From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752917AbeDJMTH (ORCPT ); Tue, 10 Apr 2018 08:19:07 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:46434 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752892AbeDJMTF (ORCPT ); Tue, 10 Apr 2018 08:19:05 -0400 Date: Tue, 10 Apr 2018 05:19:04 -0700 From: Matthew Wilcox To: =?utf-8?B?0JTQvNC40YLRgNC40Lkg0JvQtdC+0L3RgtGM0LXQsg==?= Cc: Michal Hocko , LKML , linux-mm@kvack.org, Vlastimil Babka Subject: Re: __GFP_LOW Message-ID: <20180410121904.GD22118@bombadil.infradead.org> References: <20180405153240.GO6312@dhcp22.suse.cz> <20180405161501.GD28128@bombadil.infradead.org> <20180405185444.GQ6312@dhcp22.suse.cz> <20180405201557.GA3666@bombadil.infradead.org> <20180406060953.GA8286@dhcp22.suse.cz> <20180408042709.GC32632@bombadil.infradead.org> <20180409073407.GD21835@dhcp22.suse.cz> <20180409155157.GC11756@bombadil.infradead.org> <20180409181400.GO21835@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 10, 2018 at 03:12:37PM +0300, Дмитрий Леонтьев wrote: > First, I've noticed the network drivers were allocating memory in interrupt > handlers. That sounds strange to me, because as far as I know, this > behaviour is discouraged and may lead to DDOS attack. Linux supports allocating memory in interrupt context. We also support allocating memory while holding locks. Doing it any other way would require the network stack to preallocate all of the memory it's going to use. You can pop over to the netdev mailing list and ask them to stop this behaviour, but I don't think they'll be very sympathetic. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 620576B0022 for ; Tue, 10 Apr 2018 08:19:07 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id z20so70881pfn.11 for ; Tue, 10 Apr 2018 05:19:07 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2607:7c80:54:e::133]) by mx.google.com with ESMTPS id 1-v6si2589212plj.275.2018.04.10.05.19.06 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 10 Apr 2018 05:19:06 -0700 (PDT) Date: Tue, 10 Apr 2018 05:19:04 -0700 From: Matthew Wilcox Subject: Re: __GFP_LOW Message-ID: <20180410121904.GD22118@bombadil.infradead.org> References: <20180405153240.GO6312@dhcp22.suse.cz> <20180405161501.GD28128@bombadil.infradead.org> <20180405185444.GQ6312@dhcp22.suse.cz> <20180405201557.GA3666@bombadil.infradead.org> <20180406060953.GA8286@dhcp22.suse.cz> <20180408042709.GC32632@bombadil.infradead.org> <20180409073407.GD21835@dhcp22.suse.cz> <20180409155157.GC11756@bombadil.infradead.org> <20180409181400.GO21835@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: =?utf-8?B?0JTQvNC40YLRgNC40Lkg0JvQtdC+0L3RgtGM0LXQsg==?= Cc: Michal Hocko , LKML , linux-mm@kvack.org, Vlastimil Babka On Tue, Apr 10, 2018 at 03:12:37PM +0300, D?D 1/4 D,N?N?D,D1 D?DuD 3/4 D 1/2 N?N?DuD2 wrote: > First, I've noticed the network drivers were allocating memory in interrupt > handlers. That sounds strange to me, because as far as I know, this > behaviour is discouraged and may lead to DDOS attack. Linux supports allocating memory in interrupt context. We also support allocating memory while holding locks. Doing it any other way would require the network stack to preallocate all of the memory it's going to use. You can pop over to the netdev mailing list and ask them to stop this behaviour, but I don't think they'll be very sympathetic.