1 files changed, 0 insertions, 1320 deletions
diff --git a/tools/testing/selftests/mm/guard-pages.c b/tools/testing/selftests/mm/guard-pages.c
deleted file mode 100644
index ece37212a8a2..000000000000
--- a/tools/testing/selftests/mm/guard-pages.c
+++ /dev/null
@@ -1,1320 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-#define _GNU_SOURCE
-#include "../kselftest_harness.h"
-#include <asm-generic/mman.h> /* Force the import of the tools version. */
-#include <assert.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <linux/userfaultfd.h>
-#include <setjmp.h>
-#include <signal.h>
-#include <stdbool.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/ioctl.h>
-#include <sys/mman.h>
-#include <sys/syscall.h>
-#include <sys/uio.h>
-#include <unistd.h>
-
-/*
- * Ignore the checkpatch warning, as per the C99 standard, section 7.14.1.1:
- *
- * "If the signal occurs other than as the result of calling the abort or raise
- *  function, the behavior is undefined if the signal handler refers to any
- *  object with static storage duration other than by assigning a value to an
- *  object declared as volatile sig_atomic_t"
- */
-static volatile sig_atomic_t signal_jump_set;
-static sigjmp_buf signal_jmp_buf;
-
-/*
- * Ignore the checkpatch warning, we must read from x but don't want to do
- * anything with it in order to trigger a read page fault. We therefore must use
- * volatile to stop the compiler from optimising this away.
- */
-#define FORCE_READ(x) (*(volatile typeof(x) *)x)
-
-static int userfaultfd(int flags)
-{
-	return syscall(SYS_userfaultfd, flags);
-}
-
-static void handle_fatal(int c)
-{
-	if (!signal_jump_set)
-		return;
-
-	siglongjmp(signal_jmp_buf, c);
-}
-
-static int pidfd_open(pid_t pid, unsigned int flags)
-{
-	return syscall(SYS_pidfd_open, pid, flags);
-}
-
-static ssize_t sys_process_madvise(int pidfd, const struct iovec *iovec,
-				   size_t n, int advice, unsigned int flags)
-{
-	return syscall(__NR_process_madvise, pidfd, iovec, n, advice, flags);
-}
-
-/*
- * Enable our signal catcher and try to read/write the specified buffer. The
- * return value indicates whether the read/write succeeds without a fatal
- * signal.
- */
-static bool try_access_buf(char *ptr, bool write)
-{
-	bool failed;
-
-	/* Tell signal handler to jump back here on fatal signal. */
-	signal_jump_set = true;
-	/* If a fatal signal arose, we will jump back here and failed is set. */
-	failed = sigsetjmp(signal_jmp_buf, 0) != 0;
-
-	if (!failed) {
-		if (write)
-			*ptr = 'x';
-		else
-			FORCE_READ(ptr);
-	}
-
-	signal_jump_set = false;
-	return !failed;
-}
-
-/* Try and read from a buffer, return true if no fatal signal. */
-static bool try_read_buf(char *ptr)
-{
-	return try_access_buf(ptr, false);
-}
-
-/* Try and write to a buffer, return true if no fatal signal. */
-static bool try_write_buf(char *ptr)
-{
-	return try_access_buf(ptr, true);
-}
-
-/*
- * Try and BOTH read from AND write to a buffer, return true if BOTH operations
- * succeed.
