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 160C12F3C37 for ; Mon, 30 Mar 2026 14:40:17 +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=1774881620; cv=none; b=S8fm/WXWi2CjXh5HZ03R3xmPMFNzxSxxvxEVf5xx5Z1/RpvhO6yv1P7t+xMVsKlx3bSudzLkbCKmC7L+WnEV21ISphSiGWs1N7LC9zvsj9f6KlkIkpVTXREUm7XYSjQ1Mww6erIGcmSkDnhLBwLNl4h2D70ojiirDO5VqzE727Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774881620; c=relaxed/simple; bh=wFlTDQDw57bJk2DoYuvKV5Cwez9FllyfR7Z0Qke4TBo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oXdkA0tBi6KpEQMxiMjwdo/2LZOv8u21NvarBN0b4O5vi7QPDYGtfUZ6snBJ6eIGgGESdysr2lbtWcHNFFCjaYYxTmTqTVF3xQG+DR1hVcgasC+4sCZw72J18ZRN6noVjIyJabF5J97kwauPEKrPMQwGZh9T2rLD1uONMrhsYAA= 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=XRJ4h1cL; 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="XRJ4h1cL" 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=WE2TLcv6NYsOn3Lb7vD0Dsk2R7h/XS9VJdAk/LrUly0=; b=XRJ4h1cLCfao0uuvLB6trDxcY8 JAp/Gw5ZNA8rFw7LJY7IIgsoJNtvG4H+KoAFgmosmNOWLNVg8GOUjpUfmBoXpKkAujEL2UAMRWpag FS8LGFpxFhTYF840BIgGjNIU3X/2gauFVf3huCuX00HI8a0bNkqBrFh2MfI/I0vTnfQraXz+etBpw 3EN1dSKRHRjbpcgCR5t8i2KPjzCZNK4n7/M2Ep8lTmLSxM25jbe3r6hgb47seiVWONYLUnpNM8OCY fmdedvINO9WoYFolEquRkzHEQq/XxP6eQkOClnbnz3WlzcpH5fqoRvPCGU4OkXkFuGfi7tjI43ZBy hPaokmmQ==; 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 1w7Dmh-00000006otm-0eUh; Mon, 30 Mar 2026 14:40:07 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id EC406300302; Mon, 30 Mar 2026 16:40:05 +0200 (CEST) Date: Mon, 30 Mar 2026 16:40:05 +0200 From: Peter Zijlstra To: K Prateek Nayak Cc: John Stultz , mingo@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org, wangtao554@huawei.com, quzicheng@huawei.com, dsmythies@telus.net, shubhang@os.amperecomputing.com, Suleiman Souhlal Subject: Re: [PATCH v2 1/7] sched/fair: Fix zero_vruntime tracking Message-ID: <20260330144005.GP3738786@noisy.programming.kicks-ass.net> References: <20260219075840.162631716@infradead.org> <20260219080624.438854780@infradead.org> <20260330101018.GN3738786@noisy.programming.kicks-ass.net> <73dab51a-650f-4c82-9e73-13236b2a26c2@amd.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: <73dab51a-650f-4c82-9e73-13236b2a26c2@amd.com> On Mon, Mar 30, 2026 at 08:07:06PM +0530, K Prateek Nayak wrote: > Hello Peter, > > On 3/30/2026 3:40 PM, Peter Zijlstra wrote: > > This means, that if the two tasks playing leapfrog can reach the > > critical speed to reach the overflow point inside one tick's worth of > > time, we're up a creek. > > > > If this is indeed the case, then the below should cure things. > > I have been running with this for four hours now and haven't seen > any splats or crashes on my setup. I could reliably trigger the > warning from __sum_w_vruntime_add() within an hour previously so > it is safe to say I was hitting exactly this. > > Feel free to include: > > Tested-by: K Prateek Nayak Ha!, excellent. Thanks!