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

[David Hildenbrand]

On 23.03.21 12:06, Andy Shevchenko wrote:
> On Mon, Mar 22, 2021 at 05:01:58PM +0100, 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
>
> "...fixes..." effectively means to me that Fixes tag should be provided.

We can certainly add, although it doesn't really affect the running 
kernel, but only crashdumps taken in the kdump kernel:

Fixes: ebf71552bb0e ("virtio-mem: Add parent resource for all added 
"System RAM"")
Fixes: c221c0b0308f ("device-dax: "Hotplug" persistent memory for use 
like normal RAM")

Thanks

--
Thanks,

David / dhildenb