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Message-Id: <20201217121303.13386-10-songmuchun@bytedance.com>
Date: Thu, 17 Dec 2020 20:13:01 +0800
From: Muchun Song <songmuchun@...edance.com>
To: corbet@....net, mike.kravetz@...cle.com, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com,
dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
viro@...iv.linux.org.uk, akpm@...ux-foundation.org,
paulmck@...nel.org, mchehab+huawei@...nel.org,
pawan.kumar.gupta@...ux.intel.com, rdunlap@...radead.org,
oneukum@...e.com, anshuman.khandual@....com, jroedel@...e.de,
almasrymina@...gle.com, rientjes@...gle.com, willy@...radead.org,
osalvador@...e.de, mhocko@...e.com, song.bao.hua@...ilicon.com,
david@...hat.com, naoya.horiguchi@....com
Cc: duanxiongchun@...edance.com, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org,
Muchun Song <songmuchun@...edance.com>
Subject: [PATCH v10 09/11] mm/hugetlb: Introduce nr_free_vmemmap_pages in the struct hstate
All the infrastructure is ready, so we introduce nr_free_vmemmap_pages
field in the hstate to indicate how many vmemmap pages associated with
a HugeTLB page that can be freed to buddy allocator. And initialize it
in the hugetlb_vmemmap_init(). This patch is actual enablement of the
feature.
Signed-off-by: Muchun Song <songmuchun@...edance.com>
Acked-by: Mike Kravetz <mike.kravetz@...cle.com>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
---
include/linux/hugetlb.h | 3 +++
mm/hugetlb.c | 1 +
mm/hugetlb_vmemmap.c | 33 +++++++++++++++++++++++++++++++++
mm/hugetlb_vmemmap.h | 10 ++++++----
4 files changed, 43 insertions(+), 4 deletions(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 7f47f0eeca3b..66d82ae7b712 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -492,6 +492,9 @@ struct hstate {
unsigned int nr_huge_pages_node[MAX_NUMNODES];
unsigned int free_huge_pages_node[MAX_NUMNODES];
unsigned int surplus_huge_pages_node[MAX_NUMNODES];
+#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
+ unsigned int nr_free_vmemmap_pages;
+#endif
#ifdef CONFIG_CGROUP_HUGETLB
/* cgroup control files */
struct cftype cgroup_files_dfl[7];
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index fea8a96dd718..6c02f49959fd 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3326,6 +3326,7 @@ void __init hugetlb_add_hstate(unsigned int order)
h->next_nid_to_free = first_memory_node;
snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
huge_page_size(h)/1024);
+ hugetlb_vmemmap_init(h);
parsed_hstate = h;
}
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 9e9bd458a3f5..3ebfe1706c77 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -166,6 +166,8 @@
* (last) level. So this type of HugeTLB page can be optimized only when its
* size of the struct page structs is greater than 2 pages.
*/
+#define pr_fmt(fmt) "HugeTLB: " fmt
+
#include "hugetlb_vmemmap.h"
/*
@@ -182,6 +184,12 @@ bool hugetlb_free_vmemmap_enabled;
static int __init early_hugetlb_free_vmemmap_param(char *buf)
{
+ /* We cannot optimize if a "struct page" crosses page boundaries. */
+ if ((!is_power_of_2(sizeof(struct page)))) {
+ pr_warn("cannot free vmemmap pages because \"struct page\" crosses page boundaries\n");
+ return 0;
+ }
+
if (!buf)
return -EINVAL;
@@ -220,3 +228,28 @@ void free_huge_page_vmemmap(struct hstate *h, struct page *head)
vmemmap_remap_free(vmemmap_addr + RESERVE_VMEMMAP_SIZE,
free_vmemmap_pages_size_per_hpage(h));
}
+
+void __init hugetlb_vmemmap_init(struct hstate *h)
+{
+ unsigned int nr_pages = pages_per_huge_page(h);
+ unsigned int vmemmap_pages;
+
+ if (!hugetlb_free_vmemmap_enabled)
+ return;
+
+ vmemmap_pages = (nr_pages * sizeof(struct page)) >> PAGE_SHIFT;
+ /*
+ * The head page and the first tail page are not to be freed to buddy
+ * allocator, the other pages will map to the first tail page, so they
+ * can be freed.
+ *
+ * Could RESERVE_VMEMMAP_NR be greater than @vmemmap_pages? It is true
+ * on some architectures (e.g. aarch64). See Documentation/arm64/
+ * hugetlbpage.rst for more details.
+ */
+ if (likely(vmemmap_pages > RESERVE_VMEMMAP_NR))
+ h->nr_free_vmemmap_pages = vmemmap_pages - RESERVE_VMEMMAP_NR;
+
+ pr_info("can free %d vmemmap pages for %s\n", h->nr_free_vmemmap_pages,
+ h->name);
+}
diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h
index b2c8d2f11d48..8fd9ae113dbd 100644
--- a/mm/hugetlb_vmemmap.h
+++ b/mm/hugetlb_vmemmap.h
@@ -13,17 +13,15 @@
#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
void alloc_huge_page_vmemmap(struct hstate *h, struct page *head);
void free_huge_page_vmemmap(struct hstate *h, struct page *head);
+void hugetlb_vmemmap_init(struct hstate *h);
/*
* How many vmemmap pages associated with a HugeTLB page that can be freed
* to the buddy allocator.
- *
- * Todo: Returns zero for now, which means the feature is disabled. We will
- * enable it once all the infrastructure is there.
*/
static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h)
{
- return 0;
+ return h->nr_free_vmemmap_pages;
}
#else
static inline void alloc_huge_page_vmemmap(struct hstate *h, struct page *head)
@@ -38,5 +36,9 @@ static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h)
{
return 0;
}
+
+static inline void hugetlb_vmemmap_init(struct hstate *h)
+{
+}
#endif /* CONFIG_HUGETLB_PAGE_FREE_VMEMMAP */
#endif /* _LINUX_HUGETLB_VMEMMAP_H */
--
2.11.0
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