From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 7BD3122091 for ; Mon, 29 Apr 2024 11:05:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714388706; cv=none; b=Jc5qUIbAv0TpkIorMzFDPN5Lb15aFPJIVnME4UzcKPRxrkZr2VdExkIdvqaXEBQzEphjyozROdU/VQ/lu5WvLvWgnGGwsitMBkzEb92peSraNenU8NqZlld+YdZj8BNqn3aITUkD9OC1FgTNh3cnZvYnomYk71Uz6R8psr4vIaE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714388706; c=relaxed/simple; bh=sTSSyBkKD7YDBb5NDHQWR7yiAGxYXMmKFxKGAunMYug=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=HKSWwQs1ftLqXS0AjxtbY91V8cWLbPCHp3Dd8xvSZav/7fE5rzSTYX+jCz/kNsPB1kfbsyR6ds8eAHeQWvFapM6renq+6jZQ1lwySblNNjzLZweGVzyygesG/pHtmZ7rkZaf+HhZawU3ScmWcjh3iYgpP74LtnFDdg7uT3uP+D4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=H4zF/jeM; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="H4zF/jeM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1714388704; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6VS08W4Uz8/bxiSCCoDd/kVVFCwVeCdJq9V0dytDy1w=; b=H4zF/jeM5ipBCwAqiYhNhYf/LPGMiHyZDGIOymKP0nUorR62QOY1fzNHUqdmerSKY+po6Q QZwOBdmJi1U/TmqZrXyj4/B4IN0ggmkiZTcce+CZ+Lg6Yf5LeLtxx8Mbf6oBXtX3AA7mCK dBwi+W43g7q1YjGGDdLhXQjejINUvi0= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-665-uwHYflRGOua0fkQXp25JRA-1; Mon, 29 Apr 2024 07:04:58 -0400 X-MC-Unique: uwHYflRGOua0fkQXp25JRA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5C07D380621F; Mon, 29 Apr 2024 11:04:57 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.143]) by smtp.corp.redhat.com (Postfix) with SMTP id D4D7D1C060D0; Mon, 29 Apr 2024 11:04:54 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 29 Apr 2024 13:03:32 +0200 (CEST) Date: Mon, 29 Apr 2024 13:03:28 +0200 From: Oleg Nesterov To: Frederic Weisbecker Cc: LKML , "Paul E. McKenney" , Boqun Feng , Joel Fernandes , Neeraj Upadhyay , Uladzislau Rezki , Zqiang , rcu , "Eric W . Biederman" , Lai Jiangshan Subject: Re: [PATCH] Revert "rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()" Message-ID: <20240429110328.GB1101@redhat.com> References: <20240425142404.19927-1-frederic@kernel.org> Precedence: bulk X-Mailing-List: rcu@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: <20240425142404.19927-1-frederic@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 On 04/25, Frederic Weisbecker wrote: > > This reverts commit 28319d6dc5e2ffefa452c2377dd0f71621b5bff0. The race > it fixed was subject to conditions that don't exist anymore since: > > 1612160b9127 ("rcu-tasks: Eliminate deadlocks involving do_exit() and RCU tasks") > > This latter commit removes the use of SRCU that used to cover the > RCU-tasks blind spot on exit between the tasklist's removal and the > final preemption disabling. The task is now placed instead into a > temporary list inside which voluntary sleeps are accounted as RCU-tasks > quiescent states. This would disarm the deadlock initially reported > against PID namespace exit. > > Signed-off-by: Frederic Weisbecker > --- > include/linux/rcupdate.h | 2 -- > kernel/pid_namespace.c | 17 ----------------- > kernel/rcu/tasks.h | 16 +++------------- > 3 files changed, 3 insertions(+), 32 deletions(-) LGTM. FWIW, Reviewed-by: Oleg Nesterov