cgroups.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Li Nan <linan122@huawei.com>, Yu Kuai <yukuai3@huawei.com>,
	Tejun Heo <tj@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	Sasha Levin <sashal@kernel.org>,
	josef@toxicpanda.com, cgroups@vger.kernel.org,
	linux-block@vger.kernel.org
Subject: [PATCH AUTOSEL 6.6 16/16] blk-iocost: do not WARN if iocg was already offlined
Date: Tue, 23 Apr 2024 07:01:49 -0400	[thread overview]
Message-ID: <20240423110151.1658546-16-sashal@kernel.org> (raw)
In-Reply-To: <20240423110151.1658546-1-sashal@kernel.org>

From: Li Nan <linan122@huawei.com>

[ Upstream commit 01bc4fda9ea0a6b52f12326486f07a4910666cf6 ]

In iocg_pay_debt(), warn is triggered if 'active_list' is empty, which
is intended to confirm iocg is active when it has debt. However, warn
can be triggered during a blkcg or disk removal, if iocg_waitq_timer_fn()
is run at that time:

  WARNING: CPU: 0 PID: 2344971 at block/blk-iocost.c:1402 iocg_pay_debt+0x14c/0x190
  Call trace:
  iocg_pay_debt+0x14c/0x190
  iocg_kick_waitq+0x438/0x4c0
  iocg_waitq_timer_fn+0xd8/0x130
  __run_hrtimer+0x144/0x45c
  __hrtimer_run_queues+0x16c/0x244
  hrtimer_interrupt+0x2cc/0x7b0

The warn in this situation is meaningless. Since this iocg is being
removed, the state of the 'active_list' is irrelevant, and 'waitq_timer'
is canceled after removing 'active_list' in ioc_pd_free(), which ensures
iocg is freed after iocg_waitq_timer_fn() returns.

Therefore, add the check if iocg was already offlined to avoid warn
when removing a blkcg or disk.

Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20240419093257.3004211-1-linan666@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 block/blk-iocost.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 7ee8d85c2c68d..b2e913fe61e67 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -1438,8 +1438,11 @@ static void iocg_pay_debt(struct ioc_gq *iocg, u64 abs_vpay,
 	lockdep_assert_held(&iocg->ioc->lock);
 	lockdep_assert_held(&iocg->waitq.lock);
 
-	/* make sure that nobody messed with @iocg */
-	WARN_ON_ONCE(list_empty(&iocg->active_list));
+	/*
+	 * make sure that nobody messed with @iocg. Check iocg->pd.online
+	 * to avoid warn when removing blkcg or disk.
+	 */
+	WARN_ON_ONCE(list_empty(&iocg->active_list) && iocg->pd.online);
 	WARN_ON_ONCE(iocg->inuse > 1);
 
 	iocg->abs_vdebt -= min(abs_vpay, iocg->abs_vdebt);
-- 
2.43.0


           reply	other threads:[~2024-04-23 11:40 UTC|newest]

Thread overview: expand[flat|nested]  mbox.gz  Atom feed
 [parent not found: <20240423110151.1658546-1-sashal@kernel.org>]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20240423110151.1658546-16-sashal@kernel.org \
    --to=sashal@kernel.org \
    --cc=axboe@kernel.dk \
    --cc=cgroups@vger.kernel.org \
    --cc=josef@toxicpanda.com \
    --cc=linan122@huawei.com \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=tj@kernel.org \
    --cc=yukuai3@huawei.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).