linux-kernel - Re: [PATCH] PCI: pciehp: Prevent child devices from doing RPM on PCIe Link Down

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Message-ID: <20231019143504.GA25140@wunner.de>
Date:   Thu, 19 Oct 2023 16:35:04 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Ricky WU <ricky_wu@...ltek.com>
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>,
        Tony Luck <tony.luck@...el.com>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI: pciehp: Prevent child devices from doing RPM on
 PCIe Link Down

On Thu, Oct 19, 2023 at 01:49:50AM +0000, Ricky WU wrote:
> [    0.267813] pci 0000:00:1c.0: [8086:a33c] type 01 class 0x060400

Cannon Lake PCH Root Port

> [    0.275241] pci 0000:01:00.0: [10ec:5261] type 00 class 0xff0000
> [    0.275315] pci 0000:01:00.0: reg 0x10: [mem 0xa3b00000-0xa3b00fff]
> [    0.275782] pci 0000:01:00.0: supports D1 D2
> [    0.275784] pci 0000:01:00.0: PME# supported from D1 D2 D3hot D3cold
> [    0.276490] pci 0000:00:1c.0: PCI bridge to [bus 01]

Device below Root Port is initially a Realtek RTS5261 card reader.

> [    0.395968] pcieport 0000:00:1c.0: PME: Signaling with IRQ 122
> [    0.396009] pcieport 0000:00:1c.0: pciehp: Slot #8 AttnBtn- PwrCtrl- MRL- AttnInd- PwrInd- HotPlug+ Surprise+ Interlock- NoCompl+ IbPresDis- LLActRep+

Root Port is hotplug-capable.

> [   43.180701] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Down
> [   43.180709] pcieport 0000:00:1c.0: pciehp: Slot(8): Card not present
> [   44.403768] pcieport 0000:00:1c.0: pciehp: Slot(8): Card present
> [   44.403772] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Up
> [   44.540631] pci 0000:01:00.0: [15b7:5007] type 00 class 0x010802

Card reader is unplugged and replaced by SanDisk SN530 NVMe SSD.

> [   51.682628] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Down
> [   51.716800] nvme0n1: detected capacity change from 495050752 to 0
> [   51.793382] pcieport 0000:00:1c.0: pciehp: Slot(8): Card present
> [   51.793392] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Up
> [   51.928633] pci 0000:01:00.0: [10ec:5261] type 00 class 0xff0000

NVMe SSD replaced by the card reader again.

> [   54.872928] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Down
> [   56.146581] pcieport 0000:00:1c.0: pciehp: Slot(8): Card present
> [   56.146584] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Up
> [   56.284632] pci 0000:01:00.0: [15b7:5007] type 00 class 0x010802

Card reader replaced by NVMe SSD, second time.

> [   60.635845] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Down
> [   60.676842] nvme0n1: detected capacity change from 495050752 to 0
> [   60.748953] pcieport 0000:00:1c.0: pciehp: Slot(8): Card present
> [   60.748958] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Up
> [   60.884619] pci 0000:01:00.0: [10ec:5261] type 00 class 0xff0000

NVMe SSD replaced by the card reader, second time.

> [   63.898861] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Down
> [   63.912118] BUG: unable to handle page fault for address: ffffb24d403e5010

Card reader replaced with NVMe SSD, third time.

So it took three tries to reproduce the page fault.

Thanks for the log, the issue is a little less murky now.
But it's still unclear what the root cause is and thus
what the proper solution is.  I think this needs more
in-depth debugging, see my previous e-mail.

Hope that helps!  Thanks,

Lukas