On Fri, Jun 15, 2018 at 09:50:05PM -0700, Matthew Wilcox wrote:
> I wonder if (to address Michael's concern), you shouldn't instead use
> the first free chunk of pages to return the addresses of all the pages.
> ie something like this:
>
> __le64 *ret = NULL;
> unsigned int max = (PAGE_SIZE << order) / sizeof(__le64);
>
> for_each_populated_zone(zone) {
> spin_lock_irq(&zone->lock);
> for (mt = 0; mt < MIGRATE_TYPES; mt++) {
> list = &zone->free_area[order].free_list[mt];
> list_for_each_entry_safe(page, list, lru, ...) {
> if (index == size)
> break;
> addr = page_to_pfn(page) << PAGE_SHIFT;
> if (!ret) {
> list_del(...);
> ret = addr;
> }
> ret[index++] = cpu_to_le64(addr);
> }
> }
> spin_unlock_irq(&zone->lock);
> }
>
> return ret;
> }
>
> You'll need to return the page to the freelist afterwards, but free_pages()
> should take care of that.
Yes Wei already came up with the idea to stick this data into a
MAX_ORDER allocation. Are you sure just taking an entry off
the list like that has no bad side effects?
I have a vague memory someone complained that everyone
most go through get free pages/kmalloc, but I can't
find that anymore.
--
MST
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