From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 139BD42A9F; Tue, 28 Nov 2023 21:10:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZB0kq2Aq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C61AAC433C7; Tue, 28 Nov 2023 21:10:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701205823; bh=tU9f6DT2W4nxeMj/TXZs4n8BgSihvgJc+kQy9yEDCAY=; h=From:To:Cc:Subject:Date:From; b=ZB0kq2Aq2U9v13f/oegVmU4gHNMAuVdUzXMeUFcDK7dKx/T3fjnaFEmYsQILswxf9 s+EPvTiSWTbZogFnbs8ef+RPicZjqQZIVvdZj/sHTF76PloqEjZpMbsFtH8JbrQFm9 BDrcI5C403DHAAuhyy+rcG6ONY+JI2ask3vxwxHyI/H9q/rbljR49+PNCqa52zudrq 58PNRW7V+cZlRiGMkY/CLPmE4NjXv/RQ+VndHaNgyETltllgGxXoYevBkEMXPwYTdK VqemzSS3Erkpb15ex4AZfS+y4ww3pu37muegZ11nYg6le42nIcKZdb0lafHnOVo9+T E0/SqWc011lfw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ming Lei , Changhui Zhong , Jens Axboe , Sasha Levin , tj@kernel.org, josef@toxicpanda.com, cgroups@vger.kernel.org, linux-block@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 1/7] blk-throttle: fix lockdep warning of "cgroup_mutex or RCU read lock required!" Date: Tue, 28 Nov 2023 16:10:11 -0500 Message-ID: <20231128211018.877548-1-sashal@kernel.org> X-Mailer: git-send-email 2.42.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 4.14.331 Content-Transfer-Encoding: 8bit From: Ming Lei [ Upstream commit 27b13e209ddca5979847a1b57890e0372c1edcee ] Inside blkg_for_each_descendant_pre(), both css_for_each_descendant_pre() and blkg_lookup() requires RCU read lock, and either cgroup_assert_mutex_or_rcu_locked() or rcu_read_lock_held() is called. Fix the warning by adding rcu read lock. Reported-by: Changhui Zhong Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20231117023527.3188627-2-ming.lei@redhat.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-throttle.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index fcbbe2e45a2bb..e52a9632993a7 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1391,6 +1391,7 @@ static void tg_conf_updated(struct throtl_grp *tg, bool global) tg_bps_limit(tg, READ), tg_bps_limit(tg, WRITE), tg_iops_limit(tg, READ), tg_iops_limit(tg, WRITE)); + rcu_read_lock(); /* * Update has_rules[] flags for the updated tg's subtree. A tg is * considered to have rules if either the tg itself or any of its @@ -1418,6 +1419,7 @@ static void tg_conf_updated(struct throtl_grp *tg, bool global) this_tg->latency_target = max(this_tg->latency_target, parent_tg->latency_target); } + rcu_read_unlock(); /* * We're already holding queue_lock and know @tg is valid. Let's -- 2.42.0