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[209.147.138.224]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-759cb15699esm1766876b3a.82.2025.07.18.14.11.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Jul 2025 14:11:56 -0700 (PDT) Date: Fri, 18 Jul 2025 14:11:54 -0700 From: Xiang Mei To: Dan Carpenter Cc: xiyou.wangcong@gmail.com, netdev@vger.kernel.org Subject: Re: [PATCH v1] net/sched: sch_qfq: Avoid triggering might_sleep in atomic context in qfq_delete_class Message-ID: References: <20250717230128.159766-1-xmei5@asu.edu> <01463f6f-a45b-4122-a7cf-8fbf7889fd48@suswa.mountain> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01463f6f-a45b-4122-a7cf-8fbf7889fd48@suswa.mountain> On Fri, Jul 18, 2025 at 10:43:22PM +0300, Dan Carpenter wrote: > On Thu, Jul 17, 2025 at 04:01:28PM -0700, Xiang Mei wrote: > > might_sleep could be trigger in the atomic context in qfq_delete_class. > > > > qfq_destroy_class was moved into atomic context locked > > by sch_tree_lock to avoid a race condition bug on > > qfq_aggregate. However, might_sleep could be triggered by > > qfq_destroy_class, which introduced sleeping in atomic context (path: > > qfq_destroy_class->qdisc_put->__qdisc_destroy->lockdep_unregister_key > > ->might_sleep). > > > > Considering the race is on the qfq_aggregate objects, keeping > > qfq_rm_from_agg in the lock but moving the left part out can solve > > this issue. > > > > Fixes: 5e28d5a3f774 ("net/sched: sch_qfq: Fix race condition on qfq_aggregate") > > Reported-by: Dan Carpenter > > Signed-off-by: Xiang Mei > > Link: https://patch.msgid.link/4a04e0cc-a64b-44e7-9213-2880ed641d77@sabinyo.mountain > > --- > > v1: Avoid might_sleep in atomic context > > No need for this line on the first version of a patch. It's just to > track changes between versions. > > Anyway, looks good. Thanks! > > Reviewed-by: Dan Carpenter > > regards, > dan carpenter > > Thanks so much for the tip and both of your reviews.