On 8/5/2023 7:07 PM, Kemeng Shi wrote:
We call isolate_freepages_block in strict mode, continuous pages in
pageblock will be isolated if isolate_freepages_block successed.
Then pfn + isolated will point to start of next pageblock to scan
no matter how many pageblocks are isolated in isolate_freepages_block.
Use pfn + isolated as start of next pageblock to scan to simplify the
iteration.
IIUC, the isolate_freepages_block() can isolate high-order free pages,
which means the pfn + isolated can be larger than the block_end_pfn. So
in your patch, the 'block_start_pfn' and 'block_end_pfn' can be in
different pageblocks, that will break pageblock_pfn_to_page().
Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
---
mm/compaction.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 684f6e6cd8bc..8d7d38073d30 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -733,21 +733,11 @@ isolate_freepages_range(struct compact_control *cc,
block_end_pfn = pageblock_end_pfn(pfn);
for (; pfn < end_pfn; pfn += isolated,
- block_start_pfn = block_end_pfn,
- block_end_pfn += pageblock_nr_pages) {
+ block_start_pfn = pfn,
+ block_end_pfn = pfn + pageblock_nr_pages) {
/* Protect pfn from changing by isolate_freepages_block */
unsigned long isolate_start_pfn = pfn;
- /*
- * pfn could pass the block_end_pfn if isolated freepage
- * is more than pageblock order. In this case, we adjust
- * scanning range to right one.
- */
- if (pfn >= block_end_pfn) {
- block_start_pfn = pageblock_start_pfn(pfn);
- block_end_pfn = pageblock_end_pfn(pfn);
- }
-
block_end_pfn = min(block_end_pfn, end_pfn);
if (!pageblock_pfn_to_page(block_start_pfn,
