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Tue, 19 May 2026 06:19:02 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Tue, 19 May 2026 15:19:00 +0200 To: Boqun Feng Cc: Uladzislau Rezki , Thorsten Leemhuis , paulmck@kernel.org, Boqun Feng , Joel Fernandes , RCU , LKML , Vasily Gorbik , Frederic Weisbecker , Samir , Shrikanth Hegde , Tejun Heo , Linux kernel regressions list , Jiri Slaby Subject: Re: [PATCH -next v1 05/12] srcu: Don't queue workqueue handlers to never-online CPUs Message-ID: References: <20260511175448.153326-1-urezki@gmail.com> <20260511175448.153326-6-urezki@gmail.com> <3dd5cce0-51f9-4cf1-81b8-246e6c6a633a@paulmck-laptop> <53d546e4-8db0-4e14-a79d-270212081be7@leemhuis.info> Precedence: bulk X-Mailing-List: rcu@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: On Mon, May 18, 2026 at 12:30:08PM -0700, Boqun Feng wrote: > On Mon, May 18, 2026 at 07:05:36PM +0200, Uladzislau Rezki wrote: > > On Mon, May 18, 2026 at 09:13:46AM -0700, Boqun Feng wrote: > > > On Sun, May 17, 2026 at 09:11:10PM +0200, Thorsten Leemhuis wrote: > > > > On 5/17/26 20:03, Paul E. McKenney wrote: > > > > > On Sun, May 17, 2026 at 02:47:55PM +0200, Uladzislau Rezki wrote: > > > > >> On Wed, May 13, 2026 at 12:38:01PM +0200, Thorsten Leemhuis wrote: > > > > >>> On 5/11/26 19:54, Uladzislau Rezki (Sony) wrote: > > > > >>>> From: "Paul E. McKenney" > > > > >>>> > > > > >>>> While an srcu_struct structure is in the midst of switching from CPU-0 > > > > >>>> to all-CPUs state, it can attempt to invoke callbacks for CPUs that > > > > >>>> have never been online. Worse yet, it can attempt in invoke callbacks > > > > >>>> for CPUs that never will be online, even including imaginary CPUs not in > > > > >>>> cpu_possible_mask. This can cause hangs on s390, > > > > >>> > > > > >>> Uladzislau, Paul, according to the fixes tag below this change fixes a > > > > >>> change that went into 7.0-rc6 -- and apparently causes a "hang" on some > > > > >>> architectures. So shouldn't this be heading to mainline instead of > > > > >>> -next? Ideally with a stable tag to ensure backporting to 7.0.y, but > > > > >>> that is a separate decision? > > > > >>> > > > > > > FWIW, I'm happy to create an urgent PR to Linus with this fix. Since it > > > fixes a commit in the previous urgent fix PR from me. Ulad, let me know > > > if you want me to do it. > > > > > I do not mind :) So i can drop this patch! > > > > Alright, I created the fix branch at: > > https://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux.git/log/?h=fixes.v7.1 > > And I'm going to throw some tests on it. Will send the pull request > tomorrow. > Cool, then i drop this patch! -- Uladzislau Rezki