This is a note to let you know that I've just added the patch titled
Revert "blk-cgroup: synchronize pd_free_fn() from blkg_free_workfn() and blkcg_deactivate_policy()"
to the 6.2-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:
revert-blk-cgroup-synchronize-pd_free_fn-from-blkg_free_workfn-and-blkcg_deactivate_policy.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From cdd86c17d2e3bb1b2f119ee722c632e2f7ef3d30 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Date: Sat, 11 Mar 2023 10:34:32 +0100
Subject: Revert "blk-cgroup: synchronize pd_free_fn() from blkg_free_workfn() and blkcg_deactivate_policy()"
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
This reverts commit bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a which is
commit f1c006f1c6850c14040f8337753a63119bba39b9 upstream.
It is reported to cause problems, as only 2 of the 3 patch series were
applied to the stable branches.
Reported-by: Mike Cloaked <mike.cloaked@xxxxxxxxx>
Reported-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Yu Kuai <yukuai3@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Sasha Levin <sashal@xxxxxxxxxx>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217174
Link: https://lore.kernel.org/r/ZAuPkCn49urWBN5P@sol.localdomain
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-cgroup.c | 35 ++++++-----------------------------
include/linux/blkdev.h | 1 -
2 files changed, 6 insertions(+), 30 deletions(-)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -118,32 +118,16 @@ static void blkg_free_workfn(struct work
{
struct blkcg_gq *blkg = container_of(work, struct blkcg_gq,
free_work);
- struct request_queue *q = blkg->q;
int i;
- /*
- * pd_free_fn() can also be called from blkcg_deactivate_policy(),
- * in order to make sure pd_free_fn() is called in order, the deletion
- * of the list blkg->q_node is delayed to here from blkg_destroy(), and
- * blkcg_mutex is used to synchronize blkg_free_workfn() and
- * blkcg_deactivate_policy().
- */
- if (q)
- mutex_lock(&q->blkcg_mutex);
-
for (i = 0; i < BLKCG_MAX_POLS; i++)
if (blkg->pd[i])
blkcg_policy[i]->pd_free_fn(blkg->pd[i]);
if (blkg->parent)
blkg_put(blkg->parent);
-
- if (q) {
- list_del_init(&blkg->q_node);
- mutex_unlock(&q->blkcg_mutex);
- blk_put_queue(q);
- }
-
+ if (blkg->q)
+ blk_put_queue(blkg->q);
free_percpu(blkg->iostat_cpu);
percpu_ref_exit(&blkg->refcnt);
kfree(blkg);
@@ -474,14 +458,9 @@ static void blkg_destroy(struct blkcg_gq
lockdep_assert_held(&blkg->q->queue_lock);
lockdep_assert_held(&blkcg->lock);
- /*
- * blkg stays on the queue list until blkg_free_workfn(), see details in
- * blkg_free_workfn(), hence this function can be called from
- * blkcg_destroy_blkgs() first and again from blkg_destroy_all() before
- * blkg_free_workfn().
- */
- if (hlist_unhashed(&blkg->blkcg_node))
- return;
+ /* Something wrong if we are trying to remove same group twice */
+ WARN_ON_ONCE(list_empty(&blkg->q_node));
+ WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
for (i = 0; i < BLKCG_MAX_POLS; i++) {
struct blkcg_policy *pol = blkcg_policy[i];
@@ -493,6 +472,7 @@ static void blkg_destroy(struct blkcg_gq
blkg->online = false;
radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
+ list_del_init(&blkg->q_node);
hlist_del_init_rcu(&blkg->blkcg_node);
/*
@@ -1293,7 +1273,6 @@ int blkcg_init_disk(struct gendisk *disk
int ret;
INIT_LIST_HEAD(&q->blkg_list);
- mutex_init(&q->blkcg_mutex);
new_blkg = blkg_alloc(&blkcg_root, disk, GFP_KERNEL);
if (!new_blkg)
@@ -1531,7 +1510,6 @@ void blkcg_deactivate_policy(struct requ
if (queue_is_mq(q))
blk_mq_freeze_queue(q);
- mutex_lock(&q->blkcg_mutex);
spin_lock_irq(&q->queue_lock);
__clear_bit(pol->plid, q->blkcg_pols);
@@ -1550,7 +1528,6 @@ void blkcg_deactivate_policy(struct requ
}
spin_unlock_irq(&q->queue_lock);
- mutex_unlock(&q->blkcg_mutex);
if (queue_is_mq(q))
blk_mq_unfreeze_queue(q);
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -484,7 +484,6 @@ struct request_queue {
DECLARE_BITMAP (blkcg_pols, BLKCG_MAX_POLS);
struct blkcg_gq *root_blkg;
struct list_head blkg_list;
- struct mutex blkcg_mutex;
#endif
struct queue_limits limits;
Patches currently in stable-queue which might be from gregkh@xxxxxxxxxxxxxxxxxxx are
queue-6.2/revert-blk-cgroup-synchronize-pd_free_fn-from-blkg_free_workfn-and-blkcg_deactivate_policy.patch
queue-6.2/revert-blk-cgroup-dropping-parent-refcount-after-pd_free_fn-is-done.patch
