linux-kernel - [PATCH] mm/huge_memory: disable thp if thp page size is too large

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Date:   Thu, 30 Sep 2021 10:14:15 +0800
From:   Hao Peng <flyingpenghao@...il.com>
To:     akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mm/huge_memory: disable thp if thp page size is too large

From: Peng Hao <flyingpeng@...cent.com>

After seting the page size to 64k on ARM64, the supported huge page
size is 512M and 1TB. Therefore, if the thp is enabled, the size
of the thp is 512M. In this case, min_free_kbytes will be too large.

On an arm64 server with 64G memory, the page size is 64k, with thp
enabled.
cat /proc/sys/vm/min_free_kbytes
3335104

Therefore, when judging whether to enable thp by default, consider
the size of thp.

Signed-off-by: Peng Hao <flyingpeng@...cent.com>
---
 mm/huge_memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5e9ef0fc261e..03c7f571b3ae 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -437,7 +437,7 @@ static int __init hugepage_init(void)
         * where the extra memory used could hurt more than TLB overhead
         * is likely to save.  The admin can still enable it through /sys.
         */
-       if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
+       if (totalram_pages() < (512 << (HPAGE_PMD_SHIFT - PAGE_SHIFT))) {
                transparent_hugepage_flags = 0;
                return 0;
        }
--
2.27.0