This is a note to let you know that I've just added the patch titled
blk-iocost: ioc_pd_free() shouldn't assume irq disabled
to the 5.4-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-iocost-ioc_pd_free-shouldn-t-assume-irq-disabled.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5aeac7c4b16069aae49005f0a8d4526baa83341b Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@xxxxxxxxxx>
Date: Tue, 1 Sep 2020 14:52:31 -0400
Subject: blk-iocost: ioc_pd_free() shouldn't assume irq disabled
From: Tejun Heo <tj@xxxxxxxxxx>
commit 5aeac7c4b16069aae49005f0a8d4526baa83341b upstream.
ioc_pd_free() grabs irq-safe ioc->lock without ensuring that irq is disabled
when it can be called with irq disabled or enabled. This has a small chance
of causing A-A deadlocks and triggers lockdep splats. Use irqsave operations
instead.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Fixes: 7caa47151ab2 ("blkcg: implement blk-iocost")
Cc: stable@xxxxxxxxxxxxxxx # v5.4+
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-iocost.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -2074,14 +2074,15 @@ static void ioc_pd_free(struct blkg_poli
{
struct ioc_gq *iocg = pd_to_iocg(pd);
struct ioc *ioc = iocg->ioc;
+ unsigned long flags;
if (ioc) {
- spin_lock(&ioc->lock);
+ spin_lock_irqsave(&ioc->lock, flags);
if (!list_empty(&iocg->active_list)) {
propagate_active_weight(iocg, 0, 0);
list_del_init(&iocg->active_list);
}
- spin_unlock(&ioc->lock);
+ spin_unlock_irqrestore(&ioc->lock, flags);
hrtimer_cancel(&iocg->waitq_timer);
hrtimer_cancel(&iocg->delay_timer);
Patches currently in stable-queue which might be from tj@xxxxxxxxxx are
queue-5.4/libata-implement-ata_horkage_max_trim_128m-and-apply-to-sandisks.patch
queue-5.4/blk-iocost-ioc_pd_free-shouldn-t-assume-irq-disabled.patch
