From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-186.mta0.migadu.com (out-186.mta0.migadu.com [91.218.175.186]) (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 1D32B3659FB for ; Tue, 26 May 2026 03:40:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.186 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779766802; cv=none; b=YDVta9mJvwtlxqTl8vZ+rkAgL8zhCM2nIa3fiijseDEMegxjR63JyDyxiq0j5/JzhIpFeBcqGnvhyrhRhY+/kFMXwtAgySS2deOBxJnxAcLId/Yy61A4Q1XTXdJMzGL3hJb/izudRmXAPermCfU6dPGrg8vY9ilA057Y1pT51ew= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779766802; c=relaxed/simple; bh=vEkRq3gc4x7XgLRH1/Exa1P6r4/ooj7Ohe9F4HT/gRQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=q0IAGH3a1HSIeGxBxM25r0TBAojtMAne76R/jOKlK2glNPilic+mjHf3XUPREJg0ckDadGKD2HjD8ZOiFgJzBBUroFhlrFHenYe81o8CaFq4O7sAis2O2qrSDgYOHiJ7dtFluRomT00rSQT2am43QCUjPnqpJLc1N9uBmEFeS80= 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=VOqS2xMY; arc=none smtp.client-ip=91.218.175.186 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="VOqS2xMY" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1779766789; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MIys55gPtHxFJ6YYkvug3PyqOz22t6XWNtWG1R8os4w=; b=VOqS2xMYTt93PtKO1VfGDeSlnh+9Tjw856bjZFZc/Ckt9sKz1geFSMDUUDXxB3778ZsyaL pGFWQTP6HXiirfV8Oo1Au2LTOT6r/J0/6z2JSKSIBkQrMejmRj637jsJQHsoKAkHTct7Nj cDsIKs7h5e76PzZ5VauqdqC0djcq3wI= From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Qi Zheng , Alexandre Ghiti , Joshua Hahn , Harry Yoo , David Laight , Meta kernel team , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel test robot Subject: [PATCH v3 1/4] memcg: store node_id instead of pglist_data pointer Date: Mon, 25 May 2026 20:39:28 -0700 Message-ID: <20260526033931.1760588-2-shakeel.butt@linux.dev> In-Reply-To: <20260526033931.1760588-1-shakeel.butt@linux.dev> References: <20260526033931.1760588-1-shakeel.butt@linux.dev> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT The struct obj_stock_pcp stores a pointer to pglist_data for the slab stats cached on the cpu. On 64-bit machines, this costs 8 bytes. The pointer is not strictly required: NODE_DATA() can recover it from the node id. Replace cached_pgdat with int16_t node_id and use NUMA_NO_NODE as the "no stats cached" sentinel. At the moment all the archs limit MAX_NUMNODES to 1024 so int16_t is plenty; a BUILD_BUG_ON() makes sure we notice if that ever changes. Fixes: 01b9da291c49 ("mm: memcontrol: convert objcg to be per-memcg per-node type") Tested-by: kernel test robot Acked-by: Muchun Song Reviewed-by: Harry Yoo (Oracle) Acked-by: Qi Zheng Signed-off-by: Shakeel Butt --- Changes since v1 & v2: - Added tags in the commit message mm/memcontrol.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 13f5d4b2a78e..9bee9031171f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2022,7 +2022,7 @@ struct obj_stock_pcp { local_trylock_t lock; unsigned int nr_bytes; struct obj_cgroup *cached_objcg; - struct pglist_data *cached_pgdat; + int16_t node_id; int nr_slab_reclaimable_b; int nr_slab_unreclaimable_b; @@ -2032,6 +2032,7 @@ struct obj_stock_pcp { static DEFINE_PER_CPU_ALIGNED(struct obj_stock_pcp, obj_stock) = { .lock = INIT_LOCAL_TRYLOCK(lock), + .node_id = NUMA_NO_NODE, }; static DEFINE_MUTEX(percpu_charge_mutex); @@ -3162,6 +3163,13 @@ static void __account_obj_stock(struct obj_cgroup *objcg, { int *bytes; + /* + * Though at the moment MAX_NUMNODES <= 1024 in all archs but let's make + * sure it does not exceed S16_MAX otherwise we need to fix node_id type + * in struct obj_stock_pcp. + */ + BUILD_BUG_ON(MAX_NUMNODES >= S16_MAX); + if (!stock || READ_ONCE(stock->cached_objcg) != objcg) goto direct; @@ -3169,9 +3177,11 @@ static void __account_obj_stock(struct obj_cgroup *objcg, * Save vmstat data in stock and skip vmstat array update unless * accumulating over a page of vmstat data or when pgdat changes. */ - if (stock->cached_pgdat != pgdat) { + if (stock->node_id == NUMA_NO_NODE) { + stock->node_id = pgdat->node_id; + } else if (stock->node_id != pgdat->node_id) { /* Flush the existing cached vmstat data */ - struct pglist_data *oldpg = stock->cached_pgdat; + struct pglist_data *oldpg = NODE_DATA(stock->node_id); if (stock->nr_slab_reclaimable_b) { mod_objcg_mlstate(objcg, oldpg, NR_SLAB_RECLAIMABLE_B, @@ -3183,7 +3193,7 @@ static void __account_obj_stock(struct obj_cgroup *objcg, stock->nr_slab_unreclaimable_b); stock->nr_slab_unreclaimable_b = 0; } - stock->cached_pgdat = pgdat; + stock->node_id = pgdat->node_id; } bytes = (idx == NR_SLAB_RECLAIMABLE_B) ? &stock->nr_slab_reclaimable_b @@ -3279,19 +3289,21 @@ static void drain_obj_stock(struct obj_stock_pcp *stock) * Flush the vmstat data in current stock */ if (stock->nr_slab_reclaimable_b || stock->nr_slab_unreclaimable_b) { + struct pglist_data *oldpg = NODE_DATA(stock->node_id); + if (stock->nr_slab_reclaimable_b) { - mod_objcg_mlstate(old, stock->cached_pgdat, + mod_objcg_mlstate(old, oldpg, NR_SLAB_RECLAIMABLE_B, stock->nr_slab_reclaimable_b); stock->nr_slab_reclaimable_b = 0; } if (stock->nr_slab_unreclaimable_b) { - mod_objcg_mlstate(old, stock->cached_pgdat, + mod_objcg_mlstate(old, oldpg, NR_SLAB_UNRECLAIMABLE_B, stock->nr_slab_unreclaimable_b); stock->nr_slab_unreclaimable_b = 0; } - stock->cached_pgdat = NULL; + stock->node_id = NUMA_NO_NODE; } WRITE_ONCE(stock->cached_objcg, NULL); -- 2.53.0-Meta