On Wed, Nov 23, 2022 at 02:03:53PM +0800, Kemeng Shi wrote: > Ignore cgroup without io queued in blk_throtl_cancel_bios for two > reasons: > 1. Save cpu cycle for trying to dispatch cgroup which is no io queued. > 2. Avoid non-consistent state that cgroup is inserted to service queue > without THROTL_TG_PENDING set as tg_update_disptime will unconditional > re-insert cgroup to service queue. If we are on the default hierarchy, > IO dispatched from child in tg_dispatch_one_bio will trigger inserting > cgroup to service queue without erase first and ruin the tree. > > Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxx> > --- > block/blk-throttle.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/block/blk-throttle.c b/block/blk-throttle.c > index b33bcf53b36e..acfac916ed99 100644 > --- a/block/blk-throttle.c > +++ b/block/blk-throttle.c > @@ -1728,7 +1728,12 @@ void blk_throtl_cancel_bios(struct gendisk *disk) > * Set the flag to make sure throtl_pending_timer_fn() won't > * stop until all throttled bios are dispatched. > */ > - blkg_to_tg(blkg)->flags |= THROTL_TG_CANCELING; > + tg->flags |= THROTL_TG_CANCELING; > + > + /* No need to dispatch cgroup without io queued */ It's probably more important to mention that putting this in without PENDING set can corrupt the tree in the future through double insertion. > + if (!(tg->flags & THROTL_TG_PENDING)) > + continue; > + Other than than the above comment, Acked-by: Tejun Heo <tj@xxxxxxxxxx> Thanks. -- tejun
