From: Bjorn Helgaas <helgaas@kernel.org>
To: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
Cc: Klaus Kudielka <klaus.kudielka@gmail.com>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] PCI: Do not size non-existing prefetchable window
Date: Mon, 27 Oct 2025 18:12:22 -0500 [thread overview]
Message-ID: <20251027231222.GA1487591@bhelgaas> (raw)
In-Reply-To: <20251027132423.8841-1-ilpo.jarvinen@linux.intel.com>
On Mon, Oct 27, 2025 at 03:24:23PM +0200, Ilpo Järvinen wrote:
> pbus_size_mem() should only be called for bridge windows that exist but
> __pci_bus_size_bridges() may point 'pref' to a resource that does not
> exist (has zero flags) in case of non-root buses.
>
> When prefetchable bridge window does not exist, the same
> non-prefetchable bridge window is sized more than once which may result
> in duplicating entries into the realloc_head list. Duplicated entries
> are shown in this log and trigger a WARN_ON() because realloc_head had
> residual entries after the resource assignment algorithm:
>
> pci 0000:00:03.0: [11ab:6820] type 01 class 0x060400 PCIe Root Port
> pci 0000:00:03.0: PCI bridge to [bus 00]
> pci 0000:00:03.0: bridge window [io 0x0000-0x0fff]
> pci 0000:00:03.0: bridge window [mem 0x00000000-0x000fffff]
> pci 0000:00:03.0: bridge window [mem 0x00200000-0x003fffff] to [bus 02] add_size 200000 add_align 200000
> pci 0000:00:03.0: bridge window [mem 0x00200000-0x003fffff] to [bus 02] add_size 200000 add_align 200000
> pci 0000:00:03.0: bridge window [mem 0xe0000000-0xe03fffff]: assigned
> pci 0000:00:03.0: PCI bridge to [bus 02]
> pci 0000:00:03.0: bridge window [mem 0xe0000000-0xe03fffff]
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at drivers/pci/setup-bus.c:2373 pci_assign_unassigned_root_bus_resources+0x1bc/0x234
>
> Check resource flags of 'pref' and only size the prefetchable window if
> the resource has the IORESOURCE_PREFETCH flag.
>
> Fixes: ae88d0b9c57f ("PCI: Use pbus_select_window_for_type() during mem window sizing")
> Link: https://lore.kernel.org/linux-pci/51e8cf1c62b8318882257d6b5a9de7fdaaecc343.camel@gmail.com/
> Reported-by: Klaus Kudielka <klaus.kudielka@gmail.com>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Since ae88d0b9c57f appeared in v6.18-rc1, this looks like v6.18
material, right?
Applied to pci/for-linus for v6.18 on that assumption, thanks!
> ---
> drivers/pci/setup-bus.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 362ad108794d..7cb6071cff7a 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -1604,7 +1604,7 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
> pbus_size_io(bus, realloc_head ? 0 : additional_io_size,
> additional_io_size, realloc_head);
>
> - if (pref) {
> + if (pref && (pref->flags & IORESOURCE_PREFETCH)) {
> pbus_size_mem(bus,
> IORESOURCE_MEM | IORESOURCE_PREFETCH |
> (pref->flags & IORESOURCE_MEM_64),
>
> base-commit: 2f2c7254931f41b5736e3ba12aaa9ac1bbeeeb92
> --
> 2.39.5
>
next prev parent reply other threads:[~2025-10-27 23:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-27 13:24 [PATCH 1/1] PCI: Do not size non-existing prefetchable window Ilpo Järvinen
2025-10-27 17:45 ` Klaus Kudielka
2025-10-27 17:55 ` Ilpo Järvinen
2025-10-27 23:12 ` Bjorn Helgaas [this message]
2025-10-27 23:15 ` Ilpo Järvinen
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