Messages in this thread | | | From | "Kani, Toshi" <> | Subject | Re: [PATCH 1/1] resource: Fixed iomem resource release failed on release_mem_region_adjustable() when memory node or cpu node hot-remove. | Date | Mon, 25 Jun 2018 23:55:36 +0000 |
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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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