On 16.08.24 06:06, 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; In fact, we don't need to migrate page in page range isolation, for memory offline path, there is do_migrate_range() to move the pages. For contig allocation, there is another __alloc_contig_migrate_range() after isolation to migrate the pages. So fix issue by skipping the __alloc_contig_migrate_range() in isolate_single_pageblock(). Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity") Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> --- mm/page_isolation.c | 28 +++------------------------- 1 file changed, 3 insertions(+), 25 deletions(-) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 39fb8c07aeb7..7e04047977cf 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -403,30 +403,8 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, unsigned long head_pfn = page_to_pfn(head); unsigned long nr_pages = compound_nr(head);- if (head_pfn + nr_pages <= boundary_pfn) {- pfn = head_pfn + nr_pages; - continue; - } - -#if defined CONFIG_COMPACTION || defined CONFIG_CMA - if (PageHuge(page)) { - int page_mt = get_pageblock_migratetype(page); - struct compact_control cc = { - .nr_migratepages = 0, - .order = -1, - .zone = page_zone(pfn_to_page(head_pfn)), - .mode = MIGRATE_SYNC, - .ignore_skip_hint = true, - .no_set_skip_hint = true, - .gfp_mask = gfp_flags, - .alloc_contig = true, - }; - INIT_LIST_HEAD(&cc.migratepages); - - ret = __alloc_contig_migrate_range(&cc, head_pfn, - head_pfn + nr_pages, page_mt); - if (ret) - goto failed;
But won't this break alloc_contig_range() then? I would have expected that you have to special-case here on the migration reason (MEMORY_OFFLINE).
I remember some dirty details when we're trying to allcoate with a single pageblock for alloc_contig_range().
Note that memory offlining always covers pageblocks large than MAX_ORDER chunks (which implies full pageblocks) but alloc_contig_range() + CMA might only cover (parts of) single pageblocks.
Hoping Zi Yan can review :) -- Cheers, David / dhildenb
