From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [PATCH v7 09/10] memcg: enable accounting for tty-related objects Date: Tue, 27 Jul 2021 08:09:09 +0200 Message-ID: References: <6f21a0e0-bd36-b6be-1ffa-0dc86c06c470@virtuozzo.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1627366151; bh=12GRn6/Ruq7Tv7H9GUSviN2q+t9S6N5v5Lcy9EzpXmQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=emP7gDqUhtszgWgqPv4PuPidiHYIboQejjWQj1WwmXBBwvX2vQwilrXcDdq6L4dCP vS+u7HfpvxdnYJ5eANYPI6cxxf4iV3aoRNPm1cGRaDJdBMKJu8cn3i3MMbeR/77yGH MTFdgXW5aqONYf6x3XCDALR0tCf3+FzZ9GaB91n4= Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Vasily Averin Cc: Andrew Morton , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Michal Hocko , Shakeel Butt , Johannes Weiner , Vladimir Davydov , Roman Gushchin , Jiri Slaby , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Tue, Jul 27, 2021 at 08:34:14AM +0300, Vasily Averin wrote: > At each login the user forces the kernel to create a new terminal and > allocate up to ~1Kb memory for the tty-related structures. > > By default it's allowed to create up to 4096 ptys with 1024 reserve for > initial mount namespace only and the settings are controlled by host admin. > > Though this default is not enough for hosters with thousands > of containers per node. Host admin can be forced to increase it > up to NR_UNIX98_PTY_MAX = 1<<20. > > By default container is restricted by pty mount_opt.max = 1024, > but admin inside container can change it via remount. As a result, > one container can consume almost all allowed ptys > and allocate up to 1Gb of unaccounted memory. > > It is not enough per-se to trigger OOM on host, however anyway, it allows > to significantly exceed the assigned memcg limit and leads to troubles > on the over-committed node. > > It makes sense to account for them to restrict the host's memory > consumption from inside the memcg-limited container. > > Signed-off-by: Vasily Averin > Acked-by: Greg Kroah-Hartman > --- > drivers/tty/tty_io.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) As this is independant of all of the rest, I'll just take this through my tree now so that you do not have to keep resending it. thanks, greg k-h From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE24BC432BE for ; Tue, 27 Jul 2021 06:09:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAA2E61107 for ; Tue, 27 Jul 2021 06:09:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235632AbhG0GJL (ORCPT ); Tue, 27 Jul 2021 02:09:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:37436 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235557AbhG0GJK (ORCPT ); Tue, 27 Jul 2021 02:09:10 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id EE06661054; Tue, 27 Jul 2021 06:09:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1627366151; bh=12GRn6/Ruq7Tv7H9GUSviN2q+t9S6N5v5Lcy9EzpXmQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=emP7gDqUhtszgWgqPv4PuPidiHYIboQejjWQj1WwmXBBwvX2vQwilrXcDdq6L4dCP vS+u7HfpvxdnYJ5eANYPI6cxxf4iV3aoRNPm1cGRaDJdBMKJu8cn3i3MMbeR/77yGH MTFdgXW5aqONYf6x3XCDALR0tCf3+FzZ9GaB91n4= Date: Tue, 27 Jul 2021 08:09:09 +0200 From: Greg Kroah-Hartman To: Vasily Averin Cc: Andrew Morton , cgroups@vger.kernel.org, Michal Hocko , Shakeel Butt , Johannes Weiner , Vladimir Davydov , Roman Gushchin , Jiri Slaby , linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 09/10] memcg: enable accounting for tty-related objects Message-ID: References: <6f21a0e0-bd36-b6be-1ffa-0dc86c06c470@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 27, 2021 at 08:34:14AM +0300, Vasily Averin wrote: > At each login the user forces the kernel to create a new terminal and > allocate up to ~1Kb memory for the tty-related structures. > > By default it's allowed to create up to 4096 ptys with 1024 reserve for > initial mount namespace only and the settings are controlled by host admin. > > Though this default is not enough for hosters with thousands > of containers per node. Host admin can be forced to increase it > up to NR_UNIX98_PTY_MAX = 1<<20. > > By default container is restricted by pty mount_opt.max = 1024, > but admin inside container can change it via remount. As a result, > one container can consume almost all allowed ptys > and allocate up to 1Gb of unaccounted memory. > > It is not enough per-se to trigger OOM on host, however anyway, it allows > to significantly exceed the assigned memcg limit and leads to troubles > on the over-committed node. > > It makes sense to account for them to restrict the host's memory > consumption from inside the memcg-limited container. > > Signed-off-by: Vasily Averin > Acked-by: Greg Kroah-Hartman > --- > drivers/tty/tty_io.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) As this is independant of all of the rest, I'll just take this through my tree now so that you do not have to keep resending it. thanks, greg k-h