From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) (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 1D7B733A9D1; Tue, 3 Mar 2026 03:09:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772507367; cv=none; b=WMNArqKYG837UgMfLkg1dLl55kQ1oSpXNNljCcfXYcbNqaZyQPtvE+Gs/S2q+r6athViIoGm0qd4CVD7Ktrkg6q+TUX76D43MqAak4+mZ3f5m2I5vB0gX/f3gYCXG2VX6/ZBEqndDPHTQP5i1jfPWxt82mK7NdXiUQOR0Csa9u8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772507367; c=relaxed/simple; bh=efVxg2nJsWIH0vvBmC1ejzUCEKnuP8Oq7UWgHL0TMM0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=U53uWJ2Gk6QhG4C8GetrIKOjmBLL/VYe73cHDXJLY9uLJI4z9TZN2XioCI6BkoY14BB1RDiB6AGdmQPTWQ3xxVOKQ1mG77vPhR+og6A8mS74XW4oOmGsUfPlyjCq8wG8lBGSxt2CNa7tJZ1wcrINNsQmKp5JceVif2K8ndltULY= 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=QyVeESPa; arc=none smtp.client-ip=91.218.175.188 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="QyVeESPa" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1772507363; 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=SBs9bcabgCEvuY4u0v9/Zsg1qM7B1u6PtJQeoLsqsQQ=; b=QyVeESPaWFJLoQzS37FHot8bE0Mv+NxgIBjalY7avmEkv0ZeizppPT+OoVZJEzwHQOX2IT U3njDt7ffGXBk2bUNFimSYNg+4wknqLnu0vTTmgV+E782nA1Mhg9gqTLtOr3BeTQhLjTRB J/nsZ1VHUXl8ykXDxlffhIrVdjuTb7I= Date: Tue, 3 Mar 2026 11:08:56 +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 update 29/32] mm: memcontrol: prepare for reparenting non-hierarchical stats To: Yosry Ahmed Cc: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@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: <20260228072556.31793-1-qi.zheng@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 Hi Yosry, On 3/2/26 11:53 PM, Yosry Ahmed wrote: > [..] >> @@ -763,6 +851,64 @@ unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx) >> #endif >> return x; >> } >> + >> +static void __mod_memcg_state(struct mem_cgroup *memcg, >> + enum memcg_stat_item idx, int val) >> +{ >> + int i = memcg_stats_index(idx); >> + int cpu; >> + >> + if (mem_cgroup_disabled()) >> + return; >> + >> + cpu = get_cpu(); >> + >> + this_cpu_add(memcg->vmstats_percpu->state[i], val); >> + val = memcg_state_val_in_pages(idx, val); >> + memcg_rstat_updated(memcg, val, cpu); >> + trace_mod_memcg_state(memcg, idx, val); >> + >> + put_cpu(); >> +} >> + >> +static void __mod_memcg_lruvec_state(struct lruvec *lruvec, >> + enum node_stat_item idx, int val) >> +{ >> + struct mem_cgroup_per_node *pn; >> + struct mem_cgroup *memcg; >> + int i = memcg_stats_index(idx); >> + int cpu; >> + >> + pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); >> + memcg = pn->memcg; >> + >> + cpu = get_cpu(); >> + >> + /* Update memcg */ >> + this_cpu_add(memcg->vmstats_percpu->state[i], val); >> + >> + /* Update lruvec */ >> + this_cpu_add(pn->lruvec_stats_percpu->state[i], val); >> + >> + val = memcg_state_val_in_pages(idx, val); >> + memcg_rstat_updated(memcg, val, cpu); >> + trace_mod_memcg_lruvec_state(memcg, idx, val); >> + >> + put_cpu(); >> +} > > I don't think we should end up with two copies of > __mod_memcg_state/mod_memcg_state() and > __mod_memcg_lruvec_state/mod_memcg_lruvec_state(). I meant to refactor > mod_memcg_state() to call __mod_memcg_state(), where the latter does > not call get_non_dying_memcg_{start/end}(). Same for > mod_memcg_lruvec_state(). Okay, like the following? But this would require modifications to [PATCH v5 31/32]. If there are no problems, I will send the updated patch to [PATCH v5 29/32] and [PATCH v5 31/32]. diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e927530156fee..3d9e2cfad5b12 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -528,7 +528,8 @@ unsigned long lruvec_page_state_local(struct lruvec *lruvec, #ifdef CONFIG_MEMCG_V1 static void __mod_memcg_lruvec_state(struct lruvec *lruvec, - enum node_stat_item idx, int val); + enum node_stat_item idx, int val, + bool reparent); void reparent_memcg_lruvec_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent, int idx) @@ -544,8 +545,8 @@ void reparent_memcg_lruvec_state_local(struct mem_cgroup *memcg, struct lruvec *parent_lruvec = mem_cgroup_lruvec(parent, NODE_DATA(nid)); unsigned long value = lruvec_page_state_local(child_lruvec, idx); - __mod_memcg_lruvec_state(child_lruvec, idx, -value); - __mod_memcg_lruvec_state(parent_lruvec, idx, value); + __mod_memcg_lruvec_state(child_lruvec, idx, -value, true); + __mod_memcg_lruvec_state(parent_lruvec, idx, value, true); } } #endif @@ -831,14 +832,9 @@ static inline void get_non_dying_memcg_end(void) } #endif -/** - * mod_memcg_state - update cgroup memory