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 434463BADB1 for ; Wed, 11 Mar 2026 07:58:26 +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=1773215913; cv=none; b=UxBoKQTRI6yvw/in08WX8wmUUnN8gpgjqVGIV6qyE6ClaGqJ3GgwS5vR3CZny9dUEBwU1GKOcvCvBezXXvjaBiGhJHw4eiFT7LdbwOZaGL9J2hPykwUk6fx1kaaUKiSzo2D6qcFq6Q70R3YDlwrG2z3R92eGTHItHIBvAcqxN2g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773215913; c=relaxed/simple; bh=M+8WdzD2aYCDIaY/Z5Ub32RarrXfCw8D3u4KgO5ntV4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J5P2V3zMZE6fzpD5umjvC7ABE0M239vIgkM70105sGy3Gbws3Tf5X91zz7rDG6k4mGK/bPCb/ta/WVg1Jpct982cS62oNDhnZlW8ZzP191ALWd4eHoU2ych3JAUXsy+ejoAQeQpsRsW2D9yvCKJU42/p9a7NIU6RDmREg7beKYc= 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=hggzsWlY; 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="hggzsWlY" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=WkNx4RBK7t8hlLX34zf9PeF1xZwqHFIKtQtklIpAwWI=; b=hggzsWlYHrSBCuIrYtxnctE0lP gXAe3NuIL0Xjz9Uft2xD8wz3NQfMlvfzvN66/IMeJMjgaPOWYMhsi1sLVyqBIMRxJWOO8/jLP2peE zpPV0RoHWl/ZhuqImNQtvdhJWc259QHTIBerdmMXVaA7zW3GwoNDpVdsZ7M0T9i2OPWymAZuyxupN Cr6ssNYGbJaOSw1cX3Z9rJUGMmn66ooX3EtP0U9EHVhk48bd0M9Qhnbqcr89D4I8bM/GeWSxCzL7N 07KxPEpW8K+60aHQr4Z2cHtgKPkLAc5SSydKqe4J7hUCNiI2KXZ0Izk9dRY1SNDfgN8X6TAm81IWb 36b5xozA==; 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 desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1w0ESW-0000000GJnC-2BKf; Wed, 11 Mar 2026 07:58:24 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 0BC1E300462; Wed, 11 Mar 2026 08:49:45 +0100 (CET) Date: Wed, 11 Mar 2026 08:49:45 +0100 From: Peter Zijlstra To: Jiri Slaby Cc: Thomas Gleixner , LKML , Mathieu Desnoyers , Matthieu Baerts Subject: Re: [patch 1/4] sched/mmcid: Prevent CID stalls due to concurrent forks Message-ID: <20260311074945.GJ606826@noisy.programming.kicks-ass.net> References: <20260310201009.257617049@kernel.org> <20260310202525.969061974@kernel.org> <470f5363-8c84-4061-b8c3-4287d11ea6c3@kernel.org> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <470f5363-8c84-4061-b8c3-4287d11ea6c3@kernel.org> On Wed, Mar 11, 2026 at 08:33:01AM +0100, Jiri Slaby wrote: > Thomas, > > On 10. 03. 26, 21:28, Thomas Gleixner wrote: > > A newly forked task is accounted as MMCID user before the task is visible > > in the process' thread list and the global task list. This creates the > > following problem: > ... > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -4729,8 +4729,12 @@ void sched_cancel_fork(struct task_struc > > scx_cancel_fork(p); > > } > > +static void sched_mm_cid_fork(struct task_struct *t); > > This introduces: > [ 97s] ../kernel/sched/core.c:4711:13: warning: ‘sched_mm_cid_fork’ > used but never defined > [ 97s] 4711 | static void sched_mm_cid_fork(struct task_struct *t); > [ 97s] | ^~~~~~~~~~~~~~~~~ > > on !CONFIG_SCHED_MM_CID configs. (gcc15-15.2.1+git10776-2.3) Indeed. I'll fix it before applying.