This is a note to let you know that I've just added the patch titled
block: make sure local irq is disabled when calling __blkcg_rstat_flush
to the 6.3-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:
block-make-sure-local-irq-is-disabled-when-calling-__blkcg_rstat_flush.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9c39b7a905d84b7da5f59d80f2e455853fea7217 Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@xxxxxxxxxx>
Date: Thu, 22 Jun 2023 16:42:49 +0800
Subject: block: make sure local irq is disabled when calling __blkcg_rstat_flush
From: Ming Lei <ming.lei@xxxxxxxxxx>
commit 9c39b7a905d84b7da5f59d80f2e455853fea7217 upstream.
When __blkcg_rstat_flush() is called from cgroup_rstat_flush*() code
path, interrupt is always disabled.
When we start to flush blkcg per-cpu stats list in __blkg_release()
for avoiding to leak blkcg_gq's reference in commit 20cb1c2fb756
("blk-cgroup: Flush stats before releasing blkcg_gq"), local irq
isn't disabled yet, then lockdep warning may be triggered because
the dependent cgroup locks may be acquired from irq(soft irq) handler.
Fix the issue by disabling local irq always.
Fixes: 20cb1c2fb756 ("blk-cgroup: Flush stats before releasing blkcg_gq")
Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@xxxxxxx>
Closes: https://lore.kernel.org/linux-block/pz2wzwnmn5tk3pwpskmjhli6g3qly7eoknilb26of376c7kwxy@qydzpvt6zpis/T/#u
Cc: stable@xxxxxxxxxxxxxxx
Cc: Jay Shin <jaeshin@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Reviewed-by: Waiman Long <longman@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230622084249.1208005-1-ming.lei@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-cgroup.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -907,6 +907,7 @@ static void __blkcg_rstat_flush(struct b
struct llist_head *lhead = per_cpu_ptr(blkcg->lhead, cpu);
struct llist_node *lnode;
struct blkg_iostat_set *bisc, *next_bisc;
+ unsigned long flags;
rcu_read_lock();
@@ -920,7 +921,7 @@ static void __blkcg_rstat_flush(struct b
* When flushing from cgroup, cgroup_rstat_lock is always held, so
* this lock won't cause contention most of time.
*/
- raw_spin_lock(&blkg_stat_lock);
+ raw_spin_lock_irqsave(&blkg_stat_lock, flags);
/*
* Iterate only the iostat_cpu's queued in the lockless list.
@@ -946,7 +947,7 @@ static void __blkcg_rstat_flush(struct b
blkcg_iostat_update(parent, &blkg->iostat.cur,
&blkg->iostat.last);
}
- raw_spin_unlock(&blkg_stat_lock);
+ raw_spin_unlock_irqrestore(&blkg_stat_lock, flags);
out:
rcu_read_unlock();
}
Patches currently in stable-queue which might be from ming.lei@xxxxxxxxxx are
queue-6.3/block-make-sure-local-irq-is-disabled-when-calling-__blkcg_rstat_flush.patch
