On Fri, 2018-06-22 at 18:19 -0500, Bjorn Helgaas wrote:
> [+cc Toshi]
>
> On Fri, Jun 22, 2018 at 08:01:38PM +0800, guomin chen wrote:
> > We've got a bug report indicating the hot-remove node resource
> > release failed,when the memory on this node is divided into
> > several sections.because the release_mem_region_adjustable()
> > can only release one resource that must be [start,end].
>
> Can you please include a URL for the bug report? That's useful for
> additional details and gives hints about how future changes in this
> area might be tested.
>
> release_mem_region_adjustable() and the only call to it were added
> by Toshi (cc'd):
>
> 825f787bb496 ("resource: add release_mem_region_adjustable()")
> fe74ebb106a5 ("mm: change __remove_pages() to call release_mem_region_adjustable()")
>
> > In my case, the BIOS supports faulty memory isolation. if BIOS
> > detected bad memory block, the BIOS will isolates this badblock.
> > And set this badblock memory to EfiUnusableMemory in EFI memory map
> > base on UEFI 2.7 spec.For example in my system, the memory range on
> > node2 is [mem 0x0000080000000000-0x00000807ffffffff].but the BIOS
> > detected the [8004e000000-8004e0fffff] is a badblock memory.
> > So the memory on node2 seem like this:
> > 80000000000-8004dffffff : System RAM
> > 8004e000000-8004e0fffff : Unusable memory
> > 8004e100000-807ffffffff : System RAM
> >
> > Now, when offline the cpu node2,the kernel will try to release
> > ioresource [mem 0x0000080000000000-0x00000807ffffffff]. at this
> > time, the kernel will release failed,and output error message:
> > "Unable to release resource <0x0000080000000000-0x00000807ffffffff>
> > (-22)".
Hmm... this BIO implementation does not sound right to me. When EFI
memory map has a hole, ACPI memory object should have the same hole in
its resource info. If so, this node2 memory hot-delete would have
requested a deletion of 2 separate System RAM ranges, not a single range
including this hole. This is also important for memory hot-add. ACPI
memory object needs to describe this hole in order for the OS to avoid
adding this badblock memory.
Thanks,
-Toshi
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