From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 134963876A5 for ; Thu, 26 Feb 2026 06:43:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772088200; cv=none; b=rC2+70BwdJIBCvXKXpO1reX1lQXF2g5TTBaaUWEosge7NghHUl4GbBia38XKc4cc9EiP25//yCBHR3AF0uG99cTAdV5bkBcSrkSsLl88TGL9j9pU8AAn+K72Dhc9zPm70rH+BKIWKyjqLWURMC8VQPyu+U0AvCZBGcLC4IPQV9g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772088200; c=relaxed/simple; bh=p8R4zmAB9V4nCQaJusrhg0BJhZnx2oFpUwWtRscukWM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MA+tYX0oErRqWWPFl6xfy6WTIn9fqkBtHZf60Dlxmgx2hKt+zLKSPMm+P1lvQBCNqzeNXUGRpa1cDlUwZvCB7xGGRFIVIfxhYXkj353NNObgYOM8OB3s2pDZrrkW4gz78NnK5g3BDluk7/pj+F7Cus32v9E5ll1IINkBLeIiaI0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=HP5Ga7xy; arc=none smtp.client-ip=95.215.58.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="HP5Ga7xy" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1772088196; 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=/gFMs3BNYCLYbp907qyYSrv7ESdIsN4oDF7h/Fu2FJY=; b=HP5Ga7xyX4/Ux+VNCIMWTaLmiC52BjFNZ8ZGo2ljwIaNuUW1j9m0tascLyfYdtnFd+8HtH Z55p50bo9TBs9IZhmfCIXUiw7Tjqv9UwPTuyH3MtGTAf/qgvQ0w8lku/YcCSGDx40MMllu Ogim/cLOLqJMhJFU7U1l3hlNee2bCCo= Date: Thu, 26 Feb 2026 14:42:51 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v5 29/32] mm: memcontrol: prepare for reparenting non-hierarchical stats To: Shakeel Butt , Yosry Ahmed 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, usamaarif642@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Qi Zheng References: 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 On 2/26/26 8:25 AM, Shakeel Butt wrote: > On Wed, Feb 25, 2026 at 06:58:59AM -0800, Yosry Ahmed wrote: >>> @@ -473,6 +493,29 @@ unsigned long lruvec_page_state_local(struct lruvec *lruvec, >>> return x; >>> } >>> >>> +#ifdef CONFIG_MEMCG_V1 >>> +void reparent_memcg_lruvec_state_local(struct mem_cgroup *memcg, >>> + struct mem_cgroup *parent, int idx) >>> +{ >>> + int i = memcg_stats_index(idx); >>> + int nid; >>> + >>> + if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) >>> + return; >>> + >>> + for_each_node(nid) { >>> + struct lruvec *child_lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid)); >>> + struct lruvec *parent_lruvec = mem_cgroup_lruvec(parent, NODE_DATA(nid)); >>> + struct mem_cgroup_per_node *parent_pn; >>> + unsigned long value = lruvec_page_state_local(child_lruvec, idx); >>> + >>> + parent_pn = container_of(parent_lruvec, struct mem_cgroup_per_node, lruvec); >>> + >>> + atomic_long_add(value, &(parent_pn->lruvec_stats->state_local[i])); >>> + } >>> +} >> >> Did you measure the impact of making state_local atomic on the flush >> path? It's a slow path but we've seen pain from it being too slow >> before, because it extends the critical section of the rstat flush >> lock. > > Qi, please measure the impact on flushing and if no impact then no need to do OK, will try to do it. > anything as I don't want anymore churn in this series. Agree. >