blk-mq: fix possible deadlocks #483
Open
+159
−123
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Author
|
Upstream branch: 623fb99 |
blktests-ci
bot
force-pushed
the
linus-master_base
branch
from
f962a4d to
06634b5
Compare
To move implementation details inside blk-wbt.c, prepare to fix possible deadlock to call wbt_init() while queue is frozen in the next patch. Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Hannes Reinecke <hare@suse.de>
…_counter If wbt is disabled by default and user configures wbt by sysfs, queue will be frozen first and then pcpu_alloc_mutex will be held in blk_stat_alloc_callback(). Fix this problem by allocating memory first before queue frozen. Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Ming Lei <ming.lei@redhat.com>
There is already a helper blk_mq_debugfs_register_rqos() to register one rqos, however this helper is called synchronously when the rqos is created with queue frozen. Prepare to fix possible deadlock to create blk-mq debugfs entries while queue is still frozen. Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Hannes Reinecke <hare@suse.de>
Currently rq-qos debugfs entries are created from rq_qos_add(), while rq_qos_add() can be called while queue is still frozen. This can deadlock because creating new entries can trigger fs reclaim. Fix this problem by delaying creating rq-qos debugfs entries after queue is unfrozen. - For wbt, 1) it can be initialized by default, fix it by calling new helper after wbt_init() from wbt_init_enable_default(); 2) it can be initialized by sysfs, fix it by calling new helper after queue is unfrozen from wbt_set_lat(). - For iocost and iolatency, they can only be initialized by blkcg configuration, however, they don't have debugfs entries for now, hence they are not handled yet. Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de>
Because it's only used inside blk-mq-debugfs.c now. Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de>
Because this helper is only used by iocost and iolatency, while they don't have debugfs entries. Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de>
…hctxs() In blk_mq_update_nr_hw_queues(), debugfs_mutex is not held while creating debugfs entries for hctxs. Hence add debugfs_mutex there, it's safe because queue is not frozen. Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de>
Creating new debugfs entries can trigger fs reclaim, hence we can't do this with queue frozen, meanwhile, other locks that can be held while queue is frozen should not be held as well. Signed-off-by: Yu Kuai <yukuai@fnnas.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de>
Author
|
Upstream branch: b543459 |
blktests-ci
bot
force-pushed
the
series/1036552=>linus-master
branch
from
03994c0 to
14665e3
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Pull request for series with
subject: blk-mq: fix possible deadlocks
version: 8
url: https://patchwork.kernel.org/project/linux-block/list/?series=1040275