Re: arm64: WARNING: at mm/vmalloc.c:315 ioremap_page_range

[Alexei Starovoitov <alexei.starovoitov@gmail.com>]

On Fri, Mar 8, 2024 at 6:24 AM Naresh Kamboju <naresh.kamboju@linaro.org> wrote:
>
> On Fri, 8 Mar 2024 at 17:34, Arnd Bergmann <arnd@arndb.de> wrote:
> >
> > On Fri, Mar 8, 2024, at 12:53, Naresh Kamboju wrote:
> > > The following warning was noticed while boot arm and arm64 devices.
> > > The below log is extracted from arm64 ROCK Pi 4B while booting and
> > > another issue is kernel oops noticed while testing selftests:  kvm:
> > > memslot_perf_test.
> > >
> > > 1) WARNING: CPU: 1 PID: 201 at mm/vmalloc.c:315 ioremap_page_range
> > > 2)  Unable to handle kernel NULL pointer dereference at virtual address
> > >   Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
> > >   Kernel panic - not syncing: Oops: Fatal exception in interrupt
> > >
> > > Please find steps to reproduce, logs and config file links below.
> > >
> > > Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>
> <trim>
>
> > The warning was added by commit 3e49a866c9dc ("mm: Enforce
> > VM_IOREMAP flag and range in ioremap_page_range.").
> >
> > This indeed uses a special memory area at a fixed physical address,
> > but I don't see where the vm_struct comes from.
>
> Thanks for your explanation.
>
> > No idea here, but it seems unrelated to the first one.
>
> I will reproduce this issue a few more times and get back to you.

See the proposed fix:
https://lore.kernel.org/bpf/CAADnVQLP=dxBb+RiMGXoaCEuRrbK387J6B+pfzWKF_F=aRgCPQ@mail.gmail.com/

but Christoph believes a different approach is necessary:
https://lore.kernel.org/bpf/Zeso7eNj1sBhH5zY@infradead.org/