From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-190f.mail.infomaniak.ch (smtp-190f.mail.infomaniak.ch [185.125.25.15]) (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 DE4A21487E7 for ; Tue, 4 Jun 2024 16:07:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.125.25.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717517226; cv=none; b=ZXYf96USNUUtKWQOnTj1d4eSDaqS8Kml4ZznSU87flxX4EnI78MJTr6RjxYr4VG9bF6rc8PtwoM74GOIa6jNg98TscAkKwN/6YP5VLDZv6LWpfYiSFNL6LIcS3NDgcx8vxIU+YMibw9GSl+Zv6ckaYQ0ykQ5TRNropWTsX5TIPE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717517226; c=relaxed/simple; bh=LiSw4cTkRlKkl50Td/1EOWuYousa7uj5W+u2v+62BuQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=scU4YaDR0zRJepYovtYNzbBiNAeeKBy22UojSO4gqlb0LqZJvtTamg+Hd1O6WAMmA6zNuj3Rj95VIVim2m+7Zi2Y8hNBYZ9J+jnVttWBy1lGalyHwdQ/DQlEvaECdw1gHYWNdAMBVinBL01WY3ayujUwPq/khFmC5IAK/THFrKQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net; spf=pass smtp.mailfrom=digikod.net; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b=hFtnqX57; arc=none smtp.client-ip=185.125.25.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=digikod.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b="hFtnqX57" Received: from smtp-4-0001.mail.infomaniak.ch (smtp-4-0001.mail.infomaniak.ch [10.7.10.108]) by smtp-4-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4VtwTB71FQzR2Y; Tue, 4 Jun 2024 18:06:54 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1717517214; bh=aNLMmrtRqyR3S0obQrH4DObn3P8MphMPMTJP3cciKvM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hFtnqX57SJl/4Fh9aQvCi1KoonGg5N4DjhRPZByVGizbDmtLtvsZMh03LYRvUKPzh oluqoBSNi6W59lxCYFr6Va/1Ifx551otm6KY9D1p5DEAHJdc3nW+DCr57SHC9r3grY pCgBICWchLUQPM8ecx8uhp9WxlYZ68yjuYOOyKQc= Received: from unknown by smtp-4-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4VtwT80YykzC0N; Tue, 4 Jun 2024 18:06:51 +0200 (CEST) Date: Tue, 4 Jun 2024 18:06:48 +0200 From: =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= To: Mark Brown Cc: Christian Brauner , Greg Kroah-Hartman , Jakub Kicinski , Kees Cook , Linus Torvalds , Sasha Levin , Sean Christopherson , Shengyu Li , Shuah Khan , Shuah Khan , Bagas Sanjaya , Brendan Higgins , David Gow , "David S . Miller" , Florian Fainelli , =?utf-8?Q?G=C3=BCnther?= Noack , Jon Hunter , Ron Economos , Ronald Warsow , Stephen Rothwell , Will Drewry , kernel test robot , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, netdev@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v7 04/10] selftests/harness: Fix interleaved scheduling leading to race conditions Message-ID: <20240604.KaT6shae5eip@digikod.net> References: <20240511171445.904356-1-mic@digikod.net> <20240511171445.904356-5-mic@digikod.net> <9341d4db-5e21-418c-bf9e-9ae2da7877e1@sirena.org.uk> <187423fb-ec78-4318-9da0-5b27df62b71f@sirena.org.uk> <9eb1e48e-b273-475a-9740-52deedf11ee2@sirena.org.uk> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <9eb1e48e-b273-475a-9740-52deedf11ee2@sirena.org.uk> X-Infomaniak-Routing: alpha On Mon, Jun 03, 2024 at 06:22:32PM +0100, Mark Brown wrote: > On Mon, Jun 03, 2024 at 05:27:52PM +0100, Mark Brown wrote: > > On Mon, May 27, 2024 at 08:07:40PM +0100, Mark Brown wrote: > > > > This is now in mainline and appears to be causing several tests (at > > > least the ptrace vmaccess global_attach test on arm64, possibly also > > > some of the epoll tests) that previously were timed out by the harness > > > to to hang instead. A bisect seems to point at this patch in > > > particular, there was a bunch of discussion of the fallout of these > > > patches but I'm afraid I lost track of it, is there something in flight > > > for this? -next is affected as well from the looks of it. Thanks for the heads up. I warned about not being able to test everything when fixing kselftest last time, but nobody show up. Is there an easy way to run most kselftests? We really need a (more accessible) CI... > > > FWIW I'm still seeing this on -rc2... > > AFAICT this is due to the switch to using clone3() with CLONE_VFORK I guess it started with the previous vfork() that was later replaced with CLONE_VFORK. > to start the test which means we never even call alarm() to set up the > timeout for the test, let alone have the signal for it delivered. I'm a > confused about how this could ever work, with clone_vfork() the parent > shouldn't run until the child execs (which won't happen here) or exits. > Since we don't call alarm() until after we started the child we never > actually get that far, but even if we reorder things we'll not get the > signal for the alarm if the child messes up since the parent is > suspended. > > I'm not clear what the original race being fixed here was but it seems > like we should revert this since the timeout functionality is pretty > important? It took me a while to fix all the previous issues and it would be much easier to just fix this issue too. I'm working on it.