mm/compaction: fix the range to pageblock_pfn_to_page()

mm/compaction: fix the range to pageblock_pfn_to_page()

The function pageblock_pfn_to_page() must confirm that the target range is
contained entirely within the current zone.

Originally, when pageblock_pfn_to_page() was introduced by commit
7d49d8868336, it operated on a single range, [pfn, block_end_pfn], for
both range checking and isolation.

However, commit e1409c325fdc ("mm/compaction: pass only pageblock aligned
range to pageblock_pfn_to_page") changed this behavior, causing the
function to operate on two different ranges:

[block_start_pfn, block_end_pfn] is used to check if the range is in the
same zone.

[pfn, block_end_pfn] is used for page isolation.

This split logic fails when start_pfn < zone_start_pfn, even if both are
within the same pageblock.  In this scenario, the checking range
[block_start_pfn, block_end_pfn] is used, which incorrectly misses the
pages before zone_start_pfn.

         start_pfn     zone_start_pfn
    +----+-------------+-------------------+
    block_start_pfn                        block_end_pfn

This oversight allows the range check to pass, even though the isolation
step ([pfn, block_end_pfn]) may attempt to isolate pages belonging to two
different zones.

To fix this, we should revert to using the same range ([block_start_pfn,
block_end_pfn]) for both checking and isolation in each iteration.

Link: https://lkml.kernel.org/r/20251002033140.24462-3-richard.weiyang@gmail.com
Fixes: e1409c325fdc ("mm/compaction: pass only pageblock aligned range to pageblock_pfn_to_page")
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>