This is a note to let you know that I've just added the patch titled
blk-iolatency: Fix memory leak on add_disk() failures
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
blk-iolatency-fix-memory-leak-on-add_disk-failures.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 813e693023ba10da9e75067780f8378465bf27cc Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@xxxxxxxxxx>
Date: Sat, 10 Dec 2022 08:33:10 -1000
Subject: blk-iolatency: Fix memory leak on add_disk() failures
From: Tejun Heo <tj@xxxxxxxxxx>
commit 813e693023ba10da9e75067780f8378465bf27cc upstream.
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@xxxxxxxxxx>
Reported-by: darklight2357@xxxxxxxxxx
Cc: Josef Bacik <josef@xxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Fixes: d70675121546 ("block: introduce blk-iolatency io controller")
Cc: stable@xxxxxxxxxxxxxxx # v4.19+
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/Y5TQ5gm3O4HXrXR3@xxxxxxxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-cgroup.c | 2 ++
1 file changed, 2 insertions(+)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -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.
@@ -1275,6 +1276,7 @@ err_unlock:
void blkcg_exit_disk(struct gendisk *disk)
{
blkg_destroy_all(disk);
+ rq_qos_exit(disk->queue);
blk_throtl_exit(disk);
}
Patches currently in stable-queue which might be from tj@xxxxxxxxxx are
queue-6.1/blk-iolatency-fix-memory-leak-on-add_disk-failures.patch
queue-6.1/selftests-cgroup-fix-unsigned-comparison-with-less-t.patch
