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Tue, 22 Sep 2026 05:28:54 -0700 (PDT) Date: Tue, 22 Sep 2026 14:28:52 +0200 From: Petr Mladek To: Bradley Morgan Cc: Andrew Morton , Jinchao Wang , Craig Lamparter , Wim Van Sebroeck , Guenter Roeck , linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 6/6] panic: kill the "buffer unavailable" redirect fallback Message-ID: References: <20260916182957.7788-1-brads@mainlining.org> <20260916182957.7788-7-brads@mainlining.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 In-Reply-To: <20260916182957.7788-7-brads@mainlining.org> On Wed 2026-09-16 18:29:57, Bradley Morgan wrote: > The redirect buffer is a disgusting terrible hack. panic_force_buf is > kmalloc'ed in a late_initcall, and until then the redirect delivers > this as the panic message: > > Redirected panic (buffer unavailable) > > The whole point of the redirect is to hand the panic message to the > target CPU, so the crash kernel boots knowing it panicked and not why. > And that window is the entire boot, from the early_param to the > late_initcall, which is exactly when you most want the message. > > Make it a static 1KB buffer and kill the initcall. The cost is 1KB of > .bss in SMP crash dump builds, and it is only ever touched when > panic_force_cpu= is set anyway. The local msg variable is gone too, > the buffer goes directly to panic_smp_redirect_cpu(). > > Suggested-by: Petr Mladek > Signed-off-by: Bradley Morgan Look good to me: Reviewed-by: Petr Mladek Best Regards, Petr