netdev - Re: [PATCH 01/33] PCI: Prepare to protect against concurrent isolated cpuset change

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Message-ID: <20260107233956.GA453841@bhelgaas>
Date: Wed, 7 Jan 2026 17:39:56 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Frederic Weisbecker <frederic@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
	Michal Koutný <mkoutny@...e.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Chen Ridong <chenridong@...wei.com>,
	Danilo Krummrich <dakr@...nel.org>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Gabriele Monaco <gmonaco@...hat.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ingo Molnar <mingo@...hat.com>, Jakub Kicinski <kuba@...nel.org>,
	Jens Axboe <axboe@...nel.dk>, Johannes Weiner <hannes@...xchg.org>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Marco Crivellari <marco.crivellari@...e.com>,
	Michal Hocko <mhocko@...e.com>, Muchun Song <muchun.song@...ux.dev>,
	Paolo Abeni <pabeni@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>, Phil Auld <pauld@...hat.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Simon Horman <horms@...nel.org>, Tejun Heo <tj@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Vlastimil Babka <vbabka@...e.cz>, Waiman Long <longman@...hat.com>,
	Will Deacon <will@...nel.org>, cgroups@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-block@...r.kernel.org,
	linux-mm@...ck.org, linux-pci@...r.kernel.org,
	netdev@...r.kernel.org, Jinhui Guo <guojinhui.liam@...edance.com>
Subject: Re: [PATCH 01/33] PCI: Prepare to protect against concurrent
 isolated cpuset change

On Thu, Jan 08, 2026 at 12:30:13AM +0100, Frederic Weisbecker wrote:
> Le Wed, Jan 07, 2026 at 01:05:34PM -0600, Bjorn Helgaas a écrit :
> > On Thu, Jan 01, 2026 at 11:13:26PM +0100, Frederic Weisbecker wrote:
> > > HK_TYPE_DOMAIN will soon integrate cpuset isolated partitions and
> > > therefore be made modifiable at runtime. Synchronize against the cpumask
> > > update using RCU.
> > > 
> > > The RCU locked section includes both the housekeeping CPU target
> > > election for the PCI probe work and the work enqueue.
> > > 
> > > This way the housekeeping update side will simply need to flush the
> > > pending related works after updating the housekeeping mask in order to
> > > make sure that no PCI work ever executes on an isolated CPU. This part
> > > will be handled in a subsequent patch.
> > > 
> > > Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
> > 
> > Just FYI, Jinhui posted a series that touches this same code and might
> > need some coordination:
> > 
> >   https://lore.kernel.org/r/20260107175548.1792-1-guojinhui.liam@bytedance.com
> > 
> > IIUC, Jinhui's series adds some more NUMA smarts in the driver core
> > sync probing path and removes corresponding NUMA code from the PCI
> > core probe path.
> 
> I see. I can't drop my change, otherwise my series alone could crash
> dereferencing garbage. But Jinhui's series removes the need for my
> changes.
> 
> So an unpleasant conflict will happen in -next (and if everything
> goes well, further in next merge window) and it should be resolved
> with simply ignoring my changes and only apply those of Jinhui.

I don't want to derail your series, and I don't think you need to
change anything right now.  Jinhui's series is early and might not be
ready to merge until after yours, which should be fine.

Bjorn