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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,
	mchehab+huawei@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
Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	Muchun Song <songmuchun@bytedance.com>
Subject: [RFC PATCH 13/24] mm/hugetlb: Allocate the vmemmap pages associated with each hugetlb page
Date: Tue, 15 Sep 2020 20:59:36 +0800	[thread overview]
Message-ID: <20200915125947.26204-14-songmuchun@bytedance.com> (raw)
In-Reply-To: <20200915125947.26204-1-songmuchun@bytedance.com>

When we free a hugetlb page to the buddy, we should allocate the vmemmap
pages associated with it. We can do that in the __free_hugepage().

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/hugetlb.c | 108 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 6b57a1183785..d0f09fe531fc 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1299,6 +1299,7 @@ static void __free_hugepage(struct hstate *h, struct page *page);
 
 #define RESERVE_VMEMMAP_NR	2U
 #define RESERVE_VMEMMAP_SIZE	(RESERVE_VMEMMAP_NR << PAGE_SHIFT)
+#define GFP_VMEMMAP_PAGE	(GFP_KERNEL | __GFP_NOFAIL | __GFP_MEMALLOC)
 
 #define page_huge_pte(page)	((page)->pmd_huge_pte)
 
@@ -1645,6 +1646,107 @@ static void free_huge_page_vmemmap(struct hstate *h, struct page *head)
 	free_vmemmap_page_list(&free_pages);
 }
 
+static void __remap_huge_page_pte_vmemmap(struct page *reuse, pte_t *ptep,
+					  unsigned long start,
+					  unsigned int nr_remap,
+					  struct list_head *remap_pages)
+{
+	void *from = (void *)page_private(reuse);
+	unsigned long addr, end = start + (nr_remap << PAGE_SHIFT);
+
+	for (addr = start; addr < end; addr += PAGE_SIZE) {
+		void *to;
+		struct page *page;
+		pte_t entry, old = *ptep;
+
+		page = list_first_entry_or_null(remap_pages, struct page, lru);
+		list_del(&page->lru);
+		to = page_to_virt(page);
+		copy_page(to, from);
+
+		/*
+		 * Make sure that any data that writes to the @to is made
+		 * visible to the physical page.
+		 */
+		flush_kernel_vmap_range(to, PAGE_SIZE);
+
+		prepare_vmemmap_page(page);
+
+		entry = mk_pte(page, PAGE_KERNEL);
+		set_pte_at(&init_mm, addr, ptep++, entry);
+
+		VM_BUG_ON(!pte_present(old) || pte_page(old) != reuse);
+	}
+}
+
+static void __remap_huge_page_pmd_vmemmap(struct hstate *h, pmd_t *pmd,
+					  unsigned long addr,
+					  struct list_head *remap_pages)
+{
+	unsigned long next;
+	unsigned long start = addr + RESERVE_VMEMMAP_NR * PAGE_SIZE;
+	unsigned long end = addr + nr_vmemmap_size(h);
+	struct page *reuse = NULL;
+
+	addr = start;
+	do {
+		unsigned int nr_pages;
+		pte_t *ptep;
+
+		ptep = pte_offset_kernel(pmd, addr);
+		if (!reuse) {
+			reuse = pte_page(ptep[-1]);
+			set_page_private(reuse, addr - PAGE_SIZE);
+		}
+
+		next = vmemmap_hpage_addr_end(addr, end);
+		nr_pages = (next - addr) >> PAGE_SHIFT;
+		__remap_huge_page_pte_vmemmap(reuse, ptep, addr, nr_pages,
+					      remap_pages);
+	} while (pmd++, addr = next, addr != end);
+
+	flush_tlb_kernel_range(start, end);
+}
+
+static inline void alloc_vmemmap_pages(struct hstate *h, struct list_head *list)
+{
+	int i;
+
+	for (i = 0; i < nr_free_vmemmap(h); i++) {
+		struct page *page;
+
+		/* This should not fail */
+		page = alloc_page(GFP_VMEMMAP_PAGE);
+		list_add_tail(&page->lru, list);
+	}
+}
+
+static void alloc_huge_page_vmemmap(struct hstate *h, struct page *head)
+{
+	pmd_t *pmd;
+	spinlock_t *ptl;
+	LIST_HEAD(remap_pages);
+
+	if (!nr_free_vmemmap(h))
+		return;
+
+	alloc_vmemmap_pages(h, &remap_pages);
+
+	pmd = vmemmap_to_pmd(head);
+	ptl = vmemmap_pmd_lockptr(pmd);
+
+	spin_lock(ptl);
+	__remap_huge_page_pmd_vmemmap(h, pmd, (unsigned long)head,
+				      &remap_pages);
+	if (!freed_vmemmap_hpage_dec(pmd_page(*pmd))) {
+		/*
+		 * Todo:
+		 * Merge pte to huge pmd if it has ever been split.
+		 */
+	}
+	spin_unlock(ptl);
+}
+
 /*
  * As update_and_free_page() is be called from a non-task context(and hold
  * hugetlb_lock), we can defer the actual freeing in a workqueue to prevent
@@ -1720,6 +1822,10 @@ static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head)
 {
 }
 
