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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4BC59CAC5BA for ; Thu, 25 Sep 2025 19:35:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9A5568E0002; Thu, 25 Sep 2025 15:35:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 97DA38E0001; Thu, 25 Sep 2025 15:35:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86C218E0002; Thu, 25 Sep 2025 15:35:13 -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 771398E0001 for ; Thu, 25 Sep 2025 15:35:13 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 1143F1A04C1 for ; Thu, 25 Sep 2025 19:35:13 +0000 (UTC) X-FDA: 83928776106.09.6C05727 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf12.hostedemail.com (Postfix) with ESMTP id E54E040006 for ; Thu, 25 Sep 2025 19:35:10 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=V0OA8pQs; spf=pass (imf12.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1758828911; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=VJwwywmn8MlVeferLmRGbOLpNjhdj0h30dn2f1aSujg=; b=YxwdsY1GpGncxwCDXwiNOMeKhT1ZZ+TUpBGApxLCdhTDmThhR1LmrtnJI+1fggGx7DiNpz X+k+YIGy7f7ijiuGzBBgveIl+bw1+VoQnW7J/EEJYVpP/6M0X3kVfcBC50orECp314B5lq WH+DNYSFZd3//FymTu33MFBv2MyIBbw= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1758828911; a=rsa-sha256; cv=none; b=ZnuwGXMKD0R2RHT/nN2VeueooVzUyBg6EaB7+wsgu9wuLa/T4b6eosXJHmm9qsFfhpxDzj j97gj4DhiUD04SI/fvdFXbXGHIQPdzkm6ATNvKmpX5kWrQz5rvDNMZ1/i1R49i0kQhqNDS EgYPm5kaDcR2+lGE0aj8Fofuxe4qp0Q= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=V0OA8pQs; spf=pass (imf12.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758828910; 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:autocrypt:autocrypt; bh=VJwwywmn8MlVeferLmRGbOLpNjhdj0h30dn2f1aSujg=; b=V0OA8pQsRJu2iwwv3QXtn5Xj4KNfVUWs1zLoEncvcEPaj1Z2xjMGlLn80CwGe6eeayKHBS yOGUyoyqxPpG6MoWd4TW5FzUbGzwJ0RYM/8JAVtnQlbx8tA/V6HvhOHveKLn8tl7yXZWsi ZILcwXfTVMdCfs8OErYzK+vuRPm1yws= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-98-9xTRVrPePCWoh2GH5LQpFQ-1; Thu, 25 Sep 2025 15:35:06 -0400 X-MC-Unique: 9xTRVrPePCWoh2GH5LQpFQ-1 X-Mimecast-MFC-AGG-ID: 9xTRVrPePCWoh2GH5LQpFQ_1758828905 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-46e25f5ed85so8676715e9.3 for ; Thu, 25 Sep 2025 12:35:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758828905; x=1759433705; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=VJwwywmn8MlVeferLmRGbOLpNjhdj0h30dn2f1aSujg=; b=Ic+Fn5dpnVBS+gKvwR/cqSvo/VrH6vj2/UUdM28Zq5dAfydTwvMIUnVrvDOY2SSXfW 8i4ZvDqMsZbyEotK/HIbj8m26bu6oyQ0ie7XJcVxzYqovFvAm+GHcX0S7EpVcgER8WAb 1HQSUpKFMA0RY6+vFcBKjRwMecSlKxlwN9u2kOqzr+iy5qHyTaNuceRfSnAkj9wqE5Tl djPtOOH0/7H6QhCc/G7gzT6881X2xbJU+GNOSwHWqhtJcGETz2K8mISnw0mQBYSRTVeM PUQnosjhlvCDSLnV2I7MZZtJeka3LfM/+sSNOiVpqLqlRbRRKBEqpn2lrKu7bJb/204/ SA9w== X-Gm-Message-State: AOJu0YwqyaW7lkcjQVCOkBItj4mHzJGhP2TwDPeH5j9ID9zuK8V4M6eD WSqZ36OmqphioXoT9Q8Ph8GORkKUvowa5EKqCLehllua4zC2dTNG/b3jdXwCtx4qLCUUlhYtGNM p9hX+QM/bP3p70DJzapvl5riB54t73kJoOBBOcmGk1l24eq6+9/bB X-Gm-Gg: ASbGnctnForiegNgakDxMNAL6am5TItJWGNok4tq6S0U6R+Pl1+HxiUBejRkXqXhbfJ 1iMSmsgP1zZUL7J5jCHiNVXYR+GWt/veEZpNkdVF02yCmPVIYNu+eiKWo2nMmFZbEhWH/diMG6S y3pYpsYCdjHeaeSqZBhHQCax4xl8tI+t835irO0wFB1mZemRrnGt7VkUAPGMovKTD3EzzwE+l6C IqmKk78kwoE51uusfo92FsMNr/82CEy1EkAmr+A924DPlmrtIxunQ7zOmng/zErn7+4D4N0byTa