On 2024/8/20 16:42, David Hildenbrand wrote:
On 20.08.24 05:26, Kefeng Wang wrote:
The gigantic page size may larger than memory block size, so memory
offline always fails in this case after commit b2c9e2fbba32 ("mm: make
alloc_contig_range work at pageblock granularity"),
offline_pages
start_isolate_page_range
start_isolate_page_range(isolate_before=true)
isolate [isolate_start, isolate_start + pageblock_nr_pages)
start_isolate_page_range(isolate_before=false)
isolate [isolate_end - pageblock_nr_pages, isolate_end) pageblock
__alloc_contig_migrate_range
isolate_migratepages_range
isolate_migratepages_block
isolate_or_dissolve_huge_page
if (hstate_is_gigantic(h))
return -ENOMEM;
[ 15.815756] memory offlining [mem 0x3c0000000-0x3c7ffffff] failed
due to failure to isolate range
Gigantic PageHuge is bigger than a pageblock, but since it is freed as
order-0 pages, its pageblocks after being freed will get to the right
free list. There is no need to have special handling code for them in
start_isolate_page_range(). For both alloc_contig_range() and memory
offline cases, the migration code after start_isolate_page_range() will
be able to migrate gigantic PageHuge when possible.
Let's clean up start_isolate_page_range() and fix the aforementioned
memory offline failure issue all together.
Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock
granularity")
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
...
+ if (head_pfn + nr_pages <= boundary_pfn ||
+ PageHuge(page)) {
I'm wondering if we should have here some kind of WARN_ON_ONCE if
PageLRU + "spans more than a single pageblock" check.
Then we could catch whenever we would have !hugetlb LRU folios that span
more than a single pageblock.
/*
* We cannot currently handle movable (LRU) folios that span more than
* a single pageblock. hugetlb folios are fine, though.
*/
WARN_ON_ONCE(PageLRU(page) && nr_pages > pageblock_nr_pages
This should be already covered by following VM_WRAN,
VM_WARN_ON_ONCE_PAGE(PageLRU(page), page); // only hint when head_pfn
+ nr_pages > boundary_pfn ( boundary_pfn is pageblock aligned)
VM_WARN_ON_ONCE_PAGE(__PageMovable(page), page);
But now I realized something I previously missed: We are only modifying
behavior of hugetlb folios ... stupid misleading "PageHuge" check :)
So that would be independent of this change.
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
