From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 01/27] blk-iocost: ioc_pd_free() shouldn't assume irq disabled Date: Tue, 1 Sep 2020 14:52:31 -0400 Message-ID: <20200901185257.645114-2-tj@kernel.org> References: <20200901185257.645114-1-tj@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=V69TM0TXJZV6Ph3DQcWjjVMFJyyhsm9AOvCWZiY6Tfg=; b=npTqPcLDLPp9IG+8hih3s0n1i8HE84G+rEqAq7/0mzOvX4YAHvQawMoRbgGBQt3Yig 2eneUEERH+HTyLTzXLB4YL2RGRONA0RTWYNtrj47yF3wKaXG1SvQcwpDJCy21eZ5Jsca sZEjiM8Q8sRrkCSCdh7obp3ZwzFnJGVNkTOhuz/R6vNzBKji4+ZPo5x3PfxZMyNd2OBO M4MTsGJ65P64qH13pbf0vQEUgLCZYCKSqoDEAtJXuzOVPMrbIWAIgJY6kryL066yazx7 Vx3KNiFq7vpMib+dcpa+l8yunUwdH0plUmX8yPgAs/DeFZ1XTCDGXi3fKIOkg1FtiVS1 14Ng== In-Reply-To: <20200901185257.645114-1-tj@kernel.org> Sender: stable-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: axboe@kernel.dk Cc: linux-block@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, newella@fb.com, Tejun Heo , stable@vger.kernel.org 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 Fixes: 7caa47151ab2 ("blkcg: implement blk-iocost") Cc: stable@vger.kernel.org # v5.4+ --- block/blk-iocost.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 413e0b5c8e6b..d37b55db2409 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -2092,14 +2092,15 @@ static void ioc_pd_free(struct blkg_policy_data *pd) { 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); -- 2.26.2