From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-108.mta1.migadu.com [95.215.58.108]) (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 4B570492187 for ; Wed, 12 Aug 2026 23:44:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786578268; cv=none; b=exJB2I/TkkVdtSOZfydPAgCReLFhqVkeGGq6kYQNzuubM0tyaaGJtfuClsSFDUNBYIGESqzsU09VRzzZD5QO3Q6Ym/IDyn1VQz3inh+ndlZV/OaUaDhWY3cFSlFPgWDkWGXwha8YJv5Oo43ZGOgbkIFfC0FP1lbp5py3u5+67I8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786578268; c=relaxed/simple; bh=GRGPu0x1sRERIuQs56PTW8nQYd9NgZlk3OlXceQWbKE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=T8XN3+SKO0VLR/vQo2Cx55eKD/0jjvjh5RsjrYcz5f3udHrTMyatEoXbXhBi/czQ2eqPZEWyxutPK4NvZSq4nmpUvBVWnHEhVqiVOAFIYkpQB7rg64uOkxTEeA5ZhyCvr07GHkRR1jOKNCBVmFmiEFo9ORVLJL0exTvoo8ac8lM= 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=V7Au1q1M; arc=none smtp.client-ip=95.215.58.108 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="V7Au1q1M" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=GRGPu0x1sRERIuQs56PTW8nQYd9NgZlk3OlXceQWbKE=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786578265; v=1; x=1787183065; b=V7Au1q1M522y8KIDAXqAu3KtyfWzd2A2IYxgxXkZPwVPEnBlOOFlRiy2BRPHLE6WeS/cJkgO smiZye2sltUNYM69JXanNC58hwcca1b+HXG21ihDSu5ecs5SRDDJf8S76gg919S5ej7BlVE+wHK jfKBlhCtrZcR9868IexsKYZU= X-Envelope-To: linux-kernel@vger.kernel.org Received: from localhost (2a03:2880:10ff::) by smtp.migadu.com with ESMTPS id d0345f5f1396112a; Wed, 12 Aug 2026 23:44:25 +0000 X-Migadu-Flow: FLOW_OUT Date: Wed, 12 Aug 2026 16:44:19 -0700 From: Shakeel Butt To: Guopeng Zhang Cc: Johannes Weiner , Roman Gushchin , Vlastimil Babka , Andrew Morton , Michal Hocko , Muchun Song , Harry Yoo , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Guopeng Zhang , Ran Xiaokai Subject: Re: [PATCH] mm: memcg: fix slab over-accounting for in-object objcg metadata Message-ID: References: <20260812124858.73487-1-guopeng.zhang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260812124858.73487-1-guopeng.zhang@linux.dev> On Wed, Aug 12, 2026 at 08:48:58PM +0800, Guopeng Zhang wrote: > From: Guopeng Zhang > > obj_full_size() adds the size of an obj_cgroup pointer to s->size to > account for slabobj_ext storage, which normally resides outside the > object. > > Since commit a77d6d338685 ("mm/slab: place slabobj_ext metadata in > unused space within s->size"), slabobj_ext can reside in object padding > already covered by s->size. The extra charge then accounts for the same > memory twice. > > The per-slab obj_exts_in_object bit introduced by commit b5bc35ace2c5 > ("mm/slab: replace slab.stride with obj_exts_in_object") identifies this > layout. Use it to omit the extra charge only for in-object metadata. > Unlike in-object metadata, slab-leftover and separately allocated metadata > are not covered by the per-object s->size charge, so retain the existing > charge for those cases. > > Reported-by: Ran Xiaokai > Link: https://lore.kernel.org/all/20260310113804.245647-1-ranxiaokai627@163.com/ > Fixes: a77d6d338685 ("mm/slab: place slabobj_ext metadata in unused space within s->size") > Signed-off-by: Guopeng Zhang This looks good to me but would love to have Harry's comment on it.