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 CCDE622A7E9; Wed, 5 Feb 2025 10:16:12 +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=1738750574; cv=none; b=RQCZPkAaUyU5u92YRWPoYElsPC2OVN+hl2THmqztD4jxBieknsm9JyNRKxfqudeIi6JOu8UtOZ1zfgbNA6KtRzAcyfGTCxbW9Vm8SbODyKL7huZJHa6cMvg7sV7MYMVuxYLBlcaat7qYKdtDcnbhFDtUfs8ZHTTcUX1B8Bj4Fes= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738750574; c=relaxed/simple; bh=A1COUhFMiYkZ6jWZ4rEG5AaYuGBBBYVEG3AG8lJPcvU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GLTpJlKQYvuULQW5/J3ykw9LO0mwHB/Fi6533SlShNjydylkBTSY6SnGcM8P3oXBn8KM2qA6Y5td+9aqnW/JVYdpA8aJZhiwuh0Ci0jJSS/aTQjW6JJHXvNUcuw+vvemus7y5I90pH2wJUxQlJuu1FasGDRuNruJQUVSTl87VHM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=Ma/tp+dD; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="Ma/tp+dD" 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=9qXcAANLcizackECdOPJD2ARkgdD5l7NyBSWXT9HO1A=; b=Ma/tp+dDFNvt9ACHB9KS8/jzjV 9Tg5pLwrMjO/fDEYREdAxAO2M+icsWv7IYG9possNI3spAyBSM/BnI6zldcwfvJRwpvnA8zm5pfEb SGFdGEq6q/llKTT+VWcbKjM8F/IWhZLJxnvWOxqeB9VLgYo1gmvZO3aR59S/sJH/JTp0oip1BFk15 gpRLUCpVeH8vX+kCTvhMO3hJL4oF4eH35/COestyz92i2M4lyB8MxHdYLxbTp6ajYipk5tirYmEP4 9XRv0FL0jPmf4jlspF3bVcyedulflMfKzH3eWFvehPu5Uhok1mxQyGVzZIs5IsGiKCRGaKRhVJ63W uk8I4v6Q==; Received: from 77-249-17-89.cable.dynamic.v4.ziggo.nl ([77.249.17.89] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tfcRt-0000000GbiU-3UNP; Wed, 05 Feb 2025 10:16:02 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 8C4C03002F0; Wed, 5 Feb 2025 11:16:00 +0100 (CET) Date: Wed, 5 Feb 2025 11:16:00 +0100 From: Peter Zijlstra To: K Prateek Nayak Cc: Naman Jain , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , stable@vger.kernel.org, linux-kernel@vger.kernel.org, Steve Wahl , Saurabh Singh Sengar , srivatsa@csail.mit.edu, Michael Kelley Subject: Re: [PATCH v3] sched/topology: Enable topology_span_sane check only for debug builds Message-ID: <20250205101600.GC7145@noisy.programming.kicks-ass.net> References: <20250203114738.3109-1-namjain@linux.microsoft.com> <20250205095506.GB7145@noisy.programming.kicks-ass.net> <0835864f-6dc5-430d-91c0-b5605007d9d2@amd.com> Precedence: bulk X-Mailing-List: stable@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: <0835864f-6dc5-430d-91c0-b5605007d9d2@amd.com> On Wed, Feb 05, 2025 at 03:43:54PM +0530, K Prateek Nayak wrote: > Hello Peter, > > Thank you for the background! > > On 2/5/2025 3:25 PM, Peter Zijlstra wrote: > > On Wed, Feb 05, 2025 at 03:18:24PM +0530, K Prateek Nayak wrote: > > > > > Have there been any reports on an x86 system / VM where > > > topology_span_sane() was tripped? > > > > At the very least Intel SNC 'feature' tripped it at some point. They > > figured it made sense to have the LLC span two nodes. > > > > But I think there were some really dodgy VMs too. > > > > But yeah, its not been often. But basically dodgy BIOS/VM data can mess > > up things badly enough for it to trip. > > Has it ever happened without tripping the topology_sane() check first > on the x86 side? That I can't remember, sorry :/