linux-kernel - [RFC PATCH v2 27/30] mm: thp: make PUD THP size public.

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Date:   Mon, 28 Sep 2020 13:54:25 -0400
From:   Zi Yan <zi.yan@...t.com>
To:     linux-mm@...ck.org
Cc:     "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Roman Gushchin <guro@...com>, Rik van Riel <riel@...riel.com>,
        Matthew Wilcox <willy@...radead.org>,
        Shakeel Butt <shakeelb@...gle.com>,
        Yang Shi <shy828301@...il.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Michal Hocko <mhocko@...e.com>,
        David Hildenbrand <david@...hat.com>,
        William Kucharski <william.kucharski@...cle.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        John Hubbard <jhubbard@...dia.com>,
        David Nellans <dnellans@...dia.com>,
        linux-kernel@...r.kernel.org, Zi Yan <ziy@...dia.com>
Subject: [RFC PATCH v2 27/30] mm: thp: make PUD THP size public.

From: Zi Yan <ziy@...dia.com>

User can access the PUD THP size via
`cat /sys/kernel/mm/transparent_hugepage/hpage_pud_size`. This is
similar to make PMD THP size public.

Signed-off-by: Zi Yan <ziy@...dia.com>
---
 Documentation/admin-guide/mm/transhuge.rst |  1 +
 mm/huge_memory.c                           | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index b2acd0d395ca..11b173c2650e 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -159,6 +159,7 @@ Some userspace (such as a test program, or an optimized memory allocation
 library) may want to know the size (in bytes) of a transparent hugepage::
 
 	cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
+	cat /sys/kernel/mm/transparent_hugepage/hpage_pud_size
 
 khugepaged will be automatically started when
 transparent_hugepage/enabled is set to "always" or "madvise, and it'll
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1965753b31a2..20ecffc27396 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -340,12 +340,25 @@ static ssize_t hpage_pmd_size_show(struct kobject *kobj,
 static struct kobj_attribute hpage_pmd_size_attr =
 	__ATTR_RO(hpage_pmd_size);
 
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+static ssize_t hpage_pud_size_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", HPAGE_PUD_SIZE);
+}
+static struct kobj_attribute hpage_pud_size_attr =
+	__ATTR_RO(hpage_pud_size);
+#endif
+
 static struct attribute *hugepage_attr[] = {
 	&enabled_attr.attr,
 	&enabled_pud_thp_attr.attr,
 	&defrag_attr.attr,
 	&use_zero_page_attr.attr,
 	&hpage_pmd_size_attr.attr,
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+	&hpage_pud_size_attr.attr,
+#endif
 #ifdef CONFIG_SHMEM
 	&shmem_enabled_attr.attr,
 #endif
-- 
2.28.0