From: Johannes Weiner hannes@cmpxchg.org
mainline inclusion from mainline-v6.10-rc1 commit 2dd482ba627de15d67f0c0ed445133c8ae9b201b category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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When a block is partially outside the zone of the cursor page, the function cuts the range to the pivot page instead of the zone start. This can leave large parts of the block behind, which encourages incompatible page mixing down the line (ask for one type, get another), and thus long-term fragmentation.
This triggers reliably on the first block in the DMA zone, whose start_pfn is 1. The block is stolen, but everything before the pivot page (which was often hundreds of pages) is left on the old list.
Link: https://lkml.kernel.org/r/20240320180429.678181-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner hannes@cmpxchg.org Reviewed-by: Vlastimil Babka vbabka@suse.cz Tested-by: Baolin Wang baolin.wang@linux.alibaba.com Cc: David Hildenbrand david@redhat.com Cc: "Huang, Ying" ying.huang@intel.com Cc: Mel Gorman mgorman@techsingularity.net Cc: Zi Yan ziy@nvidia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_alloc.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7e3593318813..a101f5f550dc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1661,9 +1661,15 @@ int move_freepages_block(struct zone *zone, struct page *page, start_pfn = pageblock_start_pfn(pfn); end_pfn = pageblock_end_pfn(pfn) - 1;
- /* Do not cross zone boundaries */ + /* + * The caller only has the lock for @zone, don't touch ranges + * that straddle into other zones. While we could move part of + * the range that's inside the zone, this call is usually + * accompanied by other operations such as migratetype updates + * which also should be locked. + */ if (!zone_spans_pfn(zone, start_pfn)) - start_pfn = pfn; + return 0; if (!zone_spans_pfn(zone, end_pfn)) return 0;