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 CA778E9462E for ; Tue, 10 Feb 2026 03:13:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1B5F36B0005; Mon, 9 Feb 2026 22:13:01 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 160926B0088; Mon, 9 Feb 2026 22:13:01 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 062846B0089; Mon, 9 Feb 2026 22:13:00 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id EA7456B0005 for ; Mon, 9 Feb 2026 22:13:00 -0500 (EST) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id A1A99B8915 for ; Tue, 10 Feb 2026 03:13:00 +0000 (UTC) X-FDA: 84427075320.26.D6D995B Received: from out-178.mta1.migadu.com (out-178.mta1.migadu.com [95.215.58.178]) by imf27.hostedemail.com (Postfix) with ESMTP id B5E3240006 for ; Tue, 10 Feb 2026 03:12:58 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Tw7AmvSd; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf27.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.178 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770693179; 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=yubXWpReL8k8hbkA3y11vW86dPL2+7IUWmPBxrke92U=; b=Tr7ly8OqZbS3tYWi9zUoJ6FbVfB8D6kJtYfP8mVxB73cZFH4wBNVXcL4B4k+huXmu7fhWw xFMebYDt8WO7EEgnff87VPAzQR2oO2/PJZkoev6tHwrpxH1vyovAFtk84M8plDA1E+OKo+ YNBOMEQ5VyB3ALKLLCl3t0klzkJVP7o= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770693179; a=rsa-sha256; cv=none; b=UtkiH9ONCpS0F+4F9BOk5xyvsbgWCOJt02+wK7MxPMVpmru9BbTOCNtsOf1Xc9DkDJy/Gw XGLbQjY+a16z4XoyL+DZvU/VW8IiAfXQsZTtnH94RumGpTY84UDztcGU6zbBHKgBaM4/Bj sDDa5rdnP0ExHR93U+DY4ubbwKk9qNQ= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Tw7AmvSd; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf27.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.178 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev Message-ID: <37b79f65-7de3-483a-a675-75eab94d2776@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1770693176; 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=yubXWpReL8k8hbkA3y11vW86dPL2+7IUWmPBxrke92U=; b=Tw7AmvSdFVwfbDs8VZgjXs2x8ddtNiTMeickGrjOWzTBV6Yh/PrtCcJVPvlHTiEQT4idPm PsZ5jlhuAvA8/s0ojPGTXRbI69ELL4rTgSgyXh5Cy+vx4TIoBa4afdD4iaqP/FnrhFCIUY OjMtGYUzjzSSOBP26w82VxQkWD8+BRw= Date: Tue, 10 Feb 2026 11:11:47 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v4 30/31] mm: memcontrol: eliminate the problem of dying memory cgroup for LRU folios To: Shakeel Butt Cc: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, yosry.ahmed@linux.dev, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev, bhe@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng References: <9e332cc8436b6092dd6ef9c2d5f69072bb38eaf6.1770279888.git.zhengqi.arch@bytedance.com> <2a0e4ae2-457b-4d16-a7b9-7372fd665337@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: B5E3240006 X-Stat-Signature: pxfguoh47hksxb3g176mqpijh1aak7bo X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1770693178-984998 X-HE-Meta: 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 Ykli/2Rb nIBlUbWVD9ruHP/2zkKx+z20YcK5h+/dUshmwoSYzpIAAJkHEMkNA2IDkyQK56jS/hq5nebMa86Mn3q+ztz/BaUR27L7ieYuO8X1SCmB5nqs2hUPDQ2DK5e8UV5YcOX5HX8XifnboIZQYPt6vOYs1EunfS0j8UmI+UiNmrplvZ1qMX3ua5VbrgMsR4fSodR+FQSsmeILwH4D1H2c68kq8+iz/ZyR/EoRN5l34aU+biDzIR85/ijGLEhEqj2fk8zTYSklkw8/CWMtrUmY= 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 2/10/26 1:53 AM, Shakeel Butt wrote: > On Mon, Feb 09, 2026 at 11:49:43AM +0800, Qi Zheng wrote: >> >> >> On 2/8/26 6:25 AM, Shakeel Butt wrote: >>> On Thu, Feb 05, 2026 at 05:01:49PM +0800, Qi Zheng wrote: >>>> From: Muchun Song >>>> >>>> Now that everything is set up, switch folio->memcg_data pointers to >>>> objcgs, update the accessors, and execute reparenting on cgroup death. >>>> >>>> Finally, folio->memcg_data of LRU folios and kmem folios will always >>>> point to an object cgroup pointer. The folio->memcg_data of slab >>>> folios will point to an vector of object cgroups. >>>> >>>> Signed-off-by: Muchun Song >>>> Signed-off-by: Qi Zheng >>>> /* >>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>>> index e7d4e4ff411b6..0e0efaa511d3d 100644 >>>> --- a/mm/memcontrol.c >>>> +++ b/mm/memcontrol.c >>>> @@ -247,11 +247,25 @@ static inline void reparent_state_local(struct mem_cgroup *memcg, struct mem_cgr >>>> static inline void reparent_locks(struct mem_cgroup *memcg, struct mem_cgroup *parent) >>>> { >>>> + int nid, nest = 0; >>>> + >>>> spin_lock_irq(&objcg_lock); >>>> + for_each_node(nid) { >>>> + spin_lock_nested(&mem_cgroup_lruvec(memcg, >>>> + NODE_DATA(nid))->lru_lock, nest++); >>>> + spin_lock_nested(&mem_cgroup_lruvec(parent, >>>> + NODE_DATA(nid))->lru_lock, nest++); >>> >>> Is there a reason to acquire locks for all the node together? Why not do >>> the for_each_node(nid) in memcg_reparent_objcgs() and then reparent the >>> LRUs for each node one by one and taking and releasing lock >>> individually. Though the lock for the offlining memcg might not be >> >> To do this, we first need to convert objcg from per-memcg to per-memcg >> per-node. In this way, we can hold the lru lock and objcg lock for >> each node to reparent the folio and the corresponding objcg together. > > Oh we want reparenting of both objcg and folio atomic. Let's add a Right. > comment here with the explanation. OK, will do this refactoring and send v5. Thanks, Qi >