Re: vm_area at addr ffffffffc0800000 is not marked as VM_IOREMAP

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On Thu, Mar 7, 2024 at 9:54 AM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> On Thu, Mar 7, 2024 at 9:42 AM Miguel Ojeda
> <miguel.ojeda.sandonis@xxxxxxxxx> wrote:
> >
> > Hi arm64/bpf/pci,
> >
> > In today's next-20240307 with a defconfig LLVM=1 I am seeing [1] under
> > QEMU virt, i.e. from
> > https://lore.kernel.org/all/20240305030516.41519-2-alexei.starovoitov@xxxxxxxxx/
> > applied to the bpf-next tree.
> >
> > Cheers,
> > Miguel
> >
> > [1]
> >
> > [    0.425177] pci-host-generic 4010000000.pcie: host bridge
> > /pcie@10000000 ranges:
> > [    0.425886] pci-host-generic 4010000000.pcie:       IO
> > 0x003eff0000..0x003effffff -> 0x0000000000
> > [    0.426534] pci-host-generic 4010000000.pcie:      MEM
> > 0x0010000000..0x003efeffff -> 0x0010000000
> > [    0.426764] pci-host-generic 4010000000.pcie:      MEM
> > 0x8000000000..0xffffffffff -> 0x8000000000
> > [    0.427324] ------------[ cut here ]------------
> > [    0.427456] vm_area at addr ffffffffc0800000 is not marked as VM_IOREMAP
> > [    0.427944] WARNING: CPU: 0 PID: 1 at mm/vmalloc.c:315
> > ioremap_page_range+0x25c/0x2bc
>
> Great. Thanks for flagging.
> Looks like this check found some misuse of ioremap_page_range.
>
> Note that without marking the address range as VM_IOREMAP
> the vread_iter() will be bulk reading over IO and might
> cause hard hangs and what not.
> pci drivers need to mark their range as VM_IOREMAP.
> That was the reason for the warning.
>
> I'll try to figure out which piece of code missed passing
> VM_IOREMAP into vm_area.
> I'm not familiar with pci, so help is greatly appreciated.

Ok. I think I figured it out.
Please try the attached patch.

Attachment: 0001-mm-Enforce-range-of-ioremap_page_range-when-it-s-ins.patch
Description: Binary data


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