- */
-static bool try_read_write_buf(char *ptr)
-{
-	return try_read_buf(ptr) && try_write_buf(ptr);
-}
-
-FIXTURE(guard_pages)
-{
-	unsigned long page_size;
-};
-
-FIXTURE_SETUP(guard_pages)
-{
-	struct sigaction act = {
-		.sa_handler = &handle_fatal,
-		.sa_flags = SA_NODEFER,
-	};
-
-	sigemptyset(&act.sa_mask);
-	if (sigaction(SIGSEGV, &act, NULL))
-		ksft_exit_fail_perror("sigaction");
-
-	self->page_size = (unsigned long)sysconf(_SC_PAGESIZE);
-};
-
-FIXTURE_TEARDOWN(guard_pages)
-{
-	struct sigaction act = {
-		.sa_handler = SIG_DFL,
-		.sa_flags = SA_NODEFER,
-	};
-
-	sigemptyset(&act.sa_mask);
-	sigaction(SIGSEGV, &act, NULL);
-}
-
-TEST_F(guard_pages, basic)
-{
-	const unsigned long NUM_PAGES = 10;
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	int i;
-
-	ptr = mmap(NULL, NUM_PAGES * page_size, PROT_READ | PROT_WRITE,
-		   MAP_PRIVATE | MAP_ANON, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Trivially assert we can touch the first page. */
-	ASSERT_TRUE(try_read_write_buf(ptr));
-
-	ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Establish that 1st page SIGSEGV's. */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-
-	/* Ensure we can touch everything else.*/
-	for (i = 1; i < NUM_PAGES; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	/* Establish a guard page at the end of the mapping. */
-	ASSERT_EQ(madvise(&ptr[(NUM_PAGES - 1) * page_size], page_size,
-			  MADV_GUARD_INSTALL), 0);
-
-	/* Check that both guard pages result in SIGSEGV. */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-	ASSERT_FALSE(try_read_write_buf(&ptr[(NUM_PAGES - 1) * page_size]));
-
-	/* Remove the first guard page. */
-	ASSERT_FALSE(madvise(ptr, page_size, MADV_GUARD_REMOVE));
-
-	/* Make sure we can touch it. */
-	ASSERT_TRUE(try_read_write_buf(ptr));
-
-	/* Remove the last guard page. */
-	ASSERT_FALSE(madvise(&ptr[(NUM_PAGES - 1) * page_size], page_size,
-			     MADV_GUARD_REMOVE));
-
-	/* Make sure we can touch it. */
-	ASSERT_TRUE(try_read_write_buf(&ptr[(NUM_PAGES - 1) * page_size]));
-
-	/*
-	 *  Test setting a _range_ of pages, namely the first 3. The first of
-	 *  these be faulted in, so this also tests that we can install guard
-	 *  pages over backed pages.
-	 */
-	ASSERT_EQ(madvise(ptr, 3 * page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Make sure they are all guard pages. */
-	for (i = 0; i < 3; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Make sure the rest are not. */
-	for (i = 3; i < NUM_PAGES; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	/* Remove guard pages. */
-	ASSERT_EQ(madvise(ptr, NUM_PAGES * page_size, MADV_GUARD_REMOVE), 0);
-
-	/* Now make sure we can touch everything. */
-	for (i = 0; i < NUM_PAGES; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	/*
-	 * Now remove all guard pages, make sure we don't remove existing
-	 * entries.
-	 */
-	ASSERT_EQ(madvise(ptr, NUM_PAGES * page_size, MADV_GUARD_REMOVE), 0);
-
-	for (i = 0; i < NUM_PAGES * page_size; i += page_size) {
-		char chr = ptr[i];
-
-		ASSERT_EQ(chr, 'x');
-	}
-
-	ASSERT_EQ(munmap(ptr, NUM_PAGES * page_size), 0);
-}
-
-/* Assert that operations applied across multiple VMAs work as expected. */
-TEST_F(guard_pages, multi_vma)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr_region, *ptr, *ptr1, *ptr2, *ptr3;
-	int i;
-
-	/* Reserve a 100 page region over which we can install VMAs. */
-	ptr_region = mmap(NULL, 100 * page_size, PROT_NONE,
-			  MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr_region, MAP_FAILED);
-
-	/* Place a VMA of 10 pages size at the start of the region. */
-	ptr1 = mmap(ptr_region, 10 * page_size, PROT_READ | PROT_WRITE,
-		    MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr1, MAP_FAILED);
-
-	/* Place a VMA of 5 pages size 50 pages into the region. */
-	ptr2 = mmap(&ptr_region[50 * page_size], 5 * page_size,
-		    PROT_READ | PROT_WRITE,
-		    MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr2, MAP_FAILED);
-
-	/* Place a VMA of 20 pages size at the end of the region. */
-	ptr3 = mmap(&ptr_region[80 * page_size], 20 * page_size,
-		    PROT_READ | PROT_WRITE,
-		    MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr3, MAP_FAILED);
-
-	/* Unmap gaps. */
-	ASSERT_EQ(munmap(&ptr_region[10 * page_size], 40 * page_size), 0);
-	ASSERT_EQ(munmap(&ptr_region[55 * page_size], 25 * page_size), 0);
-
-	/*
-	 * We end up with VMAs like this:
-	 *
-	 * 0    10 .. 50   55 .. 80   100
-	 * [---]      [---]      [---]
-	 */
-
-	/*
-	 * Now mark the whole range as guard pages and make sure all VMAs are as
-	 * such.
