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From: Muchun Song <songmuchun@bytedance.com>
To: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com,
	dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, viro@zeniv.linux.org.uk,
	akpm@linux-foundation.org, paulmck@kernel.org,
	pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org,
	oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de,
	almasrymina@google.com, rientjes@google.com, willy@infradead.org,
	osalvador@suse.de, mhocko@suse.com, song.bao.hua@hisilicon.com,
	david@redhat.com, naoya.horiguchi@nec.com,
	joao.m.martins@oracle.com
Cc: duanxiongchun@bytedance.com, fam.zheng@bytedance.com,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	Muchun Song <songmuchun@bytedance.com>,
	Miaohe Lin <linmiaohe@huawei.com>,
	Chen Huang <chenhuang5@huawei.com>,
	Bodeddula Balasubramaniam <bodeddub@amazon.com>
Subject: [PATCH v20 3/9] mm: hugetlb: gather discrete indexes of tail page
Date: Thu, 15 Apr 2021 16:39:59 +0800
Message-ID: <20210415084005.25049-4-songmuchun@bytedance.com> (raw)
In-Reply-To: <20210415084005.25049-1-songmuchun@bytedance.com>

For HugeTLB page, there are more metadata to save in the struct page.
But the head struct page cannot meet our needs, so we have to abuse
other tail struct page to store the metadata. In order to avoid
conflicts caused by subsequent use of more tail struct pages, we can
gather these discrete indexes of tail struct page. In this case, it
will be easier to add a new tail page index later.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Tested-by: Chen Huang <chenhuang5@huawei.com>
Tested-by: Bodeddula Balasubramaniam <bodeddub@amazon.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 include/linux/hugetlb.h        | 21 +++++++++++++++++++--
 include/linux/hugetlb_cgroup.h | 19 +++++++++++--------
 2 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 09f1fd12a6fa..0abed7e766b8 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -29,6 +29,23 @@ typedef struct { unsigned long pd; } hugepd_t;
 #include <linux/shm.h>
 #include <asm/tlbflush.h>
 
+/*
+ * For HugeTLB page, there are more metadata to save in the struct page. But
+ * the head struct page cannot meet our needs, so we have to abuse other tail
+ * struct page to store the metadata. In order to avoid conflicts caused by
+ * subsequent use of more tail struct pages, we gather these discrete indexes
+ * of tail struct page here.
+ */
+enum {
+	SUBPAGE_INDEX_SUBPOOL = 1,	/* reuse page->private */
+#ifdef CONFIG_CGROUP_HUGETLB
+	SUBPAGE_INDEX_CGROUP,		/* reuse page->private */
+	SUBPAGE_INDEX_CGROUP_RSVD,	/* reuse page->private */
+	__MAX_CGROUP_SUBPAGE_INDEX = SUBPAGE_INDEX_CGROUP_RSVD,
+#endif
+	__NR_USED_SUBPAGE,
+};
+
 struct hugepage_subpool {
 	spinlock_t lock;
 	long count;
@@ -626,13 +643,13 @@ extern unsigned int default_hstate_idx;
  */
 static inline struct hugepage_subpool *hugetlb_page_subpool(struct page *hpage)
 {
-	return (struct hugepage_subpool *)(hpage+1)->private;
+	return (void *)page_private(hpage + SUBPAGE_INDEX_SUBPOOL);
 }
 
 static inline void hugetlb_set_page_subpool(struct page *hpage,
 					struct hugepage_subpool *subpool)
 {
-	set_page_private(hpage+1, (unsigned long)subpool);
+	set_page_private(hpage + SUBPAGE_INDEX_SUBPOOL, (unsigned long)subpool);
 }
 
 static inline struct hstate *hstate_file(struct file *f)
diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
index 0bff345c4bc6..0b8d1fdda3a1 100644
--- a/include/linux/hugetlb_cgroup.h
+++ b/include/linux/hugetlb_cgroup.h
@@ -21,15 +21,16 @@ struct hugetlb_cgroup;
 struct resv_map;
 struct file_region;
 
