mm/compaction: correctly return failure with bogus compound_order in strict mode

In strict mode, we should return 0 if there is any hole in pageblock.  If
we successfully isolated pages at beginning at pageblock and then have a
bogus compound_order outside pageblock in next page.  We will abort search
loop with blockpfn > end_pfn.  Although we will limit blockpfn to end_pfn,
we will treat it as a successful isolation in strict mode as blockpfn is
not < end_pfn and return partial isolated pages.  Then
isolate_freepages_range may success unexpectly with hole in isolated
range.

Link: https://lkml.kernel.org/r/20230901155141.249860-4-shikemeng@huaweicloud.com


Fixes: 9fcd6d2e ("mm, compaction: skip compound pages by order in free scanner")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>