linux-kernel - [PATCH 5/6] x86, mm: skip 1G range if the range doesn't span PUD

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Date:   Tue, 12 Feb 2019 10:12:14 +0800
From:   Wei Yang <richardw.yang@...ux.intel.com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org
Cc:     dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.or,
        tglx@...utronix.de, Wei Yang <richardw.yang@...ux.intel.com>
Subject: [PATCH 5/6] x86, mm: skip 1G range if the range doesn't span PUD

If the 1G aligned pfn exceed the range, we are sure there won't be
possible 1G range. so we can just jump to split 2M range directly.

Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>
---
 arch/x86/mm/init.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 87275238dbb0..cbb105388f24 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -394,10 +394,10 @@ static int __meminit split_mem_range(struct map_range *mr,
 	 * Range (B):
 	 * big page (2M) range
 	 */
-	start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
 	end_pfn = round_up(pfn, PFN_DOWN(PUD_SIZE));
 	if (end_pfn > round_down(limit_pfn, PFN_DOWN(PMD_SIZE)))
-		end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
+		goto no_1G_range;
+	start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
 	if (start_pfn < end_pfn) {
 		nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
 				page_size_mask & (1<<PG_LEVEL_2M));
@@ -416,6 +416,7 @@ static int __meminit split_mem_range(struct map_range *mr,
 				 ((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G)));
 		pfn = end_pfn;
 	}
+no_1G_range:
 #endif
 
 	/*
-- 
2.19.1