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 426D540DFD2; Tue, 10 Mar 2026 13:47:40 +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=1773150460; cv=none; b=dY77Sz8OwaSkqGLiWTn10XgYNwDnkZLN+ZhEzclNN6IiaHEgimpPKkP/fgRVpuCW5ZnUiee3ba7pXLWqg9FOVkEfuRsn5IbEtD8oPZsEsANfxKjJ61hDIq92YmP+chY3UqzWZy44ghhUuhykZ0x9gRbnt1zQT9wXESHOmv4xIAM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773150460; c=relaxed/simple; bh=2+IBJ8l0YArk9c6MpfP8rThaUSBwcqM1jZp+Xt9Q7uQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=eJQOMkKFK9rawd7kqqDGYo3NEF7T7/Yxadbf0+S+zkNk0D3RW1YOnZ11H2+6nH7iRCl4LLRdVMPwzxkJSuLoyJcNehil0faicn5J3jpaCymo1zbCRJzbZwezTIJhvr2QRaHbwFUiHFJ8c0So/FbOkCiCTOIUiFAChmXOLK/66OI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f8rkrF9/; 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="f8rkrF9/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14F03C19423; Tue, 10 Mar 2026 13:47:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773150459; bh=2+IBJ8l0YArk9c6MpfP8rThaUSBwcqM1jZp+Xt9Q7uQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=f8rkrF9/ZK/NwePW8e7bG5OrZ7E3hPqK4XLnXB+19kaG/qPwUE/jGeWJtrt9sXA+c WRqkAfNhAaKHFwChsql8pCUYnojyznTHIwVrTTjSJzdwCR71LlodMbMhVGy4ao0A4S kPSl3eEBZEIKXIK6k13Wokh86en03vtdxNU5oQhuo1YyBYSYWP7D/SY6AkAUUS8Z8T mdn74yJTLwQYsJBN/XwYSuAZx9K2Z1ed26Yl9DQPdl5NAUAvNVbOiljQeHfT0T5G/s p0VFQfDZpZ3vjXnMYqCcj2gZBcmbBxA4G+VYnmitBwSYv0i9EuSAGd8Gu/Q5Ee6PyQ yfRy5/HywG+hQ== From: Thomas Gleixner To: Matthieu Baerts , Peter Zijlstra Cc: 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: References: <87v7f61cnl.ffs@tglx> <57c1e171-9520-4288-9e2d-10a72a499968@kernel.org> <87pl5ds88r.ffs@tglx> <0ae4d678-5676-4523-bae3-5ad73b526e27@kernel.org> <87eclsrtqg.ffs@tglx> <76e2b909-98db-49de-a8eb-f6f0a192f630@kernel.org> <878qc0rofr.ffs@tglx> <874imorobw.ffs@tglx> <4cad1b9a-e157-427b-9896-cf54cf6fba36@kernel.org> <20260310115433.GV1282955@noisy.programming.kicks-ass.net> <87y0jzrhqn.ffs@tglx> Date: Tue, 10 Mar 2026 14:47:35 +0100 Message-ID: <87v7f3re2w.ffs@tglx> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Tue, Mar 10 2026 at 14:40, Matthieu Baerts wrote: > On 10/03/2026 13:28, Thomas Gleixner wrote: > > (...) > >> I've updated the debug patch and removed the @users conditionals so it >> keeps searching. So it should find that magic 73. > > It looks like it does, thank you! I just tried this new debug patch, and > I managed to boot 100 times without issues, while before I was getting > it after max 20 attempts. I left the test running to boot up to 1000 > times, just in case. Now that I actually understood the problem, I was able to write a reproducer which triggers the issue 100% reliable. The debug patch does cure it and it does the right thing. I have a better version of that in testing right now which avoid all that flaky accounting and especially in the vfork() case the full tasklist walk. I'll send out a complete patch series with changelogs etc. later. Thanks a lot for your patience and invaluable help. Very appreciated! tglx