+#ifdef CONFIG_CGROUP_HUGETLB
 /*
  * Minimum page order trackable by hugetlb cgroup.
  * At least 4 pages are necessary for all the tracking information.
- * The second tail page (hpage[2]) is the fault usage cgroup.
- * The third tail page (hpage[3]) is the reservation usage cgroup.
+ * The second tail page (hpage[SUBPAGE_INDEX_CGROUP]) is the fault
+ * usage cgroup. The third tail page (hpage[SUBPAGE_INDEX_CGROUP_RSVD])
+ * is the reservation usage cgroup.
  */
-#define HUGETLB_CGROUP_MIN_ORDER	2
+#define HUGETLB_CGROUP_MIN_ORDER order_base_2(__MAX_CGROUP_SUBPAGE_INDEX + 1)
 
-#ifdef CONFIG_CGROUP_HUGETLB
 enum hugetlb_memory_event {
 	HUGETLB_MAX,
 	HUGETLB_NR_MEMORY_EVENTS,
@@ -66,9 +67,9 @@ __hugetlb_cgroup_from_page(struct page *page, bool rsvd)
 	if (compound_order(page) < HUGETLB_CGROUP_MIN_ORDER)
 		return NULL;
 	if (rsvd)
-		return (struct hugetlb_cgroup *)page[3].private;
+		return (void *)page_private(page + SUBPAGE_INDEX_CGROUP_RSVD);
 	else
-		return (struct hugetlb_cgroup *)page[2].private;
+		return (void *)page_private(page + SUBPAGE_INDEX_CGROUP);
 }
 
 static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
@@ -90,9 +91,11 @@ static inline int __set_hugetlb_cgroup(struct page *page,
 	if (compound_order(page) < HUGETLB_CGROUP_MIN_ORDER)
 		return -1;
 	if (rsvd)
-		page[3].private = (unsigned long)h_cg;
+		set_page_private(page + SUBPAGE_INDEX_CGROUP_RSVD,
+				 (unsigned long)h_cg);
 	else
-		page[2].private = (unsigned long)h_cg;
+		set_page_private(page + SUBPAGE_INDEX_CGROUP,
+				 (unsigned long)h_cg);
 	return 0;
 }
 
-- 
2.11.0


  parent reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-15  8:39 [PATCH v20 0/9] Free some vmemmap pages of HugeTLB page Muchun Song
2021-04-15  8:39 ` [PATCH v20 1/9] mm: memory_hotplug: factor out bootmem core functions to bootmem_info.c Muchun Song
2021-04-15  8:39 ` [PATCH v20 2/9] mm: hugetlb: introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2021-04-15  8:39 ` Muchun Song [this message]
2021-04-16 18:54   ` [PATCH v20 3/9] mm: hugetlb: gather discrete indexes of tail page Mike Kravetz
2021-04-15  8:40 ` [PATCH v20 4/9] mm: hugetlb: free the vmemmap pages associated with each HugeTLB page Muchun Song
2021-04-16 21:10   ` Mike Kravetz
2021-04-17  2:55     ` [External] " Muchun Song
2021-04-15  8:40 ` [PATCH v20 5/9] mm: hugetlb: defer freeing of HugeTLB pages Muchun Song
2021-04-16 23:55   ` Mike Kravetz
2021-04-17  4:13     ` [External] " Muchun Song
2021-04-15  8:40 ` [PATCH v20 6/9] mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page Muchun Song
2021-04-19 23:19   ` Mike Kravetz
2021-04-20  8:46     ` [External] " Muchun Song
2021-04-20 17:48       ` Mike Kravetz
2021-04-21  3:42         ` Muchun Song
2021-04-15  8:40 ` [PATCH v20 7/9] mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap Muchun Song
2021-04-19 23:41   ` Mike Kravetz
2021-04-15  8:40 ` [PATCH v20 8/9] mm: memory_hotplug: disable memmap_on_memory when hugetlb_free_vmemmap enabled Muchun Song
2021-04-20 10:35   ` Oscar Salvador
2021-04-21  3:41     ` [External] " Muchun Song
2021-04-21  7:33       ` Oscar Salvador
2021-04-21  9:06         ` Muchun Song
2021-04-15  8:40 ` [PATCH v20 9/9] mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate Muchun Song

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