This is a note to let you know that I've just added the patch titled
block, bfq: protect 'bfqd->queued' by 'bfqd->lock'
to the 4.19-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-bfq-protect-bfqd-queued-by-bfqd-lock.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 181490d5321806e537dc5386db5ea640b826bf78 Mon Sep 17 00:00:00 2001
From: Yu Kuai <yukuai3@xxxxxxxxxx>
Date: Fri, 13 May 2022 10:35:06 +0800
Subject: block, bfq: protect 'bfqd->queued' by 'bfqd->lock'
From: Yu Kuai <yukuai3@xxxxxxxxxx>
commit 181490d5321806e537dc5386db5ea640b826bf78 upstream.
If bfq_schedule_dispatch() is called from bfq_idle_slice_timer_body(),
then 'bfqd->queued' is read without holding 'bfqd->lock'. This is
wrong since it can be wrote concurrently.
Fix the problem by holding 'bfqd->lock' in such case.
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220513023507.2625717-2-yukuai3@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Cc: Khazhy Kumykov <khazhy@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/bfq-iosched.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -416,6 +416,8 @@ static struct bfq_io_cq *bfq_bic_lookup(
*/
void bfq_schedule_dispatch(struct bfq_data *bfqd)
{
+ lockdep_assert_held(&bfqd->lock);
+
if (bfqd->queued != 0) {
bfq_log(bfqd, "schedule dispatch");
blk_mq_run_hw_queues(bfqd->queue, true);
@@ -5278,8 +5280,8 @@ bfq_idle_slice_timer_body(struct bfq_dat
bfq_bfqq_expire(bfqd, bfqq, true, reason);
schedule_dispatch:
- spin_unlock_irqrestore(&bfqd->lock, flags);
bfq_schedule_dispatch(bfqd);
+ spin_unlock_irqrestore(&bfqd->lock, flags);
}
/*
Patches currently in stable-queue which might be from yukuai3@xxxxxxxxxx are
queue-4.19/block-bfq-protect-bfqd-queued-by-bfqd-lock.patch
