From: Peter Zijlstra <peterz@infradead.org>
To: Chengming Zhou <zhouchengming@bytedance.com>
Cc: tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
songmuchun@bytedance.com,
Linux Kernel Functional Testing <lkft@linaro.org>,
syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com,
Zhouyi Zhou <zhouzhouyi@gmail.com>
Subject: Re: [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning
Date: Sat, 12 Mar 2022 14:34:45 +0100 [thread overview]
Message-ID: <20220312133445.GA28086@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20220312121913.GA28057@worktop.programming.kicks-ass.net>
On Sat, Mar 12, 2022 at 01:19:13PM +0100, Peter Zijlstra wrote:
> On Sat, Mar 05, 2022 at 11:41:03AM +0800, Chengming Zhou wrote:
> > task_css_set_check() will use rcu_dereference_check() to check for
> > rcu_read_lock_held() on the read-side, which is not true after commit
> > dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This
> > commit drop explicit rcu_read_lock(), change to RCU-sched read-side
> > critical section. So fix the RCU warning by adding check for
> > rcu_read_lock_sched_held().
> >
> > Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock")
> > Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> > Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com
> > Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
> > Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
>
> Thanks, I'll go stick this in sched/core so it's in the same branch that
> caused the problem.
FWIW I never saw this patch because it doesn't instantly look like a
patch I should be interested in. It's classified as 'for-next' and I
don't run -next, sfr does that. Then it's tagged as cgroup, which I also
don't do.
Nowhere does that look like a patch that wants to go in sched/core and
fixes a cpuacct issue.
On top of that, I still don't agree with this, I really think
rcu_dereference_check() itself should be changed.
next prev parent reply other threads:[~2022-03-12 13:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-05 3:41 [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning Chengming Zhou
[not found] ` <CGME20220309071027eucas1p1f066b42f49e524404d898929b60b344f@eucas1p1.samsung.com>
2022-03-09 7:10 ` Marek Szyprowski
2022-03-09 18:10 ` Tejun Heo
2022-03-12 12:19 ` Peter Zijlstra
2022-03-12 13:34 ` Peter Zijlstra [this message]
2022-03-12 15:54 ` [External] " Chengming Zhou
2022-03-12 12:37 ` [tip: sched/core] cgroup: Fix " tip-bot2 for Chengming Zhou
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