[PATCH v3 30/54] selftests/mm: compaction_test: use HugeTLB helpers ...

[Mike Rapoport <rppt@kernel.org>]

From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>

... instead of open coded access of HugeTLB parameters via /proc.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 tools/testing/selftests/mm/compaction_test.c | 113 +++----------------
 1 file changed, 17 insertions(+), 96 deletions(-)

diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c
index 30209c40b697..962a50c3d66f 100644
--- a/tools/testing/selftests/mm/compaction_test.c
+++ b/tools/testing/selftests/mm/compaction_test.c
@@ -17,6 +17,7 @@
 #include <string.h>
 
 #include "kselftest.h"
+#include "hugepage_settings.h"
 
 #define MAP_SIZE_MB	100
 #define MAP_SIZE	(MAP_SIZE_MB * 1024 * 1024)
@@ -82,75 +83,33 @@ int prereq(void)
 	return -1;
 }
 
-int check_compaction(unsigned long mem_free, unsigned long hugepage_size,
-		     unsigned long initial_nr_hugepages)
+int check_compaction(unsigned long mem_free, unsigned long hugepage_size)
 {
-	unsigned long nr_hugepages_ul;
-	int fd, ret = -1;
+	unsigned long nr_hugepages;
 	int compaction_index = 0;
-	char nr_hugepages[20] = {0};
-	char init_nr_hugepages[24] = {0};
-	char target_nr_hugepages[24] = {0};
-	int slen;
-
-	snprintf(init_nr_hugepages, sizeof(init_nr_hugepages),
-		 "%lu", initial_nr_hugepages);
+	int ret = -1;
 
 	/* We want to test with 80% of available memory. Else, OOM killer comes
 	   in to play */
 	mem_free = mem_free * 0.8;
 
-	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
-	if (fd < 0) {
-		ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
-			       strerror(errno));
-		ret = -1;
-		goto out;
-	}
-
 	/*
 	 * Request huge pages for about half of the free memory. The Kernel
 	 * will allocate as much as it can, and we expect it will get at least 1/3
 	 */
-	nr_hugepages_ul = mem_free / hugepage_size / 2;
-	snprintf(target_nr_hugepages, sizeof(target_nr_hugepages),
-		 "%lu", nr_hugepages_ul);
-
-	slen = strlen(target_nr_hugepages);
-	if (write(fd, target_nr_hugepages, slen) != slen) {
-		ksft_print_msg("Failed to write %lu to /proc/sys/vm/nr_hugepages: %s\n",
-			       nr_hugepages_ul, strerror(errno));
-		goto close_fd;
-	}
-
-	lseek(fd, 0, SEEK_SET);
-
-	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
-		ksft_print_msg("Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n",
-			       strerror(errno));
-		goto close_fd;
-	}
+	nr_hugepages = mem_free / hugepage_size / 2;
+	hugetlb_set_nr_default_pages(nr_hugepages);
 
 	/* We should have been able to request at least 1/3 rd of the memory in
 	   huge pages */
-	nr_hugepages_ul = strtoul(nr_hugepages, NULL, 10);
-	if (!nr_hugepages_ul) {
+	nr_hugepages = hugetlb_nr_default_pages();
+	if (!nr_hugepages) {
 		ksft_print_msg("ERROR: No memory is available as huge pages\n");
 		goto close_fd;
 	}
-	compaction_index = mem_free/(nr_hugepages_ul * hugepage_size);
-
-	lseek(fd, 0, SEEK_SET);
-
-	if (write(fd, init_nr_hugepages, strlen(init_nr_hugepages))
-	    != strlen(init_nr_hugepages)) {
-		ksft_print_msg("Failed to write value to /proc/sys/vm/nr_hugepages: %s\n",
-			       strerror(errno));
-		goto close_fd;
-	}
+	compaction_index = mem_free/(nr_hugepages * hugepage_size);
 
-	ksft_print_msg("Number of huge pages allocated = %lu\n",
-		       nr_hugepages_ul);
+	ksft_print_msg("Number of huge pages allocated = %lu\n", nr_hugepages);
 
 	if (compaction_index > 3) {
 		ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
@@ -161,48 +120,10 @@ int check_compaction(unsigned long mem_free, unsigned long hugepage_size,
 	ret = 0;
 
  close_fd:
-	close(fd);
- out:
 	ksft_test_result(ret == 0, "check_compaction\n");
 	return ret;
 }
 
-int set_zero_hugepages(unsigned long *initial_nr_hugepages)
-{
-	int fd, ret = -1;
-	char nr_hugepages[20] = {0};
-
-	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
-	if (fd < 0) {
-		ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
-			       strerror(errno));
-		goto out;
-	}
-	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
-		ksft_print_msg("Failed to read from /proc/sys/vm/nr_hugepages: %s\n",
-			       strerror(errno));
-		goto close_fd;
-	}
-
-	lseek(fd, 0, SEEK_SET);
-
-	/* Start with the initial condition of 0 huge pages */
-	if (write(fd, "0", sizeof(char)) != sizeof(char)) {
-		ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
-			       strerror(errno));
-		goto close_fd;
-	}
-
-	*initial_nr_hugepages = strtoul(nr_hugepages, NULL, 10);
-	ret = 0;
-
- close_fd:
-	close(fd);
-
- out:
-	return ret;
-}
-
 int main(int argc, char **argv)
 {
 	struct rlimit lim;
@@ -212,18 +133,19 @@ int main(int argc, char **argv)
 	unsigned long mem_free = 0;
 	unsigned long hugepage_size = 0;
 	long mem_fragmentable_MB = 0;
-	unsigned long initial_nr_hugepages;
 
 	ksft_print_header();
 
 	if (prereq() || geteuid())
 		ksft_exit_skip("Prerequisites unsatisfied\n");
 
-	ksft_set_plan(1);
-
 	/* Start the test without hugepages reducing mem_free */
-	if (set_zero_hugepages(&initial_nr_hugepages))
-		ksft_exit_fail();
+	hugetlb_save_settings();
+	hugetlb_set_nr_default_pages(0);
+	if (hugetlb_nr_default_pages())
+		ksft_exit_skip("Could not reset nr_hugepages\n");
+
+	ksft_set_plan(1);
 
 	lim.rlim_cur = RLIM_INFINITY;
 	lim.rlim_max = RLIM_INFINITY;
@@ -268,8 +190,7 @@ int main(int argc, char **argv)
 		entry = entry->next;
 	}
 
-	if (check_compaction(mem_free, hugepage_size,
-			     initial_nr_hugepages) == 0)
+	if (check_compaction(mem_free, hugepage_size) == 0)
 		ksft_exit_pass();
 
 	ksft_exit_fail();
-- 
2.53.0