+static inline void alloc_huge_page_vmemmap(struct hstate *h, struct page *head)
+{
+}
+
 static inline void __update_and_free_page(struct hstate *h, struct page *page)
 {
 	__free_hugepage(h, page);
@@ -1752,6 +1858,8 @@ static void __free_hugepage(struct hstate *h, struct page *page)
 {
 	int i;
 
+	alloc_huge_page_vmemmap(h, page);
+
 	for (i = 0; i < pages_per_huge_page(h); i++) {
 		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
 				1 << PG_referenced | 1 << PG_dirty |
-- 
2.20.1


  parent reply	other threads:[~2020-09-15 13:03 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15 12:59 [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap pages of " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 01/24] mm/memory_hotplug: Move bootmem info registration API to bootmem_info.c Muchun Song
2020-09-29 22:46   ` Mike Kravetz
2020-09-15 12:59 ` [RFC PATCH 02/24] mm/memory_hotplug: Move {get,put}_page_bootmem() " Muchun Song
2020-09-29 23:30   ` Mike Kravetz
2020-09-15 12:59 ` [RFC PATCH 03/24] mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2020-09-16  2:13   ` Randy Dunlap
2020-09-29 23:41   ` Mike Kravetz
2020-09-30  2:56     ` [External] " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 04/24] mm/hugetlb: Register bootmem info when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2020-09-15 12:59 ` [RFC PATCH 05/24] mm/hugetlb: Introduce nr_free_vmemmap_pages in the struct hstate Muchun Song
2020-09-30 22:41   ` Mike Kravetz
2020-10-01  2:57     ` [External] " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 06/24] mm/hugetlb: Introduce pgtable allocation/freeing helpers Muchun Song
2020-09-15 12:59 ` [RFC PATCH 07/24] mm/hugetlb: Add freeing unused vmemmap pages support for x86 Muchun Song
2020-09-15 12:59 ` [RFC PATCH 08/24] mm/bootmem_info: Introduce {free,prepare}_vmemmap_page() Muchun Song
2020-09-15 12:59 ` [RFC PATCH 09/24] x86/mm: Introduce VMEMMAP_SIZE/VMEMMAP_END macro Muchun Song
2020-09-15 12:59 ` [RFC PATCH 10/24] mm/hugetlb: Free the vmemmap pages associated with each hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 11/24] mm/hugetlb: Add vmemmap_pmd_huge macro for x86 Muchun Song
2020-09-15 12:59 ` [RFC PATCH 12/24] mm/hugetlb: Defer freeing of hugetlb pages Muchun Song
2020-09-15 12:59 ` Muchun Song [this message]
2020-09-15 12:59 ` [RFC PATCH 14/24] mm/hugetlb: Introduce remap_huge_page_pmd_vmemmap helper Muchun Song
2020-09-15 12:59 ` [RFC PATCH 15/24] mm/hugetlb: Use PG_slab to indicate split pmd Muchun Song
2020-09-15 12:59 ` [RFC PATCH 16/24] mm/hugetlb: Support freeing vmemmap pages of gigantic page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 17/24] mm/hugetlb: Add a BUILD_BUG_ON to check if struct page size is a power of two Muchun Song
2020-09-15 12:59 ` [RFC PATCH 18/24] mm/hugetlb: Clear PageHWPoison on the non-error memory page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 19/24] mm/hugetlb: Flush work when dissolving hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 20/24] mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap Muchun Song
2020-09-16  2:10   ` Randy Dunlap
2020-09-16  2:50     ` [External] " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 21/24] mm/hugetlb: Merge pte to huge pmd only for gigantic page Muchun Song
2020-09-20  9:59   ` Muchun Song
2020-09-15 12:59 ` [RFC PATCH 22/24] mm/hugetlb: Implement vmemmap_pmd_mkhuge macro Muchun Song
2020-09-15 12:59 ` [RFC PATCH 23/24] mm/hugetlb: Gather discrete indexes of tail page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 24/24] mm/hugetlb: Add BUILD_BUG_ON to catch invalid usage of tail struct page Muchun Song
2020-09-15 14:32 ` [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap pages of hugetlb page Matthew Wilcox
2020-09-15 14:53   ` Dave Hansen
2020-09-15 15:28   ` [External] " Muchun Song
2020-09-15 15:42     ` Matthew Wilcox
2020-09-15 17:32       ` Muchun Song
2020-09-15 17:39         ` Matthew Wilcox
2020-09-15 18:03           ` Muchun Song
2020-09-15 18:15             ` Matthew Wilcox
2020-09-16  2:45               ` Muchun Song
2020-09-29 21:58 ` Mike Kravetz
2020-09-30  3:13   ` Matthew Wilcox
2020-10-07 21:12   ` Mike Kravetz
2020-10-09  4:13     ` [External] " Muchun Song

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