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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21112C433F5 for ; Fri, 1 Apr 2022 21:14:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352741AbiDAVQq (ORCPT ); Fri, 1 Apr 2022 17:16:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245368AbiDAVQp (ORCPT ); Fri, 1 Apr 2022 17:16:45 -0400 Received: from out2.migadu.com (out2.migadu.com [IPv6:2001:41d0:2:aacc::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87D667A98C for ; Fri, 1 Apr 2022 14:14:55 -0700 (PDT) Date: Fri, 1 Apr 2022 14:14:44 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1648847690; 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=qQPbMxATgPsqR0bbHUcTP6NBEErFcNaDM6bna/D7CWc=; b=S1xB/VeBA2PtdLMYm1TIUy3l5XknOdb7JYkFyCUActTxWOhIhfbV19hvwDT62ns5ZeIN64 tk4jS6o4OHLGg8jKou/3GF7wwWigcrw4ZsMyVGulwhw/mHUOHnoNyhfn+t90jS/ypz76ur Q0PlSXXlJKqdj9aZJT8JGRhk7/8+nL0= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Roman Gushchin To: Florian Westphal Cc: Vasily Averin , Pablo Neira Ayuso , kernel@openvz.org, Jozsef Kadlecsik , netfilter-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH nft] nft: memcg accounting for dynamically allocated objects Message-ID: References: <20220401120342.GC9545@breakpoint.cc> <7bfa2e2e-b22d-7561-661b-41ef7714caf5@linux.dev> <20220401193159.GB28321@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220401193159.GB28321@breakpoint.cc> X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Fri, Apr 01, 2022 at 09:31:59PM +0200, Florian Westphal wrote: > Vasily Averin wrote: > > > Same problem as connlimit, can be called from packet path. > > > Basically all GFP_ATOMIC are suspicious. > > > > > > Not sure how to resolve this, similar mechanics in iptables world (e.g. > > > connlimit or SET target) don't use memcg accounting. > > > > > > Perhaps for now resend with only the GFP_KERNEL parts converted? > > > Those are safe. > > > > It is safe for packet path too, _ACCOUNT allocation will not be able to find memcg > > in case of "!in_task()" context. > > On the other hand any additional checks on such path will affect performance. > > I'm not sure this works with ksoftirqd serving network stack? > > > Could you please estimate how often is this code used in the case of nft vs packet path? > > It depends on user configuration. > Update from packet path is used for things like port knocking or other > dyanamic filter lists, or somehing like Limiting connections to x-per-address/subnet and so on. > > > If the opposite is the case, then I can add __GFP_ACCOUNT flag depending on in_task() check. > > But what task/memcg is used for the accounting in that case? Root memcg/no accounting, which is the same. There is a way to account for a specific memcg in such cases, it's used for bpf maps, for example. We save a pointer to the memcg which created the map and charge it for all allocations from a !in_task context. But the performance can be affected, so let's not do without regression tests and a serious need. Thanks!