CVoN9WZ4zZiOsoLphG2vo0h+rqf8ORHiLCVCeYn76MhZkGGvVFPmnqIp182Nr7nEWGq0KdDoxb8 kLSSqFFS7luho/epmFv7I7//m0m9PM9gcZR5tlJ3G5PkNNhw02yVH5zLGicoHVOJxvTDH X-Received: by 2002:a05:600c:c04b:10b0:46e:2d0d:8053 with SMTP id 5b1f17b1804b1-46e32a30481mr40382395e9.18.1758828904935; Thu, 25 Sep 2025 12:35:04 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGd82MPk0+1Hmip3UQRbBk+SH7Cq3z6WmT4cbaRtBd04WMOf1YdLsAcp6Q0b+Vu83a2w7bdQg== X-Received: by 2002:a05:600c:c04b:10b0:46e:2d0d:8053 with SMTP id 5b1f17b1804b1-46e32a30481mr40382185e9.18.1758828904542; Thu, 25 Sep 2025 12:35:04 -0700 (PDT) Received: from ?IPV6:2003:d8:2f3f:f800:c101:5c9f:3bc9:3d08? (p200300d82f3ff800c1015c9f3bc93d08.dip0.t-ipconnect.de. [2003:d8:2f3f:f800:c101:5c9f:3bc9:3d08]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46e2a9b6e1bsm99082945e9.10.2025.09.25.12.35.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Sep 2025 12:35:04 -0700 (PDT) Message-ID: <39f22c1a-705e-4e76-919a-2ca99d1ed7d6@redhat.com> Date: Thu, 25 Sep 2025 21:35:02 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/4] mm: thp: reparent the split queue during memcg offline To: Qi Zheng , hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org References: <55370bda7b2df617033ac12116c1712144bb7591.1758618527.git.zhengqi.arch@bytedance.com> <46da5d33-20d5-4b32-bca5-466474424178@bytedance.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <46da5d33-20d5-4b32-bca5-466474424178@bytedance.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: ZULXtur0MlWqKB-ngo3NHT-TZ4BvGbwH3XJIgbCsKNc_1758828905 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: 3eyt9zsoqzzmgpecw4toghfmd13eyxp6 X-Rspam-User: X-Rspamd-Queue-Id: E54E040006 X-Rspamd-Server: rspam10 X-HE-Tag: 1758828910-847133 X-HE-Meta: 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 Yg24+auh 6dzYeBjZnAU4GPTVBCQ6oH+kNagIEUFwAnVQUNroUcm3+xp4= 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: List-Subscribe: List-Unsubscribe: On 25.09.25 08:11, Qi Zheng wrote: > Hi David, Hi :) [...] >>> +++ b/include/linux/mmzone.h >>> @@ -1346,6 +1346,7 @@ struct deferred_split { >>>       spinlock_t split_queue_lock; >>>       struct list_head split_queue; >>>       unsigned long split_queue_len; >>> +    bool is_dying; >> >> It's a bit weird to query whether the "struct deferred_split" is dying. >> Shouldn't this be a memcg property? (and in particular, not exist for > > There is indeed a CSS_DYING flag. But we must modify 'is_dying' under > the protection of the split_queue_lock, otherwise the folio may be added > back to the deferred_split of child memcg. Is there no way to reuse the existing mechanisms, and find a way to have the shrinker / queue locking sync against that? There is also the offline_css() function where we clear CSS_ONLINE. But it happens after calling ss->css_offline(css); Being able to query "is the memcg going offline" and having a way to sync against that would be probably cleanest. I'll let all the memcg people comment on how that could be done best. > >> the pglist_data part where it might not make sense at all?). > > Maybe: > > #ifdef CONFIG_MEMCG > bool is_dying; > #endif > Still doesn't quite look like it would belong here :( Also, is "dying" really the right terminology? It's more like "going offline"? But then, the queue is not going offline, the memcg is ... -- Cheers David / dhildenb