On 11/27/24 16:52, Matthew Wilcox wrote:
> On Wed, Nov 27, 2024 at 04:07:01PM +0100, David Hildenbrand wrote:
>> I think we discussed in v1 or v2 that page isolation should be taught about that.
>>
>> Likely we want something like:
>>
>> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
>> index 7e04047977cfe..7db2f79b39f0d 100644
>> --- a/mm/page_isolation.c
>> +++ b/mm/page_isolation.c
>> @@ -101,6 +101,8 @@ static struct page *has_unmovable_pages(unsigned long start_pfn, unsigned long e
>> * because their page->_refcount is zero at all time.
>> */
>> if (!page_ref_count(page)) {
>> + if (PageSlab(page))
>> + return page;
>> if (PageBuddy(page))
>> pfn += (1 << buddy_order(page)) - 1;
>
> Ah, for order 0 slabs! I got caught up thinking that slabs would be
> caught by the earlier PageTransCompound() check. But that's also a
> bit messy since we know that __folio_test_movable() can sometimes appear
> true on slab pages. So I'm tempted to hoist this way up to between the
> check for ZONE_MOVABLE and PageHuge.
That should work. Are you going to try advancing by folio_nr_pages() in that
case as well?
