hi Josef, On Fri, Aug 31, 2018 at 11:30:08AM -0400, Josef Bacik wrote: > On Thu, Aug 30, 2018 at 09:53:44PM -0400, Dennis Zhou wrote: > > diff --git a/block/blk-throttle.c b/block/blk-throttle.c > > index a3eede00d302..c626e1f7cdcd 100644 > > --- a/block/blk-throttle.c > > +++ b/block/blk-throttle.c > > @@ -2129,8 +2129,9 @@ static inline void throtl_update_latency_buckets(struct throtl_data *td) > > static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio) > > { > > #ifdef CONFIG_BLK_DEV_THROTTLING_LOW > > - if (bio->bi_css) > > - bio_associate_blkg(bio, tg_to_blkg(tg)); > > + /* fallback to root_blkg if we fail to get a blkg ref */ > > + if (bio->bi_css && bio_associate_blkg(bio, tg_to_blkg(tg))) > > + bio_associate_blkg(bio, bio->bi_disk->queue->root_blkg); > > Except if we've already assocated a blkg this is just extra, can we do > > if (bio->bi_css && (bio_associate_blkg(bio, tg_to_blkg(tg)) == -ENODEV)) > > to make it clear that we're only attaching it to the root if we failed to attach > a blkg at all? Thanks, Done in v2. Thanks, Dennis