From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7A796379961 for ; Thu, 8 Jan 2026 07:49:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767858575; cv=none; b=Ew3VXzCxM6AqrHSAWwfHCYtq/sKUeb6NztkwBa7fYq2vu6SjfxXqUwQQ145H179Nn9yGhWZ3WzzRyQJnLWlmQM1b8NxM8tG9LFU0zuxKAmA5nJBHlf+awPs1smoTmPkIag5A1JOgWaOc/Ea1RT87Hgs9iMEiQyepx70gSCI0F6E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767858575; c=relaxed/simple; bh=NWeQoBtYC0Y7+eIWhSwdU6wusNEWXjDt+X141zOZybQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QBorWvdE5vnmwkfbeD3qwPoE3nxTb8XtX2DJV9crEjI7+5TJk1radm5FGSsMLklg6dXqP/3CXjNyuAIW3m4y8CBx3GHihN0CAdySdKJxK/KKJBT08P5DJSi0uV2wTVX01wsGWZ3rfDvH9GeQeHrkNNJBu+ximtO1AOGXLNfj5mA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=lDg3MlBU; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="lDg3MlBU" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=D49AENJfl4NI0ItDjx8iQWqzaSzRcqCYxmCxEK2HoZY=; b=lDg3MlBUsGicwjYrGlU/E8r6wx 8bhPb4sP2+UwCRkIspVRIseLvNk2RaRfboRunHmZM7FdqlNpmzSXizAhEbyp7N/nUfV/WCQtVdF2H C4HMzV50e8ddpm2yKH0NqDD4VAfVPkpMUYo2Jc90dS6Qrw9CFUhEBSe1wyCPExGFKrwqtXKCu5ri6 XjhYsAzBQL+6iN+dzlp0jKM7Z0wCGWAr26hwomTUfRPccFvtnCG9Sq9bfcuQ4Gj2Cb3fHIMWw3pcf f9HMS5/8LXaGXRW4Pmg0lDW+3aG0Ppp9EQVW+w4i/2DT/aBDeYVU5HFUhN6UB8sP/Gy/x5FBhRBL/ Xy5AojFg==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vdklg-0000000CfvE-1W1j; Thu, 08 Jan 2026 07:49:16 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id C975830031E; Thu, 08 Jan 2026 08:49:15 +0100 (CET) Date: Thu, 8 Jan 2026 08:49:15 +0100 From: Peter Zijlstra To: Baoquan He Cc: Pnina Feder , akpm@linux-foundation.org, pmladek@suse.com, linux-kernel@vger.kernel.org, lkp@intel.com, mgorman@suse.de, mingo@redhat.com, rostedt@goodmis.org, senozhatsky@chromium.org, tglx@linutronix.de, vkondra@mobileye.com Subject: Re: [PATCH v4] panic: add panic_force_cpu= parameter to redirect panic to a specific CPU Message-ID: <20260108074915.GE272712@noisy.programming.kicks-ass.net> References: <20260105081808.1771473-1-pnina.feder@mobileye.com> <20260107215659.3619730-1-pnina.feder@mobileye.com> 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: On Thu, Jan 08, 2026 at 11:11:50AM +0800, Baoquan He wrote: > On 01/07/26 at 11:56pm, Pnina Feder wrote: > > Some platforms require panic handling to execute on a specific CPU for > > crash dump to work reliably. This can be due to firmware limitations, > > Thanks for fixing this. Could you kindly reveal which platform this > issue is from? > > > interrupt routing constraints, or platform-specific requirements where > > only a single CPU is able to safely enter the crash kernel. > > > > Add the panic_force_cpu= kernel command-line parameter to redirect panic > > execution to a designated CPU. When the parameter is provided, the CPU > > that initially triggers panic forwards the panic context to the target > > CPU via IPI, which then proceeds with the normal panic and kexec flow. > > > > If the specified CPU is invalid, offline, or a panic is already in > > progress on another CPU, the redirection is skipped and panic continues > > on the current CPU. > > What if both the original CPU and specified CPU are not able to function > well on panic jumping? The crash dumping will fail in this case? Yes.