-	 */
-
-	/*
-	 * madvise() is certifiable and lets you perform operations over gaps,
-	 * everything works, but it indicates an error and errno is set to
-	 * -ENOMEM. Also if anything runs out of memory it is set to
-	 * -ENOMEM. You are meant to guess which is which.
-	 */
-	ASSERT_EQ(madvise(ptr_region, 100 * page_size, MADV_GUARD_INSTALL), -1);
-	ASSERT_EQ(errno, ENOMEM);
-
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr1[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	for (i = 0; i < 5; i++) {
-		char *curr = &ptr2[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	for (i = 0; i < 20; i++) {
-		char *curr = &ptr3[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Now remove guar pages over range and assert the opposite. */
-
-	ASSERT_EQ(madvise(ptr_region, 100 * page_size, MADV_GUARD_REMOVE), -1);
-	ASSERT_EQ(errno, ENOMEM);
-
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr1[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	for (i = 0; i < 5; i++) {
-		char *curr = &ptr2[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	for (i = 0; i < 20; i++) {
-		char *curr = &ptr3[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	/* Now map incompatible VMAs in the gaps. */
-	ptr = mmap(&ptr_region[10 * page_size], 40 * page_size,
-		   PROT_READ | PROT_WRITE | PROT_EXEC,
-		   MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-	ptr = mmap(&ptr_region[55 * page_size], 25 * page_size,
-		   PROT_READ | PROT_WRITE | PROT_EXEC,
-		   MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/*
-	 * We end up with VMAs like this:
-	 *
-	 * 0    10 .. 50   55 .. 80   100
-	 * [---][xxxx][---][xxxx][---]
-	 *
-	 * Where 'x' signifies VMAs that cannot be merged with those adjacent to
-	 * them.
-	 */
-
-	/* Multiple VMAs adjacent to one another should result in no error. */
-	ASSERT_EQ(madvise(ptr_region, 100 * page_size, MADV_GUARD_INSTALL), 0);
-	for (i = 0; i < 100; i++) {
-		char *curr = &ptr_region[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-	ASSERT_EQ(madvise(ptr_region, 100 * page_size, MADV_GUARD_REMOVE), 0);
-	for (i = 0; i < 100; i++) {
-		char *curr = &ptr_region[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr_region, 100 * page_size), 0);
-}
-
-/*
- * Assert that batched operations performed using process_madvise() work as
- * expected.
- */
-TEST_F(guard_pages, process_madvise)
-{
-	const unsigned long page_size = self->page_size;
-	pid_t pid = getpid();
-	int pidfd = pidfd_open(pid, 0);
-	char *ptr_region, *ptr1, *ptr2, *ptr3;
-	ssize_t count;
-	struct iovec vec[6];
-
-	ASSERT_NE(pidfd, -1);
-
-	/* Reserve region to map over. */
-	ptr_region = mmap(NULL, 100 * page_size, PROT_NONE,
-			  MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr_region, MAP_FAILED);
-
-	/*
-	 * 10 pages offset 1 page into reserve region. We MAP_POPULATE so we
-	 * overwrite existing entries and test this code path against
-	 * overwriting existing entries.
-	 */
-	ptr1 = mmap(&ptr_region[page_size], 10 * page_size,
-		    PROT_READ | PROT_WRITE,
-		    MAP_FIXED | MAP_ANON | MAP_PRIVATE | MAP_POPULATE, -1, 0);
-	ASSERT_NE(ptr1, MAP_FAILED);
-	/* We want guard markers at start/end of each VMA. */
-	vec[0].iov_base = ptr1;
-	vec[0].iov_len = page_size;
-	vec[1].iov_base = &ptr1[9 * page_size];
-	vec[1].iov_len = page_size;
-
-	/* 5 pages offset 50 pages into reserve region. */
-	ptr2 = mmap(&ptr_region[50 * page_size], 5 * page_size,
-		    PROT_READ | PROT_WRITE,
-		    MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr2, MAP_FAILED);
-	vec[2].iov_base = ptr2;
-	vec[2].iov_len = page_size;
-	vec[3].iov_base = &ptr2[4 * page_size];
-	vec[3].iov_len = page_size;
-
-	/* 20 pages offset 79 pages into reserve region. */
-	ptr3 = mmap(&ptr_region[79 * page_size], 20 * page_size,
-		    PROT_READ | PROT_WRITE,
-		    MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr3, MAP_FAILED);
-	vec[4].iov_base = ptr3;
-	vec[4].iov_len = page_size;
-	vec[5].iov_base = &ptr3[19 * page_size];
-	vec[5].iov_len = page_size;
-
-	/* Free surrounding VMAs. */
-	ASSERT_EQ(munmap(ptr_region, page_size), 0);
