mm: page_alloc: use the correct THP order for THP PCP

Commit 44042b449872 ("mm/page_alloc: allow high-order pages to be stored
on the per-cpu lists") extends the PCP allocator to store THP pages, and
it determines whether to cache THP pages in PCP by comparing with
pageblock_order.  But the pageblock_order is not always equal to THP
order.  It might also be MAX_PAGE_ORDER, which could prevent PCP from
caching THP pages.

Therefore, using HPAGE_PMD_ORDER instead to determine the need for caching
THP for PCP will fix this issue

Link: https://lkml.kernel.org/r/a25c9e14cd03907d5978b60546a69e6aa3fc2a7d.1712151833.git.baolin.wang@linux.alibaba.com
Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Barry Song <baohua@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 07c21774a722174eae56ea4374a9f70400bde817..cbe3f695eda9b15f13ad2da50524b8340f1a25da 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -506,7 +506,7 @@ static inline unsigned int order_to_pindex(int migratetype, int order)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
        if (order > PAGE_ALLOC_COSTLY_ORDER) {
-               VM_BUG_ON(order != pageblock_order);
+               VM_BUG_ON(order != HPAGE_PMD_ORDER);
                return NR_LOWORDER_PCP_LISTS;
        }
 #else
@@ -522,7 +522,7 @@ static inline int pindex_to_order(unsigned int pindex)
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
        if (pindex == NR_LOWORDER_PCP_LISTS)
-               order = pageblock_order;
+               order = HPAGE_PMD_ORDER;
 #else
        VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);
 #endif
@@ -535,7 +535,7 @@ static inline bool pcp_allowed_order(unsigned int order)
        if (order <= PAGE_ALLOC_COSTLY_ORDER)
                return true;
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-       if (order == pageblock_order)
+       if (order == HPAGE_PMD_ORDER)
                return true;
 #endif
        return false;