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From: Muchun Song <songmuchun@bytedance.com>
To: mike.kravetz@oracle.com, akpm@linux-foundation.org,
	osalvador@suse.de, mhocko@suse.com, song.bao.hua@hisilicon.com,
	david@redhat.com, chenhuang5@huawei.com, bodeddub@amazon.com,
	corbet@lwn.net, willy@infradead.org
Cc: duanxiongchun@bytedance.com, fam.zheng@bytedance.com,
	smuchun@gmail.com, zhengqi.arch@bytedance.com,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Muchun Song <songmuchun@bytedance.com>
Subject: [PATCH RESEND v2 4/4] selftests: vm: add a hugetlb test case
Date: Fri, 17 Sep 2021 11:48:15 +0800	[thread overview]
Message-ID: <20210917034815.80264-5-songmuchun@bytedance.com> (raw)
In-Reply-To: <20210917034815.80264-1-songmuchun@bytedance.com>

Since the head vmemmap page frame associated with each HugeTLB page is
reused, we should hide the PG_head flag of tail struct page from the
user. Add a tese case to check whether it is work properly.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 tools/testing/selftests/vm/vmemmap_hugetlb.c | 139 +++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 tools/testing/selftests/vm/vmemmap_hugetlb.c

diff --git a/tools/testing/selftests/vm/vmemmap_hugetlb.c b/tools/testing/selftests/vm/vmemmap_hugetlb.c
new file mode 100644
index 000000000000..b6e945bf4053
--- /dev/null
+++ b/tools/testing/selftests/vm/vmemmap_hugetlb.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * A test case of using hugepage memory in a user application using the
+ * mmap system call with MAP_HUGETLB flag.  Before running this program
+ * make sure the administrator has allocated enough default sized huge
+ * pages to cover the 2 MB allocation.
+ *
+ * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages.
+ * That means the addresses starting with 0x800000... will need to be
+ * specified.  Specifying a fixed address is not required on ppc64, i386
+ * or x86_64.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+
+#define MAP_LENGTH		(2UL * 1024 * 1024)
+
+#ifndef MAP_HUGETLB
+#define MAP_HUGETLB		0x40000	/* arch specific */
+#endif
+
+#define PAGE_SIZE		4096
+
+#define PAGE_COMPOUND_HEAD	(1UL << 15)
+#define PAGE_COMPOUND_TAIL	(1UL << 16)
+#define PAGE_HUGE		(1UL << 17)
+
+#define HEAD_PAGE_FLAGS		(PAGE_COMPOUND_HEAD | PAGE_HUGE)
+#define TAIL_PAGE_FLAGS		(PAGE_COMPOUND_TAIL | PAGE_HUGE)
+
+#define PM_PFRAME_BITS		55
+#define PM_PFRAME_MASK		~((1UL << PM_PFRAME_BITS) - 1)
+
+/* Only ia64 requires this */
+#ifdef __ia64__
+#define MAP_ADDR		(void *)(0x8000000000000000UL)
+#define MAP_FLAGS		(MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED)
+#else
+#define MAP_ADDR		NULL
+#define MAP_FLAGS		(MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
+#endif
+
+static void write_bytes(char *addr, size_t length)
+{
+	unsigned long i;
+
+	for (i = 0; i < length; i++)
+		*(addr + i) = (char)i;
+}
+
+static unsigned long virt_to_pfn(void *addr)
+{
+	int fd;
+	unsigned long pagemap;
+
+	fd = open("/proc/self/pagemap", O_RDONLY);
+	if (fd < 0)
+		return -1UL;
+
+	lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET);
+	read(fd, &pagemap, sizeof(pagemap));
+	close(fd);
+
+	return pagemap & ~PM_PFRAME_MASK;
+}
+
+static int check_page_flags(unsigned long pfn)
+{
+	int fd, i;
+	unsigned long pageflags;
+
+	fd = open("/proc/kpageflags", O_RDONLY);
+	if (fd < 0)
+		return -1;
+
+	lseek(fd, pfn * sizeof(pageflags), SEEK_SET);
+
+	read(fd, &pageflags, sizeof(pageflags));
+	if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) {
+		close(fd);
+		printf("Head page flags (%lx) is invalid\n", pageflags);
+		return -1;
+	}
+
+	for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) {
+		read(fd, &pageflags, sizeof(pageflags));
+		if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS ||
+		    (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) {
+			close(fd);
+			printf("Tail page flags (%lx) is invalid\n", pageflags);
+			return -1;
+		}
+	}
+
+	close(fd);
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	void *addr;
+	unsigned long pfn;
+
+	addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+
+	/* Trigger allocation of HugeTLB page. */
+	write_bytes(addr, MAP_LENGTH);
+
+	pfn = virt_to_pfn(addr);
+	if (pfn == -1UL) {
+		munmap(addr, MAP_LENGTH);
+		perror("virt_to_pfn");
+		exit(1);
+	}
+
+	printf("Returned address is %p whose pfn is %lx\n", addr, pfn);
+
+	if (check_page_flags(pfn) < 0) {
+		munmap(addr, MAP_LENGTH);
+		perror("check_page_flags");
+		exit(1);
+	}
+
+	/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
+	if (munmap(addr, MAP_LENGTH)) {
+		perror("munmap");
+		exit(1);
+	}
+
+	return 0;
+}
-- 
2.11.0



  parent reply	other threads:[~2021-09-17  3:53 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-17  3:48 [PATCH RESEND v2 0/4] Free the 2nd vmemmap page associated with each HugeTLB page Muchun Song
2021-09-17  3:48 ` [PATCH RESEND v2 1/4] mm: hugetlb: free " Muchun Song
2021-09-18  4:38   ` Barry Song
2021-09-18 10:06     ` Muchun Song
2021-09-21  6:43       ` Muchun Song
2021-09-21 10:22       ` Muchun Song
2021-09-21  0:11         ` Barry Song
2021-09-21 13:46           ` Muchun Song
2021-09-21 20:43             ` Barry Song
2021-09-22  2:38               ` Muchun Song
2021-09-22  7:36                 ` Barry Song
2021-09-17  3:48 ` [PATCH RESEND v2 2/4] mm: hugetlb: replace hugetlb_free_vmemmap_enabled with a static_key Muchun Song
2021-09-18  4:55   ` Barry Song
2021-09-18 10:30     ` Muchun Song
2021-09-18 11:14       ` Barry Song
2021-09-18 11:47         ` Muchun Song
2021-09-18 12:27           ` Barry Song
2021-09-17  3:48 ` [PATCH RESEND v2 3/4] mm: sparsemem: use page table lock to protect kernel pmd operations Muchun Song
2021-09-18  5:06   ` Barry Song
2021-09-18 10:51     ` Muchun Song
2021-09-18 11:01       ` Barry Song
2021-09-17  3:48 ` Muchun Song [this message]
2021-09-18  5:20   ` [PATCH RESEND v2 4/4] selftests: vm: add a hugetlb test case Barry Song
2021-09-20 14:26     ` Muchun Song
2021-09-21  0:28       ` Barry Song
2021-09-21 13:18         ` Muchun Song

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