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Date: Wed, 9 Sep 2020 12:36:13 +0100 From: Lorenzo Pieralisi <lorenzo.pieralisi@....com> To: Catalin Marinas <catalin.marinas@....com> Cc: George Cherian <gcherian@...vell.com>, Yang Yingliang <yangyingliang@...wei.com>, "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() On Mon, Sep 07, 2020 at 12:21:19PM +0100, Catalin Marinas wrote: > + Lorenzo > > On Mon, Sep 07, 2020 at 10:51:21AM +0000, George Cherian wrote: > > Catalin Marinas <catalin.marinas@....com> wrote: > > > 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. > > Ah, I missed the fact that pci_iounmap() depends on a different > config option. > > > https://lkml.org/lkml/2020/8/20/28 > > So is this going to be fixed in the generic code? That would be my > preference. > > A problem with the iounmap() in the proposed patch is that the region > may have been an I/O port, so we could end up unmapping the I/O space. It boils down to finding a way to match a VA to a BAR resource so that we can mirror on pci_iounmap() what's done in pci_iomap_range() (ie check BAR resource flags to define how/if to unmap them), that would do as a generic pci_iounmap() implementation. In the pcim_* interface that looks easy to do, in the non-managed case ideas welcome - at the end of the day the deal is having a way to detect in a generic way what's behind a void __iomem *. Lorenzo
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