Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210511113257.2094-1-rocco.yue@mediatek.com>
In-Reply-To: <20210511113257.2094-1-rocco.yue@mediatek.com>
From:   Cong Wang <xiyou.wangcong@gmail.com>
Date:   Tue, 11 May 2021 10:00:43 -0700
Message-ID: <CAM_iQpVWSJ8BdRoLDX0MdiqmJn2dp+U9JM4mcfzRbVn4MZbzcg@mail.gmail.com>
Subject: Re: [PATCH][v3] rtnetlink: add rtnl_lock debug log
To:     Rocco yue <rocco.yue@mediatek.com>
Cc:     "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, May 11, 2021 at 4:46 AM Rocco yue <rocco.yue@mediatek.com> wrote:
>
> From: Rocco Yue <rocco.yue@mediatek.com>
>
> We often encounter system hangs caused by certain process
> holding rtnl_lock for a long time. Even if there is a lock
> detection mechanism in Linux, it is a bit troublesome and
> affects the system performance. We hope to add a lightweight
> debugging mechanism for detecting rtnl_lock.

Any reason why this is specific to RTNL lock? To me holding
a mutex lock for a long time is problematic for any mutex.
I have seen some fs mutex being held for a long time caused
many hung tasks in the system.

Thanks.