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McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Josh Triplett , Boqun Feng , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "rcu@vger.kernel.org" Subject: Re: [PATCH] rcu: Enable runtime reset of the RCU stall panic count Date: Wed, 7 Oct 2026 10:56:39 +0800 Message-ID: X-Mailer: git-send-email 2.43.0 In-Reply-To: <53383f19-3d54-405b-85af-f597b69befe6@nvidia.com> References: <20261004-rcu-v1-1-3799a44367f1@gmail.com> <00F6D386-FE41-42E3-9B89-07381A49E061@nvidia.com> <53383f19-3d54-405b-85af-f597b69befe6@nvidia.com> Mail-Followup-To: Cunlong Li , Joel Fernandes , Jonathan Corbet , Shuah Khan , Randy Dunlap , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Josh Triplett , Boqun Feng , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "rcu@vger.kernel.org" Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8bit On Tue, Oct 06, 2026 at 05:27:51PM -0400, Joel Fernandes wrote: > > > On 10/6/2026 9:17 AM, Cunlong Li wrote: > >> It sounds like you do know that it is likely transient - but based on this description and the below, it sounds like you have not yet found a use of this patch. > >> > >> > > To be precise, we worry that some of the stalls were transient, so a > > panic reboot would affect the users. But we have no hard evidence > > either way: every incident ended in a forced reset, and the dmesg was > > lost. Going forward, we plan to enable the NMI and kdump to keep > > investigating the cause of the RCU stalls. We will also monitor dmesg > > to confirm whether transient RCU stalls actually occur. > > > Right, I just worry that if you're not seeing recoverable/transient stalls and > you start using this patch, then you might be causing side-effects that don't > really help your problem and might be masking the real issue. It would be good > to debug this further, and fix the right way IMO. > > If you show that this patch indeed helps your problem, we can consider it for > 7.5, but there's little bit of time. :-) Hi Joel, Understood, thanks. We will keep monitoring dmesg for the root cause. Once we observe self-recovering RCU stalls, we will resubmit the patch with the evidence. Thanks, Cunlong > > Thanks, > > Joel Fernandes > >