From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 36272359A79; Tue, 10 Mar 2026 08:20:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773130843; cv=none; b=AzUNV84CujVAdcrDzYEWy0CIL71qeVhyTEkKrCjNalFvKiqKQLPMedc9DaOuiD3PXYPa0oNuo0/EWeBYY+S6MLlkpjWJQoxlQv7Bu9hkgyyqzynH8O4A7bsfeGRHobQsdPH5hWHo7BGFvFOhOOeNU/L9a8Z8SuBehDuXHY7eGfg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773130843; c=relaxed/simple; bh=Y8GYnKbz4eYcvSaBBRoLhh4UlJAVNjD6eWg7sPSC554=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=Q0m/2Y5bQgAFGPqUewDkW84e8GZNwMb9gvQ/Y2IwSS673adXTkHljs8qhmJZAmhKPOq9EKPuOp1mHj1ecVWkJCJWWSGKIfOHmQ2W8Aj/x2y8IcDeQGGeFl0avIbUeoV7ZGwfFSdT+m35B10dMrZBX6Dtd+5wcutyV6vUihuNXwU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dXGx1vAg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dXGx1vAg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1CF84C2BC86; Tue, 10 Mar 2026 08:20:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773130842; bh=Y8GYnKbz4eYcvSaBBRoLhh4UlJAVNjD6eWg7sPSC554=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=dXGx1vAgQ6gpWEmqvlaJ+M+7ZoQBt6dkfVHgq9hij2SlyuY065+i4AIN4EUc5hNUW C8JtQ6OXCi4oVCOWh0sWtepHWhs5NJTyVc7R/vHaij87yYOozkDneKVBvU7orQbBPE uFiB7pV+OopprIgbRG2ZLpKBI6Z8/eYD9Exi5/Cyg44CKjRylPZnbVr7aZsjORprd6 fIc4c/IRBnro1IKca3Vp7tpdxScTwFQs/LffEBkIJbDhCWpQem6jpFVaOfBzLizQxs Wd5n0geRYGjVIZ366C4ZUFN/88wrgIugEpqkdQ7tuETwT4pVa8xnfofrvWbWpa7t77 a9XT5QjiwjJgg== From: Thomas Gleixner To: Matthieu Baerts Cc: Peter Zijlstra , Jiri Slaby , Stefan Hajnoczi , Stefano Garzarella , kvm@vger.kernel.org, virtualization@lists.linux.dev, Netdev , rcu@vger.kernel.org, MPTCP Linux , Linux Kernel , Shinichiro Kawasaki , "Paul E. McKenney" , Dave Hansen , luto@kernel.org, Michal =?utf-8?Q?Koutn=C3=BD?= , Waiman Long , Marco Elver Subject: Re: Stalls when starting a VSOCK listening socket: soft lockups, RCU stalls, timeout In-Reply-To: <87eclsrtqg.ffs@tglx> References: <863a5291-a636-47d0-891c-bb0524d2e134@kernel.org> <20260302114636.GL606826@noisy.programming.kicks-ass.net> <717310d8-6274-4b7f-8a19-561c45f5f565@kernel.org> <87zf4m2qvo.ffs@tglx> <47cba228-bba7-4e58-a69d-ea41f8de6602@kernel.org> <87tsuu2i59.ffs@tglx> <7efde2b5-3b72-4858-9db0-22493d446301@kernel.org> <87qzpx2sck.ffs@tglx> <20260306152458.GT606826@noisy.programming.kicks-ass.net> <87ldg42eu7.ffs@tglx> <87h5qr2rzi.ffs@tglx> <87eclu3coa.ffs@tglx> <87v7f61cnl.ffs@tglx> <57c1e171-9520-4288-9e2d-10a72a499968@kernel.org> <87pl5ds88r.ffs@tglx> <0ae4d678-5676-4523-bae3-5ad73b526e27@kernel.org> <87eclsrtqg.ffs@tglx> Date: Tue, 10 Mar 2026 09:20:38 +0100 Message-ID: <87bjgwrt7t.ffs@tglx> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Tue, Mar 10 2026 at 09:09, Thomas Gleixner wrote: > On Mon, Mar 09 2026 at 13:23, Matthieu Baerts wrote: > So the only circumstances where mm_cid_do_fixup_tasks_to_cpus() fails to > do that are: > > 1) task->mm != mm. > > or > > 2) task is not longer in the task list w/o going through do_exit() or 3) task->mm_cid.active == 0 again w/o going through do_exit() > How the heck is either one of them possible? > > Just for the record. The picture Jiri decoded from the VM crash dump is > exactly the same. One task is not listed. > > Confused > > tglx