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 2114923EAB3; Wed, 28 Jan 2026 08:46:50 +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=1769590014; cv=none; b=Qgg4DzK3umf3zm9EIqz9xi6S6sbeuC4u2S6bA+6Eixnpv3ZHSLV/mAumaAniHkJadObiCm7OJNRajWrEt5RMLt3QT3J/ZKCqsI4PtFaHV7FLIfjoiIwkYmw1U9cu6fVl7TisCiqtusbXg53r2Eu3xGxhmcmtOOO/FZ4LpTuHZCA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769590014; c=relaxed/simple; bh=+XP7TKLKMP2iI43Cq419V2HCtzSjoQCGqsdjvG4LxYs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lXEhv46VFucex/a64MrPWOk0k5U7+E8XBqfhhcGrZ6NO85+WYe97/WKzPXM7rDJRrkgJB35Q1IBNhfrJzVZavqZNdLPEQbP6w1zytACBJA8tTmB0UFVH0ksNj/+yqqW447LqFdV14VW203JUV56LmYnT3P2BjOMuoWDoR4xtUsI= 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=CTaO7UHu; 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="CTaO7UHu" 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=ayBrCzFssGZ1vK+gQhCWjuWjGXFaXI8f7cM+Qt4R5zg=; b=CTaO7UHu4vz4tlMZz6OZSKzlPg S3vYo3dGdgqKxi5K4mPUVmGAOQxGWbO/dCV6LnAPXY2SMghsnAF+3ggFSLDA9knn7A+fd2M7NYLat QEhJnPeGjQwz3xD67uBPNpaskHSttt+jA5c//UJYwe3fIBH6hglP+RHwfLf21rHgZxk/qoKXthKan 1sAiF51BWxAGWg9i3fEUTCjr1e9caKh6vgIlxF9l9wL5d+shmx2O8sbnGjRgDel9pUmqPSh6Il9FA NvxTt6CADDqg9z1UeHJ5jY2fTldO6RyBHoWObdcq+7esGgTY90QT3Lz39qnSwj1uWwpmK7/kDBb9Q dmioE3vw==; 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 1vl1Bz-00000008lvA-42T7; Wed, 28 Jan 2026 08:46:28 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 51C8E300754; Wed, 28 Jan 2026 09:46:16 +0100 (CET) Date: Wed, 28 Jan 2026 09:46:16 +0100 From: Peter Zijlstra To: Ihor Solodrai Cc: Thomas Gleixner , LKML , Gabriele Monaco , Mathieu Desnoyers , Michael Jeanson , Jens Axboe , "Paul E. McKenney" , "Gautham R. Shenoy" , Florian Weimer , Tim Chen , Yury Norov , Shrikanth Hegde , bpf , sched-ext@lists.linux.dev, Kernel Team , Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Puranjay Mohan , Tejun Heo Subject: Re: [patch V5 00/20] sched: Rewrite MM CID management Message-ID: <20260128084616.GD3372621@noisy.programming.kicks-ass.net> References: <20251119171016.815482037@linutronix.de> <2b7463d7-0f58-4e34-9775-6e2115cfb971@linux.dev> Precedence: bulk X-Mailing-List: bpf@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: <2b7463d7-0f58-4e34-9775-6e2115cfb971@linux.dev> On Tue, Jan 27, 2026 at 04:01:11PM -0800, Ihor Solodrai wrote: > On 11/19/25 9:26 AM, Thomas Gleixner wrote: > > This is a follow up on the V4 series which can be found here: > > > > https://lore.kernel.org/20251104075053.700034556@linutronix.de > > > > The V1 cover letter contains a detailed analyisis of the issues: > > > > https://lore.kernel.org/20251015164952.694882104@linutronix.de > > > > TLDR: The CID management is way to complex and adds significant overhead > > into scheduler hotpaths. > > > > The series rewrites MM CID management in a more simplistic way which > > focusses on low overhead in the scheduler while maintaining per task CIDs > > as long as the number of threads is not exceeding the number of possible > > CPUs. > > Hello Thomas, everyone. > > BPF CI caught a deadlock on current bpf-next tip (35538dba51b4). > Job: https://github.com/kernel-patches/bpf/actions/runs/21417415035/job/61670254640 > > It appears to be related to this series. Pasting a splat below. > > Any ideas what might be going on? That splat is only CPU2, that's not typically very useful in a lockup scenario.