Re: [PATCH v1 1/3] kernel/resource: make walk_system_ram_res() find all busy IORESOURCE_SYSTEM_RAM resources

[Andy Shevchenko]

On Tue, Mar 23, 2021 at 10:40:33AM +0100, David Hildenbrand wrote:
> On 22.03.21 17:01, David Hildenbrand wrote:
> > It used to be true that we can have busy system RAM only on the first level
> > in the resourc tree. However, this is no longer holds for driver-managed
> > system RAM (i.e., added via dax/kmem and virtio-mem), which gets added on
> > lower levels.
> > 
> > We have two users of walk_system_ram_res(), which currently only
> > consideres the first level:
> > a) kernel/kexec_file.c:kexec_walk_resources() -- We properly skip
> >     IORESOURCE_SYSRAM_DRIVER_MANAGED resources via
> >     locate_mem_hole_callback(), so even after this change, we won't be
> >     placing kexec images onto dax/kmem and virtio-mem added memory. No
> >     change.
> > b) arch/x86/kernel/crash.c:fill_up_crash_elf_data() -- we're currently
> >     not adding relevant ranges to the crash elf info, resulting in them
> >     not getting dumped via kdump.
> > 
> > This change fixes loading a crashkernel via kexec_file_load() and including
> > dax/kmem and virtio-mem added System RAM in the crashdump on x86-64. Note
> > that e.g,, arm64 relies on memblock data and, therefore, always considers
> > all added System RAM already.
> > 
> > Let's find all busy IORESOURCE_SYSTEM_RAM resources, making the function
> > behave like walk_system_ram_range().
> > 
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> > Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > Cc: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> > Cc: Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
> 
> ^ My copy-paste action when creating the cc list slipped in a duplicate  SO
> in all 3 patches. I can resend if desired.

I think to address my comments you will need to resend anyway (as v2).

-- 
With Best Regards,
Andy Shevchenko