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=-15.9 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 6752BC432BE for ; Tue, 27 Jul 2021 06:54:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43177610D1 for ; Tue, 27 Jul 2021 06:54:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235657AbhG0Gyi (ORCPT ); Tue, 27 Jul 2021 02:54:38 -0400 Received: from mail-wm1-f53.google.com ([209.85.128.53]:43573 "EHLO mail-wm1-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234349AbhG0Gyd (ORCPT ); Tue, 27 Jul 2021 02:54:33 -0400 Received: by mail-wm1-f53.google.com with SMTP id m20-20020a05600c4f54b029024e75a15716so1568909wmq.2; Mon, 26 Jul 2021 23:54:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=aaW7cFw+oCFWM/dmmy7Fk93SXTQV0wxby9I/PRxiL4c=; b=mm+Lxm8cVSQOnilaLWWRArZ4654l0xlZSyBHgyDaMhy0+F43HIuhyue/KPMcnTIvEc E/VNDDCiMtJDEga4sSgz9XJTBf2MUxoC7+CWF6drYIxhVEBw4k2aK+kX7Ft9+VPFGFxG SyvobGT3hAHjaMHAZwyl3DGoIdQARN8JTyu5e+ro0i6Enqs02PUt2oAVafRQs/MU087f RZ+Q25ujjKKAVbWUdkzwEYLFI4rXfkNHRSsEuph9gJpW0ELyb40ZHNVHOEdN/HkCYjbk SaifLrPsUCqWILB7y1nLjFyfue5dBK05HZG9P5clWY2rsiYypuLQaE1TcQ6syT8WjsfM lBFg== X-Gm-Message-State: AOAM532JtP36Q+YCBHWFkxBOBt2ZL/RIN6bPO3MWlRGEw0PP0kxNAXTe tkQ/GSGU8F4418Fnfd1hUOiu6cSfFXW5Yw== X-Google-Smtp-Source: ABdhPJxIWCHbsXVIVvCyRBAf9hyz35xq2EdGm1WfHnZDkv4s9+x7rYlA1/oYB3fZBZCaca8Y+ES5vA== X-Received: by 2002:a7b:ce08:: with SMTP id m8mr2518480wmc.21.1627368872670; Mon, 26 Jul 2021 23:54:32 -0700 (PDT) Received: from ?IPv6:2a0b:e7c0:0:107::70f? ([2a0b:e7c0:0:107::70f]) by smtp.gmail.com with ESMTPSA id v15sm1738843wmj.39.2021.07.26.23.54.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Jul 2021 23:54:31 -0700 (PDT) Subject: Re: [PATCH v7 09/10] memcg: enable accounting for tty-related objects To: Vasily Averin , Andrew Morton Cc: cgroups@vger.kernel.org, Michal Hocko , Shakeel Butt , Johannes Weiner , Vladimir Davydov , Roman Gushchin , Greg Kroah-Hartman , linux-kernel@vger.kernel.org References: <6f21a0e0-bd36-b6be-1ffa-0dc86c06c470@virtuozzo.com> From: Jiri Slaby Message-ID: <1eef95fe-6172-796e-edd1-095545da6e74@kernel.org> Date: Tue, 27 Jul 2021 08:54:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27. 07. 21, 7:34, 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(-) > > diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c > index 26debec..e787f6f 100644 > --- a/drivers/tty/tty_io.c > +++ b/drivers/tty/tty_io.c > @@ -1493,7 +1493,7 @@ void tty_save_termios(struct tty_struct *tty) > /* Stash the termios data */ > tp = tty->driver->termios[idx]; > if (tp == NULL) { > - tp = kmalloc(sizeof(*tp), GFP_KERNEL); > + tp = kmalloc(sizeof(*tp), GFP_KERNEL_ACCOUNT); termios are not saved for PTYs (TTY_DRIVER_RESET_TERMIOS). Am I missing something? > if (tp == NULL) > return; > tty->driver->termios[idx] = tp; > @@ -3119,7 +3119,7 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx) > { > struct tty_struct *tty; > > - tty = kzalloc(sizeof(*tty), GFP_KERNEL); > + tty = kzalloc(sizeof(*tty), GFP_KERNEL_ACCOUNT); > if (!tty) > return NULL; > > thanks, -- js suse labs