This is a note to let you know that I've just added the patch titled
block, bfq: put async queues for root bfq groups too
to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: block-bfq-put-async-queues-for-root-bfq-groups-too.patch and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Mon Apr 9 10:16:32 CEST 2018
From: Paolo Valente paolo.valente@linaro.org Date: Tue, 9 Jan 2018 10:27:58 +0100 Subject: block, bfq: put async queues for root bfq groups too
From: Paolo Valente paolo.valente@linaro.org
[ Upstream commit 52257ffbfcaf58d247b13fb148e27ed17c33e526 ]
For each pair [device for which bfq is selected as I/O scheduler, group in blkio/io], bfq maintains a corresponding bfq group. Each such bfq group contains a set of async queues, with each async queue created on demand, i.e., when some I/O request arrives for it. On creation, an async queue gets an extra reference, to make sure that the queue is not freed as long as its bfq group exists. Accordingly, to allow the queue to be freed after the group exited, this extra reference must released on group exit.
The above holds also for a bfq root group, i.e., for the bfq group corresponding to the root blkio/io root for a given device. Yet, by mistake, the references to the existing async queues of a root group are not released when the latter exits. This causes a memory leak when the instance of bfq for a given device exits. In a similar vein, bfqg_stats_xfer_dead is not executed for a root group.
This commit fixes bfq_pd_offline so that the latter executes the above missing operations for a root group too.
Reported-by: Holger Hoffstätte holger@applied-asynchrony.com Reported-by: Guoqing Jiang gqjiang@suse.com Tested-by: Holger Hoffstätte holger@applied-asynchrony.com Signed-off-by: Davide Ferrari davideferrari8@gmail.com Signed-off-by: Paolo Valente paolo.valente@linaro.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/bfq-cgroup.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -775,10 +775,11 @@ static void bfq_pd_offline(struct blkg_p unsigned long flags; int i;
+ spin_lock_irqsave(&bfqd->lock, flags); + if (!entity) /* root group */ - return; + goto put_async_queues;
- spin_lock_irqsave(&bfqd->lock, flags); /* * Empty all service_trees belonging to this group before * deactivating the group itself. @@ -809,6 +810,8 @@ static void bfq_pd_offline(struct blkg_p }
__bfq_deactivate_entity(entity, false); + +put_async_queues: bfq_put_async_queues(bfqd, bfqg);
spin_unlock_irqrestore(&bfqd->lock, flags);
Patches currently in stable-queue which might be from paolo.valente@linaro.org are
queue-4.15/block-bfq-put-async-queues-for-root-bfq-groups-too.patch