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Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uy6Y7-0000000D6F6-0hE9; Mon, 15 Sep 2025 10:35:07 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id A7674302E03; Mon, 15 Sep 2025 12:35:06 +0200 (CEST) Date: Mon, 15 Sep 2025 12:35:06 +0200 From: Peter Zijlstra To: Will Deacon Cc: Yunhui Cui , akpm@linux-foundation.org, catalin.marinas@arm.com, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, kees@kernel.org, masahiroy@kernel.org, aliceryhl@google.com, ojeda@kernel.org, thomas.weissschuh@linutronix.de, xur@google.com, ruanjinjie@huawei.com, gshan@redhat.com, maz@kernel.org, suzuki.poulose@arm.com, zhanjie9@hisilicon.com, yangyicong@hisilicon.com, dianders@chromium.org, gautam@linux.ibm.com, arnd@arndb.de, zhao.xichao@vivo.com, rppt@kernel.org, lihuafei1@huawei.com, coxu@redhat.com, jpoimboe@kernel.org, yaozhenguo1@gmail.com, luogengkun@huaweicloud.com, max.kellermann@ionos.com, tj@kernel.org, wangjinchao600@gmail.com, yury.norov@gmail.com, thorsten.blum@linux.dev, x86@kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH] watchdog: remove HARDLOCKUP_DETECTOR_PERF Message-ID: <20250915103506.GA3245006@noisy.programming.kicks-ass.net> References: <20250915035355.10846-1-cuiyunhui@bytedance.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Sep 15, 2025 at 11:26:09AM +0100, Will Deacon wrote: > | If all CPUs are hard locked up at the same time the buddy system > | can't detect it. > > Ok, so why is that limitation acceptable? It looks to me like you're > removing useful functionality. Yeah, this. I've run into this case waaay too many times to think it reasonable to remove the perf/NMI based lockup detector.