-	ASSERT_EQ(munmap(&ptr_region[11 * page_size], 39 * page_size), 0);
-	ASSERT_EQ(munmap(&ptr_region[55 * page_size], 24 * page_size), 0);
-	ASSERT_EQ(munmap(&ptr_region[99 * page_size], page_size), 0);
-
-	/* Now guard in one step. */
-	count = sys_process_madvise(pidfd, vec, 6, MADV_GUARD_INSTALL, 0);
-
-	/* OK we don't have permission to do this, skip. */
-	if (count == -1 && errno == EPERM)
-		ksft_exit_skip("No process_madvise() permissions, try running as root.\n");
-
-	/* Returns the number of bytes advised. */
-	ASSERT_EQ(count, 6 * page_size);
-
-	/* Now make sure the guarding was applied. */
-
-	ASSERT_FALSE(try_read_write_buf(ptr1));
-	ASSERT_FALSE(try_read_write_buf(&ptr1[9 * page_size]));
-
-	ASSERT_FALSE(try_read_write_buf(ptr2));
-	ASSERT_FALSE(try_read_write_buf(&ptr2[4 * page_size]));
-
-	ASSERT_FALSE(try_read_write_buf(ptr3));
-	ASSERT_FALSE(try_read_write_buf(&ptr3[19 * page_size]));
-
-	/* Now do the same with unguard... */
-	count = sys_process_madvise(pidfd, vec, 6, MADV_GUARD_REMOVE, 0);
-
-	/* ...and everything should now succeed. */
-
-	ASSERT_TRUE(try_read_write_buf(ptr1));
-	ASSERT_TRUE(try_read_write_buf(&ptr1[9 * page_size]));
-
-	ASSERT_TRUE(try_read_write_buf(ptr2));
-	ASSERT_TRUE(try_read_write_buf(&ptr2[4 * page_size]));
-
-	ASSERT_TRUE(try_read_write_buf(ptr3));
-	ASSERT_TRUE(try_read_write_buf(&ptr3[19 * page_size]));
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr1, 10 * page_size), 0);
-	ASSERT_EQ(munmap(ptr2, 5 * page_size), 0);
-	ASSERT_EQ(munmap(ptr3, 20 * page_size), 0);
-	close(pidfd);
-}
-
-/* Assert that unmapping ranges does not leave guard markers behind. */
-TEST_F(guard_pages, munmap)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr, *ptr_new1, *ptr_new2;
-
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Guard first and last pages. */
-	ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
-	ASSERT_EQ(madvise(&ptr[9 * page_size], page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Assert that they are guarded. */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-	ASSERT_FALSE(try_read_write_buf(&ptr[9 * page_size]));
-
-	/* Unmap them. */
-	ASSERT_EQ(munmap(ptr, page_size), 0);
-	ASSERT_EQ(munmap(&ptr[9 * page_size], page_size), 0);
-
-	/* Map over them.*/
-	ptr_new1 = mmap(ptr, page_size, PROT_READ | PROT_WRITE,
-			MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr_new1, MAP_FAILED);
-	ptr_new2 = mmap(&ptr[9 * page_size], page_size, PROT_READ | PROT_WRITE,
-			MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr_new2, MAP_FAILED);
-
-	/* Assert that they are now not guarded. */
-	ASSERT_TRUE(try_read_write_buf(ptr_new1));
-	ASSERT_TRUE(try_read_write_buf(ptr_new2));
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/* Assert that mprotect() operations have no bearing on guard markers. */
-TEST_F(guard_pages, mprotect)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	int i;
-
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Guard the middle of the range. */
-	ASSERT_EQ(madvise(&ptr[5 * page_size], 2 * page_size,
-			  MADV_GUARD_INSTALL), 0);
-
-	/* Assert that it is indeed guarded. */
-	ASSERT_FALSE(try_read_write_buf(&ptr[5 * page_size]));
-	ASSERT_FALSE(try_read_write_buf(&ptr[6 * page_size]));
-
-	/* Now make these pages read-only. */
-	ASSERT_EQ(mprotect(&ptr[5 * page_size], 2 * page_size, PROT_READ), 0);
-
-	/* Make sure the range is still guarded. */
-	ASSERT_FALSE(try_read_buf(&ptr[5 * page_size]));
-	ASSERT_FALSE(try_read_buf(&ptr[6 * page_size]));
-
-	/* Make sure we can guard again without issue.*/
-	ASSERT_EQ(madvise(&ptr[5 * page_size], 2 * page_size,
-			  MADV_GUARD_INSTALL), 0);
-
-	/* Make sure the range is, yet again, still guarded. */
-	ASSERT_FALSE(try_read_buf(&ptr[5 * page_size]));
-	ASSERT_FALSE(try_read_buf(&ptr[6 * page_size]));
-
-	/* Now unguard the whole range. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
-
-	/* Make sure the whole range is readable. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_TRUE(try_read_buf(curr));
