linux-kernel - Re: [PATCH] arm64: PCI: fix memleak when calling pci

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Message-ID: <BYAPR18MB267959E6FE4BEF38D0A4611EC5280@BYAPR18MB2679.namprd18.prod.outlook.com>
Date:   Mon, 7 Sep 2020 10:51:21 +0000
From:   George Cherian <gcherian@...vell.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Yang Yingliang <yangyingliang@...wei.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "will.deacon@....com" <will.deacon@....com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "guohanjun@...wei.com" <guohanjun@...wei.com>
Subject: Re: [PATCH] arm64: PCI: fix memleak when calling pci_iomap/unmap()



> -----Original Message-----
> From: Catalin Marinas <catalin.marinas@....com>
> Sent: Monday, September 7, 2020 4:16 PM
> To: Yang Yingliang <yangyingliang@...wei.com>
> Cc: linux-kernel@...r.kernel.org; linux-pci@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; will.deacon@....com; bhelgaas@...gle.com;
> George Cherian <gcherian@...vell.com>; guohanjun@...wei.com
> Subject: Re: [PATCH] arm64: PCI: fix memleak when calling
> pci_iomap/unmap()
> 
> 
> ----------------------------------------------------------------------
> On Sat, Sep 05, 2020 at 10:48:11AM +0800, Yang Yingliang wrote:
> > diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c index
> > 1006ed2d7c604..ddfa1c53def48 100644
> > --- a/arch/arm64/kernel/pci.c
> > +++ b/arch/arm64/kernel/pci.c
> > @@ -217,4 +217,9 @@ void pcibios_remove_bus(struct pci_bus *bus)
> >  	acpi_pci_remove_bus(bus);
> >  }
> >
> > +void pci_iounmap(struct pci_dev *dev, void __iomem *addr) {
> > +	iounmap(addr);
> > +}
> > +EXPORT_SYMBOL(pci_iounmap);
> 
> So, what's wrong with the generic pci_iounmap() implementation?
> Shouldn't it call iounmap() already?
Since ARM64 selects CONFIG_GENERIC_PCI_IOMAP and not
CONFIG_GENERIC_IOMAP,  the pci_iounmap function is reduced to a NULL
function. Due to this, even the managed release variants or even the explicit
pci_iounmap calls doesn't really remove the mappings leading to leak.

-George
https://lkml.org/lkml/2020/8/20/28

> 
> --
> Catalin