From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6EF073DEDB2; Thu, 22 Jan 2026 16:14:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769098477; cv=none; b=rTj3tkJV3mLuekWAM6cwtwoqD2ejzg2Ed96lgatvcCVb25isCesnmPoRRxjdE+4SxlkmvdtgIPPCXnuwBniZP7X0+Fq/toQaJszt1tpoGBl12zaABckrRZChbgUjYkThUt5PahM0KrXTqTrrzoElrcmstO9mgQpfTu4R4G1X7Hc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769098477; c=relaxed/simple; bh=GrBl0GmB4EskXynUW6bH8pp7knC2vNONOphZtdopzwU=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=BhmWlMy/oh7sa1sNs7eYkOn1kM0aoWbW3yXohg8cTt9OgpbWy+yOuabpwy45vFBYn8zvtqtmxYnYb7XwrfMkjzgVso8n4239cjCOVN1Riy9Ix4o88vQgIrz7/heqGAqaLelYe4gteThNoOhrQUlH1tDCSXS1yJZ4rJNbTwUlZ5U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hpSHO+gh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hpSHO+gh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 911A5C116C6; Thu, 22 Jan 2026 16:14:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769098476; bh=GrBl0GmB4EskXynUW6bH8pp7knC2vNONOphZtdopzwU=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=hpSHO+ghl6+V/2A9sZcw97dKURkfaqnoh6fz57v7b/GtWXdfzXyy1Yby0UyhDjKvn 2W+GC9cq47CPQ+TyiGLDn45Swl8siTnsyFJ7on/xxPH49i5KT8MfQ3vmfWawrqtvS/ e0XgagEPSQy8S8MSzhOzpR/YURn2bktJ0b47/jNeBbGfV3QYbH+giEwsut0bvtVELK rpWCghXqtrEljSmHQ2BL3Elb1FNkrsKZfXYGCYyUHca2y5JEbBVE6ebqtSPa8N/6sE xvWIAneDy9J19bcgL4eE88SS3YXNHupckNIR5dM3vOtcnyqIgrEjM/GhgZcu+RgECE P9HBLzh+xmLPQ== Date: Thu, 22 Jan 2026 10:14:35 -0600 From: Bjorn Helgaas To: Frederic Weisbecker Cc: LKML , Michal =?utf-8?Q?Koutn=C3=BD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Chen Ridong , 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 , Waiman Long , 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 Subject: Re: [PATCH 17/33] PCI: Flush PCI probe workqueue on cpuset isolated partition change Message-ID: <20260122161435.GA1250260@bhelgaas> Precedence: bulk X-Mailing-List: netdev@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: <20260101221359.22298-18-frederic@kernel.org> On Thu, Jan 01, 2026 at 11:13:42PM +0100, Frederic Weisbecker wrote: > The HK_TYPE_DOMAIN housekeeping cpumask is now modifiable at runtime. In > order to synchronize against PCI probe works and make sure that no > asynchronous probing is still pending or executing on a newly isolated > CPU, the housekeeping subsystem must flush the PCI probe works. > > However the PCI probe works can't be flushed easily since they are > queued to the main per-CPU workqueue pool. > > Solve this with creating a PCI probe-specific pool and provide and use > the appropriate flushing API. > > Signed-off-by: Frederic Weisbecker Acked-by: Bjorn Helgaas > --- > drivers/pci/pci-driver.c | 17 ++++++++++++++++- > include/linux/pci.h | 3 +++ > kernel/sched/isolation.c | 2 ++ > 3 files changed, 21 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > index a6111140755c..b902d8adf9a5 100644 > --- a/drivers/pci/pci-driver.c > +++ b/drivers/pci/pci-driver.c > @@ -337,6 +337,8 @@ static int local_pci_probe(struct drv_dev_and_id *ddi) > return 0; > } > > +static struct workqueue_struct *pci_probe_wq; > + > struct pci_probe_arg { > struct drv_dev_and_id *ddi; > struct work_struct work; > @@ -407,7 +409,11 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev, > cpu = cpumask_any_and(cpumask_of_node(node), > wq_domain_mask); > if (cpu < nr_cpu_ids) { > - schedule_work_on(cpu, &arg.work); > + struct workqueue_struct *wq = pci_probe_wq; > + > + if (WARN_ON_ONCE(!wq)) > + wq = system_percpu_wq; > + queue_work_on(cpu, wq, &arg.work); > rcu_read_unlock(); > flush_work(&arg.work); > error = arg.ret; > @@ -425,6 +431,11 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev, > return error; > } > > +void pci_probe_flush_workqueue(void) > +{ > + flush_workqueue(pci_probe_wq); > +} > + > /** > * __pci_device_probe - check if a driver wants to claim a specific PCI device > * @drv: driver to call to check if it wants the PCI device > @@ -1762,6 +1773,10 @@ static int __init pci_driver_init(void) > { > int ret; > > + pci_probe_wq = alloc_workqueue("sync_wq", WQ_PERCPU, 0); > + if (!pci_probe_wq) > + return -ENOMEM; > + > ret = bus_register(&pci_bus_type); > if (ret) > return ret; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 864775651c6f..f14f467e50de 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1206,6 +1206,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus, > struct pci_ops *ops, void *sysdata, > struct list_head *resources); > int pci_host_probe(struct pci_host_bridge *bridge); > +void pci_probe_flush_workqueue(void); > int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax); > int pci_bus_update_busn_res_end(struct pci_bus *b, int busmax); > void pci_bus_release_busn_res(struct pci_bus *b); > @@ -2079,6 +2080,8 @@ static inline int pci_has_flag(int flag) { return 0; } > _PCI_NOP_ALL(read, *) > _PCI_NOP_ALL(write,) > > +static inline void pci_probe_flush_workqueue(void) { } > + > static inline struct pci_dev *pci_get_device(unsigned int vendor, > unsigned int device, > struct pci_dev *from) > diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c > index ec3f15164fd1..5239f556745d 100644 > --- a/kernel/sched/isolation.c > +++ b/kernel/sched/isolation.c > @@ -8,6 +8,7 @@ > * > */ > #include > +#include > #include "sched.h" > > enum hk_flags { > @@ -142,6 +143,7 @@ int housekeeping_update(struct cpumask *isol_mask) > > synchronize_rcu(); > > + pci_probe_flush_workqueue(); > mem_cgroup_flush_workqueue(); > vmstat_flush_workqueue(); > > -- > 2.51.1 >