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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D4B1C43334 for ; Tue, 12 Jul 2022 09:52:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 85C826B00E6; Tue, 12 Jul 2022 05:52:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7BD116B00EA; Tue, 12 Jul 2022 05:52:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 65C6A6B00EC; Tue, 12 Jul 2022 05:52:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 5245F6B00E6 for ; Tue, 12 Jul 2022 05:52:16 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 1D07D33B86 for ; Tue, 12 Jul 2022 09:52:16 +0000 (UTC) X-FDA: 79677982272.08.7FC0778 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf12.hostedemail.com (Postfix) with ESMTP id 915EB4006A for ; Tue, 12 Jul 2022 09:52:15 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 375761F96B; Tue, 12 Jul 2022 09:52:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1657619534; h=from:from:reply-to: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=pm4VPHZ7hwTErGyoQgCSf/HU8qiZ3Mug86BUwr6Vsew=; b=Mh1Wn8yFVQcQ5nJ4E8dYkxnDW/OGEJV0bjE14MV8rW2DkKs5Dha8eWapckuaPZwK+scDOk fzguBpWnXmFXX8bv+X7th5QqVZuZ300e3+CDugbhBDuw6PPxqdFB4CPmpp1Qx2Inroht0T NWJOeGay1zVpHKaekvL3B3CrAkEtLUw= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id F351C2C141; Tue, 12 Jul 2022 09:52:11 +0000 (UTC) Date: Tue, 12 Jul 2022 11:52:11 +0200 From: Michal Hocko To: Yafang Shao Cc: Alexei Starovoitov , Shakeel Butt , Matthew Wilcox , Christoph Hellwig , "David S. Miller" , Daniel Borkmann , Andrii Nakryiko , Tejun Heo , Martin KaFai Lau , bpf , Kernel Team , linux-mm , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka Subject: Re: [PATCH bpf-next 0/5] bpf: BPF specific memory allocator. Message-ID: References: <20220706180525.ozkxnbifgd4vzxym@MacBook-Pro-3.local.dhcp.thefacebook.com> <20220708174858.6gl2ag3asmoimpoe@macbook-pro-3.dhcp.thefacebook.com> <20220708215536.pqclxdqvtrfll2y4@google.com> <20220710073213.bkkdweiqrlnr35sv@google.com> <20220712043914.pxmbm7vockuvpmmh@macbook-pro-3.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=Mh1Wn8yF; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf12.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657619535; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=pm4VPHZ7hwTErGyoQgCSf/HU8qiZ3Mug86BUwr6Vsew=; b=kUzZ8XNAffwMlUPZUpNMQjK5PSEpDvwr6Ls0nw+T2qz2p1LGRWpgH6nLkEN3rkkgBVtP8L jJt/1SiBYuVhiQaP8uHhe9XmuRzQMddlUGFIx5NMi6vy5xJuEsnOMjGgsHHUM+1IitfG6T 3U8XYFNwekHJIQLEof7HBNvbf+DOE3I= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657619535; a=rsa-sha256; cv=none; b=qdrYydWTtNo4cIaWuwx9sNQJ3S1Vl4xdf+3r0UYhlLfr7Y47HWsLn7ccPeFj6+7Lz4eIPj X9XTDdk2WW/Vn+K+Fg/NmEglR2HPssue8k0OXufVacbYIQoD9ZnrEe9t9l8hR2Zw3Ajb2Z tcgCnYXbxphpWf8hG7RzHE1jysdW380= Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=Mh1Wn8yF; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf12.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com X-Rspam-User: X-Rspamd-Server: rspam08 X-Stat-Signature: epb7imq5q9qqhpfqfjunq5wyyw3wm7u7 X-Rspamd-Queue-Id: 915EB4006A X-HE-Tag: 1657619535-706443 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 12-07-22 16:39:48, Yafang Shao wrote: > On Tue, Jul 12, 2022 at 3:40 PM Michal Hocko wrote: [...] > > > Roman already sent reparenting fix: > > > https://patchwork.kernel.org/project/netdevbpf/patch/20220711162827.184743-1-roman.gushchin@linux.dev/ > > > > Reparenting is nice but not a silver bullet. Consider a shallow > > hierarchy where the charging happens in the first level under the root > > memcg. Reparenting to the root is just pushing everything under the > > system resources category. > > > > Agreed. That's why I don't like reparenting. > Reparenting just reparent the charged pages and then redirect the new > charge, but can't reparents the 'limit' of the original memcg. > So it is a risk if the original memcg is still being charged. We have > to forbid the destruction of the original memcg. yes, I was toying with an idea like that. I guess we really want a measure to keep cgroups around if they are bound to a resource which is sticky itself. I am not sure how many other resources like BPF (aka module like) we already do charge for memcg but considering the potential memory consumption just reparenting will not help in general case I am afraid. -- Michal Hocko SUSE Labs