statistics - * @memcg: the memory cgroup - * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item - * @val: delta to add to the counter, can be negative - */ -void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, - int val) +static void __mod_memcg_state(struct mem_cgroup *memcg, + enum memcg_stat_item idx, int val, + bool reparent) { int i = memcg_stats_index(idx); int cpu; @@ -846,24 +842,38 @@ void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, if (mem_cgroup_disabled()) return; - if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) + if (!reparent && WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) return; cpu = get_cpu(); - memcg = get_non_dying_memcg_start(memcg); + if (!reparent) + memcg = get_non_dying_memcg_start(memcg); this_cpu_add(memcg->vmstats_percpu->state[i], val); val = memcg_state_val_in_pages(idx, val); memcg_rstat_updated(memcg, val, cpu); - get_non_dying_memcg_end(); + if (!reparent) + get_non_dying_memcg_end(); trace_mod_memcg_state(memcg, idx, val); put_cpu(); } +/** + * mod_memcg_state - update cgroup memory statistics + * @memcg: the memory cgroup + * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item + * @val: delta to add to the counter, can be negative + */ +void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, + int val) +{ + __mod_memcg_state(memcg, idx, val, false); +} + #ifdef CONFIG_MEMCG_V1 /* idx can be of type enum memcg_stat_item or node_stat_item. */ unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx) @@ -882,51 +892,6 @@ unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx) return x; } -static void __mod_memcg_state(struct mem_cgroup *memcg, - enum memcg_stat_item idx, int val) -{ - int i = memcg_stats_index(idx); - int cpu; - - if (mem_cgroup_disabled()) - return; - - cpu = get_cpu(); - - this_cpu_add(memcg->vmstats_percpu->state[i], val); - val = memcg_state_val_in_pages(idx, val); - memcg_rstat_updated(memcg, val, cpu); - trace_mod_memcg_state(memcg, idx, val); - - put_cpu(); -} - -static void __mod_memcg_lruvec_state(struct lruvec *lruvec, - enum node_stat_item idx, int val) -{ - struct mem_cgroup_per_node *pn; - struct mem_cgroup *memcg; - int i = memcg_stats_index(idx); - int cpu; - - pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); - memcg = pn->memcg; - - cpu = get_cpu(); - - /* Update memcg */ - this_cpu_add(memcg->vmstats_percpu->state[i], val); - - /* Update lruvec */ - this_cpu_add(pn->lruvec_stats_percpu->state[i], val); - - val = memcg_state_val_in_pages(idx, val); - memcg_rstat_updated(memcg, val, cpu); - trace_mod_memcg_lruvec_state(memcg, idx, val); - - put_cpu(); -} - void reparent_memcg_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent, int idx) { @@ -936,14 +901,14 @@ void reparent_memcg_state_local(struct mem_cgroup *memcg, if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) return; - __mod_memcg_state(memcg, idx, -value); - __mod_memcg_state(parent, idx, value); + __mod_memcg_state(memcg, idx, -value, true); + __mod_memcg_state(parent, idx, value, true); } #endif -static void mod_memcg_lruvec_state(struct lruvec *lruvec, - enum node_stat_item idx, - int val) +static void __mod_memcg_lruvec_state(struct lruvec *lruvec, + enum node_stat_item idx, int val, + bool reparent) { struct pglist_data *pgdat = lruvec_pgdat(lruvec); struct mem_cgroup_per_node *pn; @@ -951,7 +916,7 @@ static void mod_memcg_lruvec_state(struct lruvec *lruvec, int i = memcg_stats_index(idx); int cpu; - if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) + if (!reparent && WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) return; pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); @@ -959,8 +924,10 @@ static void mod_memcg_lruvec_state(struct lruvec *lruvec, cpu = get_cpu(); - memcg = get_non_dying_memcg_start(memcg); - pn = memcg->nodeinfo[pgdat->node_id]; + if (!reparent) { + memcg = get_non_dying_memcg_start(memcg); + pn = memcg->nodeinfo[pgdat->node_id]; + } /* Update memcg */ this_cpu_add(memcg->vmstats_percpu->state[i], val); @@ -969,13 +936,21 @@ static void mod_memcg_lruvec_state(struct lruvec *lruvec, val = memcg_state_val_in_pages(idx, val); memcg_rstat_updated(memcg, val, cpu); - get_non_dying_memcg_end(); + if (!reparent) + get_non_dying_memcg_end(); trace_mod_memcg_lruvec_state(memcg, idx, val); put_cpu(); } +static void mod_memcg_lruvec_state(struct lruvec *lruvec, + enum node_stat_item idx, + int val) +{ + __mod_memcg_lruvec_state(lruvec, idx, val, false); +} + /** * mod_lruvec_state - update lruvec memory statistics * @lruvec: the lruvec >