linux-kernel - [PATCH] mm: set pageblock_order to HPAGE_PMD_ORDER in case with !CONFIG_HUGETLB

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Date: Fri,  5 Apr 2024 20:24:16 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: akpm@...ux-foundation.org
Cc: mgorman@...hsingularity.net,
	vbabka@...e.cz,
	baolin.wang@...ux.alibaba.com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] mm: set pageblock_order to HPAGE_PMD_ORDER in case with !CONFIG_HUGETLB_PAGE but THP enabled

As Vlastimil suggested in previous discussion[1], it doesn't make sense to set
pageblock_order as MAX_PAGE_ORDER when hugetlbfs is not enabled and THP is enabled.
Instead, it should be set to HPAGE_PMD_ORDER.

[1] https://lore.kernel.org/all/76457ec5-d789-449b-b8ca-dcb6ceb12445@suse.cz/
Suggested-by: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
---
 include/linux/pageblock-flags.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index 3f2409b968ec..547e82cdc89a 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -28,7 +28,7 @@ enum pageblock_bits {
 	NR_PAGEBLOCK_BITS
 };
 
-#ifdef CONFIG_HUGETLB_PAGE
+#if defined(CONFIG_HUGETLB_PAGE)
 
 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
 
@@ -45,7 +45,11 @@ extern unsigned int pageblock_order;
 
 #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
 
-#else /* CONFIG_HUGETLB_PAGE */
+#elif defined(CONFIG_TRANSPARENT_HUGEPAGE)
+
+#define pageblock_order		min_t(unsigned int, HPAGE_PMD_ORDER, MAX_PAGE_ORDER)
+
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 /* If huge pages are not used, group by MAX_ORDER_NR_PAGES */
 #define pageblock_order		MAX_PAGE_ORDER
-- 
2.39.3