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 1336BC433FE for ; Mon, 31 Jan 2022 17:15:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245379AbiAaRPp (ORCPT ); Mon, 31 Jan 2022 12:15:45 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:50666 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380795AbiAaRP2 (ORCPT ); Mon, 31 Jan 2022 12:15:28 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643649328; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=517osVusanMuP0Y4/rkshkWytofYaoASsE2dV7IDjz4=; b=GQoIFbBRWeiRf4N9CsF7PdyA0eHlVE0YH4YINazUsLg4a7bkjpLgZF3NFAMlskNnqT162r E2eoG6s0dx7uYIBUn1CIgvlylD2reMkd7hvr8CyfbQEBfN56xPixSd5sXU1Y4sWiWycTKm HOozRL7UumCIGKepaPq4mst2yEZa4Eg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-473-ccm5_wRKMk-Plwz2607tUA-1; Mon, 31 Jan 2022 12:15:24 -0500 X-MC-Unique: ccm5_wRKMk-Plwz2607tUA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A21701006AA3; Mon, 31 Jan 2022 17:15:21 +0000 (UTC) Received: from [10.22.16.244] (unknown [10.22.16.244]) by smtp.corp.redhat.com (Postfix) with ESMTP id 483A77744B; Mon, 31 Jan 2022 17:15:20 +0000 (UTC) Message-ID: Date: Mon, 31 Jan 2022 12:15:19 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH 1/3] mm, memcg: Don't put offlined memcg into local stock Content-Language: en-US From: Waiman Long To: Roman Gushchin Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Vlastimil Babka , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Shakeel Butt , Muchun Song References: <20211001190938.14050-1-longman@redhat.com> <20211001190938.14050-2-longman@redhat.com> <95ba1931-e9c9-45c3-b080-d28f2ad368a7@redhat.com> In-Reply-To: <95ba1931-e9c9-45c3-b080-d28f2ad368a7@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/31/22 12:09, Waiman Long wrote: > On 1/31/22 12:01, Roman Gushchin wrote: >> On Sun, Jan 30, 2022 at 10:55:56PM -0500, Waiman Long wrote: >>> On 10/1/21 19:51, Roman Gushchin wrote: >>>> On Fri, Oct 01, 2021 at 03:09:36PM -0400, Waiman Long wrote: >>>>> When freeing a page associated with an offlined memcg, refill_stock() >>>>> will put it into local stock delaying its demise until another memcg >>>>> comes in to take its place in the stock. To avoid that, we now check >>>>> for offlined memcg and go directly in this case to the slowpath for >>>>> the uncharge via the repurposed cancel_charge() function. >>>> Hi Waiman! >>>> >>>> I'm afraid it can make a cleanup of a dying cgroup slower: for every >>>> released page we'll potentially traverse the whole cgroup tree and >>>> decrease atomic page counters. >>>> >>>> I'm not sure I understand the benefits we get from this change which >>>> do justify the slowdown on the cleanup path. >>>> >>>> Thanks! >>> I was notified of a lockdep splat that this patch may help to prevent. >> Would you mind to test this patch: >> https://www.spinics.net/lists/cgroups/msg31244.html ? >> >> It should address this dependency. > > Thanks for the pointer. I believe that your patch should be able to > address this circular locking dependency. > > Feel free to add my > > Reviewed-by: Waiman Long BTW, have you posted it to lkml? If not, would you mind doing so? Thanks, Longman