On Sun, 30 Jul 2023 01:43:50 +0800 Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> wrote:
> Commit 9fcd6d2e052ee ("mm, compaction: skip compound pages by order in
> free scanner") skiped compound pages to save iterations and limit blockpfn
> to reach outside of page block in case of bogus compound_order. While this
> also limit pfnblock outside page block in case a buddy page with order
> higher than page block is found. After this, isolate_freepages_range will
> fail unexpectedly as it will fail to isolate the page block which was
> isolated successfully by high order buddy page in previous page block
> and abort the free page isolation.
>
> Fix this by allow blockpfn outside of pageblock in case of high order
> buddy page.
>
> ...
>
> @@ -1418,7 +1420,7 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn)
> isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false);
>
> /* Skip this pageblock in the future as it's full or nearly full */
> - if (start_pfn == end_pfn && !cc->no_set_skip_hint)
> + if (start_pfn >= end_pfn && !cc->no_set_skip_hint)
> set_pageblock_skip(page);
> }
>
This needed alteration for mm-unstable changes:
@@ -1441,7 +1443,7 @@ fast_isolate_around(struct compact_contr
isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false);
/* Skip this pageblock in the future as it's full or nearly full */
- if (start_pfn == end_pfn)
+ if (start_pfn >= end_pfn)
set_pageblock_skip(page);
return;
