Re: kmem_cache_alloc fail with unable to handle paging request after pci hotplug remove.

[Mathias Nyman]

On 04.07.2016 18:21, Lukas Wunner wrote:
> On Mon, Jul 04, 2016 at 06:04:42PM +0300, Mathias Nyman wrote:
> > On 04.07.2016 17:25, Rafael J. Wysocki wrote:
> > > On Mon, Jul 4, 2016 at 4:26 PM, Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> wrote:
> > > > AceLan Kao can get his DELL XPS 13 laptop to hang by plugging/un-plugging
> > > > a USB 3.1 key via thunderbolt port.
> > > >
> > > > Allocating memory fails after this, always pointing to NULL pointer or
> > > > page request failing in get_freepointer() called by
> > > > kmalloc/kmem_cache_alloc.
> > > >
> > > > Unplugging a usb type-c device from the thunderbolt port on Alpine Ridge
> > > > based systems like this one will hotplug remove PCI bridges together
> > > > with the USB xhci controller behind them.
>
> Yes, that matches with the lspci output you've posted, the whole
> Thunderbolt controller is gone after unplug. Perhaps it's powered
> down? What does "lspci -vvvv -s 00:1d.6" say? (Does the root port
> still have a link to the Thunderbolt controller?)


"lspci -vvvv -s 00:1d.6" after unplug (on my working DELL XPS)


00:1d.6 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #15 (rev f1) (prog-if 00 [Normal decode])
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin C routed to IRQ 18
	Bus: primary=00, secondary=06, subordinate=3e, sec-latency=0
	I/O behind bridge: 00002000-00002fff
	Memory behind bridge: c4000000-da0fffff
	Prefetchable memory behind bridge: 0000000080000000-00000000a1ffffff
	Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
	BridgeCtl: Parity- SERR- NoISA- VGA- MAbort- >Reset- FastB2B-
		PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
	Capabilities: [40] Express (v2) Root Port (Slot+), MSI 00
		DevCap:	MaxPayload 256 bytes, PhantFunc 0
			ExtTag- RBE+
		DevCtl:	Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
			RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
			MaxPayload 128 bytes, MaxReadReq 128 bytes
		DevSta:	CorrErr+ UncorrErr- FatalErr- UnsuppReq- AuxPwr+ TransPend-
		LnkCap:	Port #15, Speed 8GT/s, Width x2, ASPM L0s L1, Exit Latency L0s <1us, L1 <16us
			ClockPM- Surprise- LLActRep+ BwNot+ ASPMOptComp+
		LnkCtl:	ASPM Disabled; RCB 64 bytes Disabled- CommClk+
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 2.5GT/s, Width x2, TrErr- Train- SlotClk+ DLActive- BWMgmt+ ABWMgmt-
		SltCap:	AttnBtn- PwrCtrl- MRL- AttnInd- PwrInd- HotPlug+ Surprise+
			Slot #18, PowerLimit 25.000W; Interlock- NoCompl+
		SltCtl:	Enable: AttnBtn- PwrFlt- MRL- PresDet+ CmdCplt- HPIrq- LinkChg-
			Control: AttnInd Unknown, PwrInd Unknown, Power- Interlock-
		SltSta:	Status: AttnBtn- PowerFlt- MRL- CmdCplt- PresDet- Interlock-
			Changed: MRL- PresDet- LinkState+
		RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal- PMEIntEna- CRSVisible-
		RootCap: CRSVisible-
		RootSta: PME ReqID 0000, PMEStatus- PMEPending-
		DevCap2: Completion Timeout: Range ABC, TimeoutDis+, LTR+, OBFF Not Supported ARIFwd+
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled ARIFwd-
		LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance De-emphasis: -6dB
		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete-, EqualizationPhase1-
			 EqualizationPhase2-, EqualizationPhase3-, LinkEqualizationRequest-
	Capabilities: [80] MSI: Enable- Count=1/1 Maskable- 64bit-
		Address: 00000000  Data: 0000
	Capabilities: [90] Subsystem: Dell Sunrise Point-H PCI Express Root Port
	Capabilities: [a0] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [100 v1] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO+ CmpltAbrt- UnxCmplt+ RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr+ BadTLP- BadDLLP- Rollover+ Timeout+ NonFatalErr+
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
		AERCap:	First Error Pointer: 00, GenCap- CGenEn- ChkCap- ChkEn-
	Capabilities: [140 v1] Access Control Services
		ACSCap:	SrcValid+ TransBlk+ ReqRedir+ CmpltRedir+ UpstreamFwd- EgressCtrl- DirectTrans-
		ACSCtl:	SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans-
	Capabilities: [200 v1] L1 PM Substates
		L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substates+
			  PortCommonModeRestoreTime=40us PortTPowerOnTime=10us
	Capabilities: [220 v1] #19
	Kernel driver in use: pcieport
	Kernel modules: shpchp


AceLan Kao, can you confirm your lspci output looks similar on the failing DELL XPS?

-Mathias