Re: [PATCH v4 5/8] x86/mm: Use pagetable_free()

Baolu Lu
2025-09-19T05:34:16Z

On 9/6/25 04:11, Dave Hansen wrote:
> On 9/5/25 11:41, Jason Gunthorpe wrote:
>>> --- a/arch/x86/mm/init_64.c
>>> +++ b/arch/x86/mm/init_64.c
>>> @@ -1013,7 +1013,7 @@ static void __meminit free_pagetable(struct page *page, int order)
>>> free_reserved_pages(page, nr_pages);
>>> #endif
>>> } else {
>>> - free_pages((unsigned long)page_address(page), order);
>>> + pagetable_free(page_ptdesc(page));
>>> }
>>> }
>> Er.. So if bootmem happens to be under the table and we happen to free
>> it due to memory hotplug we don't go through the SVA fixing path?
>>
>> Seems wrong??
>
> On second thought...
>
> Yes, freeing bootmem with no SVA fixing is wrong. It should be fixed.
> Period. But, it's wrong one time for something super rare: memory unplug
> of memory that was present at boot. It also can't be triggered by
> unprivileged users.
>
> As-is, this series fixes vfree(). That path is not nearly rare, can
> happen an arbitrary number of times on each boot, and might even be
> triggered by folks that are less than root.
>
> So I kinda think we should just make clear that this series leaves
> _some_ holes, but I do think it should go in mostly as-is.
>

Okay, I will put this in the commit message and update this series with
a new version.

Thanks,
baolu