system/linux
system/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux synced 2024-11-05 18:23:50 +00:00
Code Issues Projects Releases Packages Wiki Activity

blk-iolatency: Fix memory leak on add_disk() failures

Browse source 
When a gendisk is successfully initialized but add_disk() fails such as when
a loop device has invalid number of minor device numbers specified,
blkcg_init_disk() is called during init and then blkcg_exit_disk() during
error handling. Unfortunately, iolatency gets initialized in the former but
doesn't get cleaned up in the latter.

This is because, in non-error cases, the cleanup is performed by
del_gendisk() calling rq_qos_exit(), the assumption being that rq_qos
policies, iolatency being one of them, can only be activated once the disk
is fully registered and visible. That assumption is true for wbt and iocost,
but not so for iolatency as it gets initialized before add_disk() is called.

It is desirable to lazy-init rq_qos policies because they are optional
features and add to hot path overhead once initialized - each IO has to walk
all the registered rq_qos policies. So, we want to switch iolatency to lazy
init too. However, that's a bigger change. As a fix for the immediate
problem, let's just add an extra call to rq_qos_exit() in blkcg_exit_disk().
This is safe because duplicate calls to rq_qos_exit() become noop's.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: darklight2357@icloud.com
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: d706751215 ("block: introduce blk-iolatency io controller")
Cc: stable@vger.kernel.org # v4.19+
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/Y5TQ5gm3O4HXrXR3@slm.duckdns.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2022-12-10 08:33:10 -10:00 committed by Jens Axboe
parent 85c5019771
commit 813e693023
1 changed files with 2 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
block/blk-cgroup.c
View file

@ -33,6 +33,7 @@
#include "blk-cgroup.h"
#include "blk-ioprio.h"
#include "blk-throttle.h"
#include "blk-rq-qos.h"
/*
* blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation.
@ -1322,6 +1323,7 @@ int blkcg_init_disk(struct gendisk *disk)
void blkcg_exit_disk(struct gendisk *disk)
{
blkg_destroy_all(disk);
rq_qos_exit(disk->queue);
blk_throtl_exit(disk);
}