From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 DF8E837C900 for ; Tue, 3 Mar 2026 19:30:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772566205; cv=none; b=YkMjnC0KyLA2w8uzZIwOpzXoI2vkUwih3ybiAdHCHKqPxNpSJ1IW4JmIkNfRBoQ0zFOjOZel31XD6ycCPNU4e7jxnMSts26i4B2T69zxBbGhgoTzCAcboh1gTt1yQ8LR7rdW/1MDHF9BC0tx71uQ4e4eWXxv0QVHEy5QuQwEl0c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772566205; c=relaxed/simple; bh=snNIbTuDsGMpDt2aEOsRVKxjzPdadhHIe085YU37mdA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WEAraMkjQVH1f8nK5aBViX28MWI3KpcJXfmjZ1Xrr6j1ri8DBAPgp03kBTopv4M59Ylrl7YQTaC7u1/d7+SSggxAdBgZqdXflGOIva/6jHVQqLAIb9DVivNc3H1OA/lKUkKJKIa5gjg1eQo/OtPeH5Z70SOVgVjWVq0r1mKyy90= 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=rR52UiaK; arc=none smtp.client-ip=90.155.50.34 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="rR52UiaK" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=snNIbTuDsGMpDt2aEOsRVKxjzPdadhHIe085YU37mdA=; b=rR52UiaKzthjkPuUhli8V9wGRX x8ofzq9aKbKO/Wvx3dJgqyo0zncyRvdi6mJmZJFkSe64VohZ01Qoz9+WaHVVjjLCWODVj9iGtZKTs IKZDvsrb9cgJ39H971PKMXx3/+RKVJRGXbq8n8vN+iV+kizHDkyBhPPyw95mS07vPZqlsj9Fd32HF 9likpfA931rM0WpCvugf/3tpoVABCMMR3QfEPJ3dMeHbH/A8UDtLKLSEXJkLdZR2dzqgJi/YgbPO/ aWYm+KcowOIL2NCKjoPVZTgPm0gCalX+ZSyePFFu8VZIc44feysmGjXwmxI4tMp+4eIyRhmKSjHoz AaZZTZ/Q==; Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxVRK-0000000C4FO-3N15; Tue, 03 Mar 2026 19:29:54 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id BF055300666; Tue, 03 Mar 2026 20:29:53 +0100 (CET) Date: Tue, 3 Mar 2026 20:29:53 +0100 From: Peter Zijlstra To: "Herton R. Krzesinski" Cc: linux-kernel@vger.kernel.org, frederic@kernel.org, mingo@kernel.org, paulmck@linux.vnet.ibm.com, tglx@linutronix.de, anna-maria@linutronix.de, kyin@redhat.com, jaeshin@redhat.com Subject: Re: [RFC] Processing of raised_list can stall if an IPI/interrupt is missed Message-ID: <20260303192953.GM1395266@noisy.programming.kicks-ass.net> References: <20260303190715.935867-1-herton@redhat.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: <20260303190715.935867-1-herton@redhat.com> On Tue, Mar 03, 2026 at 04:07:15PM -0300, Herton R. Krzesinski wrote: > Or may be it's not worth changing this since this is rare and missed self IPI should > not be expected? IPIs going missing is certainly unexpected; although kernel/smp.c has much debugging crud for similar scenarios (AFAIK all of them related to virt). If IPIs go missing your system *will* go funny in one way or another. I'm not totally against building in some fallback, but we should definitely consider it dodgy/buggy if we do detect one has gone walk-about.