From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-151.mta0.migadu.com [91.218.175.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 36BFE4B8DE8 for ; Thu, 3 Sep 2026 17:56:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.151 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788458189; cv=none; b=pWIifwrLzrPXuR3fFHSyvq0xJQJ1OKmc+VP0YFBsWUgnJrpVdR9Q+8THcZ8/URAjU4A2ekJ61+DLB810uWtmW+cd9tqR/fvlpLJdd9FkJOFwW9b0IvQ3x0H0mDVf1IqzI89J+w3HXVWh4c4ekpyIvW+WsPXMWBx/GNN7JgrSj6E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788458189; c=relaxed/simple; bh=L3+7YRmfESLibVZakMPl0uWAeXL3XzaW/tLxNhJw+VI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kPas3wgB0W8diaLUUS2RCMLqljw3JTNMK7qtFr7Vo6kEzg+hqW9p0cA/mQKmwnIPPvg0ejiTxRMUz9yGh5g0160SCj0wph8yaPE/bUxkf3bRFus9pHmYFb6XN8W5MeCEBBcyHc/hBfqRcc6lIAkIAGYtiitQYWmucbZ3H5PaxzM= 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=GkqDu/f/; arc=none smtp.client-ip=91.218.175.151 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="GkqDu/f/" X-Envelope-To: cgroups@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=L3+7YRmfESLibVZakMPl0uWAeXL3XzaW/tLxNhJw+VI=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788458183; v=1; x=1789062983; b=GkqDu/f/acM8xjZ2oIqmjySdRKIgfYfzIbyQbI1tITB467RZ9GR9SDBOkcOjuTsW2gHWGL7t oAMyv/EPMr6u+9upWNjo6UdE3cX/M7xkOjAQ0kUCdEIeTGEPNfkfi6TacgOPlOfmM/5DFUs1Zid 4JLRgvZceBtK9ZzHFZR2Etag= X-Envelope-To: cgroups@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id a4bed8d3f0db8ac7; Thu, 03 Sep 2026 17:56:23 +0000 X-Mizu-Trace-ID: a4bed8d3f0db8ac7 X-Migadu-Flow: FLOW_OUT Date: Thu, 3 Sep 2026 10:56:22 -0700 From: Shakeel Butt To: Hui Zhu Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Andrew Morton , David Hildenbrand , Qi Zheng , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hui Zhu Subject: Re: [PATCH v2 2/3] mm: memcg: redirect stats updates of dying memcgs for all hierarchies Message-ID: References: <0214c0228695db474b86d3b4778b681a6c47a6e2.1788169145.git.zhuhui@kylinos.cn> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0214c0228695db474b86d3b4778b681a6c47a6e2.1788169145.git.zhuhui@kylinos.cn> On Mon, Aug 31, 2026 at 05:46:10PM +0800, Hui Zhu wrote: > From: Hui Zhu > > get_non_dying_memcg_start() redirects the stat updates of a dying memcg to > its closest non-dying ancestor, but only on cgroup v1; on cgroup v2 the > stats keep being accounted to the dying memcg itself. > > The previous patch restored lruvec_page_state_local() in > count_shadow_nodes(), which reads those state_locals on cgroup v2 too, so > apply the redirection to all hierarchies. Offlining is rare, so the added > cost on the stat update fast path is limited to an rcu_read_lock() and a > css_is_dying() check; the upward walk happens only while a memcg is dying. > > Signed-off-by: Hui Zhu Please CC to stable and add a sentence on user visible impact of the bug in the commit message. With that: Acked-by: Shakeel Butt