On 13 Jan 2022, at 9:57, Zi Yan wrote: > On 12 Jan 2022, at 6:01, David Hildenbrand wrote: > >> On 05.01.22 22:47, Zi Yan wrote: >>> From: Zi Yan <ziy@xxxxxxxxxx> >>> >>> In isolate_migratepages_block(), a !PageLRU tail page can be encountered >>> when the page is larger than a pageblock. Use compound head page for the >>> checks inside and skip the entire compound page when isolation succeeds. >>> >> >> This will currently never happen, due to the way we always isolate >> MAX_ORDER -1 ranges, correct? > > You are right. > >> >> Better note that in the patch description, because currently it reads >> like it's an actual fix "can be encountered". >> > > Will do. This is a preparation patch for the upcoming commits. I will drop this one too. Like you mentioned in [1], there are no non-lru migratable compound pages. This is only used by my local test code. [1] https://lore.kernel.org/linux-mm/970ca2a4-416d-7e8f-37c7-510c5b050f4b@xxxxxxxxxx/ > >>> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx> >>> --- >>> mm/compaction.c | 10 +++++++--- >>> 1 file changed, 7 insertions(+), 3 deletions(-) >>> >>> diff --git a/mm/compaction.c b/mm/compaction.c >>> index b4e94cda3019..ad9053fbbe06 100644 >>> --- a/mm/compaction.c >>> +++ b/mm/compaction.c >>> @@ -979,19 +979,23 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, >>> * Skip any other type of page >>> */ >>> if (!PageLRU(page)) { >>> + struct page *head = compound_head(page); >>> /* >>> * __PageMovable can return false positive so we need >>> * to verify it under page_lock. >>> */ >>> - if (unlikely(__PageMovable(page)) && >>> - !PageIsolated(page)) { >>> + if (unlikely(__PageMovable(head)) && >>> + !PageIsolated(head)) { >>> if (locked) { >>> unlock_page_lruvec_irqrestore(locked, flags); >>> locked = NULL; >>> } >>> >>> - if (!isolate_movable_page(page, isolate_mode)) >>> + if (!isolate_movable_page(head, isolate_mode)) { >>> + low_pfn += (1 << compound_order(head)) - 1 - (page - head); >>> + page = head; >>> goto isolate_success; >>> + } >>> } >>> >>> goto isolate_fail; >> >> >> -- >> Thanks, >> >> David / dhildenb > > > -- > Best Regards, > Yan, Zi -- Best Regards, Yan, Zi
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