linux-kernel - Re: [PATCH] PCI: pciehp: Fix system hang on resume after hot-unplug during suspend

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Message-ID: <ZvvX5i95MpWrru4_@wunner.de>
Date: Tue, 1 Oct 2024 13:07:18 +0200
From: Lukas Wunner <lukas@...ner.de>
To: AceLan Kao <acelan.kao@...onical.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: pciehp: Fix system hang on resume after hot-unplug
 during suspend

On Mon, Sep 30, 2024 at 11:27:28AM +0800, AceLan Kao wrote:
> Lukas Wunner <lukas@...ner.de> 2024 9 27 5:28
> > there is a known issue
> > that a deadlock may occur when hot-removing nested PCIe switches (which is
> > what you've got here).  Keith Busch recently re-discovered the issue.
> > You may want to try if the hang goes away if you apply this patch:
> >
> > https://lore.kernel.org/all/20240612181625.3604512-2-kbusch@meta.com/
> >
> > If it does go away then at least we know what the root cause is.
> 
> Yes, the 2 patches work.

Okay so you can't reproduce the issue with those patches?

That would mean 9d573d19547b ("PCI: pciehp: Detect device replacement
during system sleep") isn't the culprit, whew!


> > The patch is a bit hackish, but there's an ongoing effort to tackle the
> > problem more thoroughly:
> >
> > https://lore.kernel.org/all/20240722151936.1452299-1-kbusch@meta.com/
> > https://lore.kernel.org/all/20240827192826.710031-1-kbusch@meta.com/
> 
> v2 can't be applied clearly, so I made some changes.
> And this series doesn't work for me.

Okay, I'll look at those patches separately.

Thanks,

Lukas