From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 8D0EC350A0D for ; Tue, 21 Oct 2025 19:28:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761074932; cv=none; b=gvEI5RLPIjxaSe1Pl7Ge3mAGmyiMzecnn1faq61g4H4/qGAMRGLqSBgLtw/9WKFuLYb02G3TNkoO58UWOoEZ41eyT0v57KZSYEjDkna0CMfmhvRVR7iohRpmt+UHv2Hnnesaa0mq9QEidFayoQ1D3LFxVWvrqzLQpUvLNxAHrcs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761074932; c=relaxed/simple; bh=5BCq9RRv7KamLtUB79/4SrvmAL0LwrRQ7PGI4CZ2MM8=; h=From:Message-ID:Date:MIME-Version:Subject:To:Cc:References: In-Reply-To:Content-Type; b=lYcn3Rpdnn1RRUp/SRB2he4vjPOlF04wMzVd2V8yOGQfRaP1gr2LQTkDrbuuCJvv71zsi8d8U865un+TWtkid7kP6VR/STphjVGxeih7/WIX5JuZlmRm75B1DXbLkzdWsrqTW01AK8ynNskl3Tj+Ah56bRfr/09NNQfxbpzt1D0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=BoB3rluM; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BoB3rluM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761074929; 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=OAcllF9nVIfCniwCIoLGKjAXFJuJdiDQqFfGC/k/Yfk=; b=BoB3rluMPOKjB4rHdV4VZTxG6jSvCCtj4bApw1ckBTPdZFe8zJIFQzjNs1uGgcy0SBQTNm Q7F17s5CAGOM9b1evWq/BPA0q9B48fea2rTPB1xLb9jeE4DTW/XW7GqsnnpDJ9xAdVPQtE Qchu0Ys9WMUyWZBJzoaJ/dODMCqcQfM= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-292-pKOLEutbOdS6mU35R9tdOw-1; Tue, 21 Oct 2025 15:28:47 -0400 X-MC-Unique: pKOLEutbOdS6mU35R9tdOw-1 X-Mimecast-MFC-AGG-ID: pKOLEutbOdS6mU35R9tdOw_1761074927 Received: by mail-qk1-f198.google.com with SMTP id af79cd13be357-88ea6169a96so403233785a.2 for ; Tue, 21 Oct 2025 12:28:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761074927; x=1761679727; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:user-agent:mime-version:date:message-id:from :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=OAcllF9nVIfCniwCIoLGKjAXFJuJdiDQqFfGC/k/Yfk=; b=Qds0a2DWfYORzdy0+3CNbWUviQZkFXpojQZim8Jrk+3gQjSY4x2xnlzv9xlJcfUYQg Tgd/o15qCa88LoSIm7HVY6mF2ru5gOTZcMaz3rz+vsdNA9VQCaR1CC+2jD+c6UsxgwCD buABF8lCNvUvMJwsVDaQ4SQyRtbVUqchjJ0xFE1LUjwmKz4ymmzWCc0+p0dd6TVy32H5 nWrXsCXft37DHV3hNKINSPsf9TMpd6oHoIwCVvXcdD0xtywiLx43Azz/IEpFD8c63tOG X5hu/3GpDEq70cYA0UYe8UdBoYMcgft4cx9kzJO1GhAU8MamZlBnQAQ3Pk1QEgrysS7+ m2zQ== X-Forwarded-Encrypted: i=1; AJvYcCVfRgFb3xV+QhjoxkFyBkmHSthrnlWpb64U81Igj8E3J3rg93jmRB38+ZPDsWfGABS8vx77kF5WPbOJJLM=@vger.kernel.org X-Gm-Message-State: AOJu0Yy07sAt1vudHrSgxVPlW64zVVKpq03SGlViBxwYxHimwPlb2Gdz MpzjydRu+7nAArDILpKrmRHj8yb35T+FIPl/IMeMLZZ1f8o2DdB54EkgrNZsdpePYp39JycXdi9 lf5rlkaKUVfKpr35voQp08cE96hIchmpbIqdg7dQHCAYUmpcqMplJNwCcYWnfjtOycg== X-Gm-Gg: ASbGncuD8E9OTcEFqToZ7ga+iF6gYiKzyPBZA1mzhpIBWQahP0owG7kpTp0dGgkLegQ wJ1ObWZf0jRdYhB/Yok/oS4krGlzTi7v2y+qcupwVd7gXafLDsfdjTLq6e5bcbnM8jTvfTXn4Mz +pHpyuhzPvAXT+hTRiOMCAvZUAtyDeIcfeUGuTDNbkDtJb/ZL5WLe0ATSnVehj6FP0YYnyhty9L 6GIt8GYAbfBL14qdUWpvVqVGq4R5QcBn7OUQvOxuc3T5UFPNwK9SS+n1JLM8JJYOblxiToQuhPJ ssI3XKqyOb0rHks2/LkWOMwvSNSwvOiM5yyunGpO/Dt4RIRvCPOdgelQvtWDWOne+708zQDx9Qu IQ1pulEprBRR8vsfgwHgpqroYpw1BY+MASDFZQ3d6aayUAQ== X-Received: by 2002:a05:620a:488e:b0:7e8:67b8:476 with SMTP id af79cd13be357-89070114f94mr2346437285a.57.1761074927220; Tue, 21 Oct 2025 12:28:47 -0700 (PDT) X-Google-Smtp-Source: AGHT+IG+u+8bH+lrXiYca/LtZ13ni/QSfiNRKtdF54+j0jtBiSwDvm50yRps0a3A4dxIJsM4iefKKw== X-Received: by 2002:a05:620a:488e:b0:7e8:67b8:476 with SMTP id af79cd13be357-89070114f94mr2346432285a.57.1761074926666; Tue, 21 Oct 2025 12:28:46 -0700 (PDT) Received: from ?IPV6:2601:600:947f:f020:85dc:d2b2:c5ee:e3c4? ([2601:600:947f:f020:85dc:d2b2:c5ee:e3c4]) by smtp.gmail.com with ESMTPSA id af79cd13be357-891cefba8f0sm817018785a.40.2025.10.21.12.28.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Oct 2025 12:28:46 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: Date: Tue, 21 Oct 2025 15:28:42 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 14/33] sched/isolation: Flush memcg workqueues on cpuset isolated partition change To: Frederic Weisbecker , LKML Cc: =?UTF-8?Q?Michal_Koutn=C3=BD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Danilo Krummrich , "David S . Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Simon Horman , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Will Deacon , cgroups@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org References: <20251013203146.10162-1-frederic@kernel.org> <20251013203146.10162-15-frederic@kernel.org> <364e084a-ef37-42ab-a2ae-5f103f1eb212@redhat.com> Content-Language: en-US In-Reply-To: <364e084a-ef37-42ab-a2ae-5f103f1eb212@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/21/25 3:16 PM, Waiman Long wrote: > On 10/13/25 4:31 PM, Frederic Weisbecker wrote: >> The HK_TYPE_DOMAIN housekeeping cpumask is now modifyable at runtime. In >> order to synchronize against memcg workqueue to make sure that no >> asynchronous draining is still pending or executing on a newly made >> isolated CPU, the housekeeping susbsystem must flush the memcg >> workqueues. >> >> However the memcg workqueues can't be flushed easily since they are >> queued to the main per-CPU workqueue pool. >> >> Solve this with creating a memcg specific pool and provide and use the >> appropriate flushing API. >> >> Acked-by: Shakeel Butt >> Signed-off-by: Frederic Weisbecker >> --- >>   include/linux/memcontrol.h |  4 ++++ >>   kernel/sched/isolation.c   |  2 ++ >>   kernel/sched/sched.h       |  1 + >>   mm/memcontrol.c            | 12 +++++++++++- >>   4 files changed, 18 insertions(+), 1 deletion(-) >> >> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h >> index 873e510d6f8d..001200df63cf 100644 >> --- a/include/linux/memcontrol.h >> +++ b/include/linux/memcontrol.h >> @@ -1074,6 +1074,8 @@ static inline u64 cgroup_id_from_mm(struct >> mm_struct *mm) >>       return id; >>   } >>   +void mem_cgroup_flush_workqueue(void); >> + >>   extern int mem_cgroup_init(void); >>   #else /* CONFIG_MEMCG */ >>   @@ -1481,6 +1483,8 @@ static inline u64 cgroup_id_from_mm(struct >> mm_struct *mm) >>       return 0; >>   } >>   +static inline void mem_cgroup_flush_workqueue(void) { } >> + >>   static inline int mem_cgroup_init(void) { return 0; } >>   #endif /* CONFIG_MEMCG */ >>   diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c >> index 95d69c2102f6..9ec365dea921 100644 >> --- a/kernel/sched/isolation.c >> +++ b/kernel/sched/isolation.c >> @@ -144,6 +144,8 @@ int housekeeping_update(struct cpumask *mask, >> enum hk_type type) >>         synchronize_rcu(); >>   +    mem_cgroup_flush_workqueue(); >> + >>       kfree(old); >>         return 0; >> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h >> index 8fac8aa451c6..8bfc0b4b133f 100644 >> --- a/kernel/sched/sched.h >> +++ b/kernel/sched/sched.h >> @@ -44,6 +44,7 @@ >>   #include >>   #include >>   #include >> +#include >>   #include >>   #include >>   #include >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index 1033e52ab6cf..1aa14e543f35 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -95,6 +95,8 @@ static bool cgroup_memory_nokmem __ro_after_init; >>   /* BPF memory accounting disabled? */ >>   static bool cgroup_memory_nobpf __ro_after_init; >>   +static struct workqueue_struct *memcg_wq __ro_after_init; >> + >>   static struct kmem_cache *memcg_cachep; >>   static struct kmem_cache *memcg_pn_cachep; >>   @@ -1975,7 +1977,7 @@ static void schedule_drain_work(int cpu, >> struct work_struct *work) >>   { >>       guard(rcu)(); >>       if (!cpu_is_isolated(cpu)) >> -        schedule_work_on(cpu, work); >> +        queue_work_on(cpu, memcg_wq, work); >>   } >>     /* >> @@ -5092,6 +5094,11 @@ void mem_cgroup_sk_uncharge(const struct sock >> *sk, unsigned int nr_pages) >>       refill_stock(memcg, nr_pages); >>   } >>   +void mem_cgroup_flush_workqueue(void) >> +{ >> +    flush_workqueue(memcg_wq); >> +} >> + >>   static int __init cgroup_memory(char *s) >>   { >>       char *token; >> @@ -5134,6 +5141,9 @@ int __init mem_cgroup_init(void) >>       cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, >> "mm/memctrl:dead", NULL, >>                     memcg_hotplug_cpu_dead); >>   +    memcg_wq = alloc_workqueue("memcg", 0, 0); > > Should we explicitly mark the memcg_wq as WQ_PERCPU even though I > think percpu is the default. The schedule_work_on() schedules work on > the system_percpu_wq. According to commit dadb3ebcf39 ("workqueue: WQ_PERCPU added to alloc_workqueue users"), the default may be changed to WQ_UNBOUND in the future. Cheers, Longman