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/* Split and merge VMAs and make sure guard pages still behave. */
-TEST_F(guard_pages, split_merge)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr, *ptr_new;
-	int i;
-
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Guard the whole range. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Make sure the whole range is guarded. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Now unmap some pages in the range so we split. */
-	ASSERT_EQ(munmap(&ptr[2 * page_size], page_size), 0);
-	ASSERT_EQ(munmap(&ptr[5 * page_size], page_size), 0);
-	ASSERT_EQ(munmap(&ptr[8 * page_size], page_size), 0);
-
-	/* Make sure the remaining ranges are guarded post-split. */
-	for (i = 0; i < 2; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-	for (i = 2; i < 5; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-	for (i = 6; i < 8; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-	for (i = 9; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Now map them again - the unmap will have cleared the guards. */
-	ptr_new = mmap(&ptr[2 * page_size], page_size, PROT_READ | PROT_WRITE,
-		       MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr_new, MAP_FAILED);
-	ptr_new = mmap(&ptr[5 * page_size], page_size, PROT_READ | PROT_WRITE,
-		       MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr_new, MAP_FAILED);
-	ptr_new = mmap(&ptr[8 * page_size], page_size, PROT_READ | PROT_WRITE,
-		       MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr_new, MAP_FAILED);
-
-	/* Now make sure guard pages are established. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-		bool result = try_read_write_buf(curr);
-		bool expect_true = i == 2 || i == 5 || i == 8;
-
-		ASSERT_TRUE(expect_true ? result : !result);
-	}
-
-	/* Now guard everything again. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Make sure the whole range is guarded. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Now split the range into three. */
-	ASSERT_EQ(mprotect(ptr, 3 * page_size, PROT_READ), 0);
-	ASSERT_EQ(mprotect(&ptr[7 * page_size], 3 * page_size, PROT_READ), 0);
-
-	/* Make sure the whole range is guarded for read. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_buf(curr));
-	}
-
-	/* Now reset protection bits so we merge the whole thing. */
-	ASSERT_EQ(mprotect(ptr, 3 * page_size, PROT_READ | PROT_WRITE), 0);
-	ASSERT_EQ(mprotect(&ptr[7 * page_size], 3 * page_size,
-			   PROT_READ | PROT_WRITE), 0);
-
-	/* Make sure the whole range is still guarded. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Split range into 3 again... */
-	ASSERT_EQ(mprotect(ptr, 3 * page_size, PROT_READ), 0);
-	ASSERT_EQ(mprotect(&ptr[7 * page_size], 3 * page_size, PROT_READ), 0);
-
-	/* ...and unguard the whole range. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
-
-	/* Make sure the whole range is remedied for read. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_TRUE(try_read_buf(curr));
-	}
-
-	/* Merge them again. */
-	ASSERT_EQ(mprotect(ptr, 3 * page_size, PROT_READ | PROT_WRITE), 0);
-	ASSERT_EQ(mprotect(&ptr[7 * page_size], 3 * page_size,
-			   PROT_READ | PROT_WRITE), 0);
-
-	/* Now ensure the merged range is remedied for read/write. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/* Assert that MADV_DONTNEED does not remove guard markers. */
-TEST_F(guard_pages, dontneed)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	int i;
-
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Back the whole range. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		*curr = 'y';
-	}
-
-	/* Guard every other page. */
-	for (i = 0; i < 10; i += 2) {
-		char *curr = &ptr[i * page_size];
-		int res = madvise(curr, page_size, MADV_GUARD_INSTALL);
-
-		ASSERT_EQ(res, 0);
-	}
-
-	/* Indicate that we don't need any of the range. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_DONTNEED), 0);
-
-	/* Check to ensure guard markers are still in place. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-		bool result = try_read_buf(curr);
-
-		if (i % 2 == 0) {
-			ASSERT_FALSE(result);
-		} else {
-			ASSERT_TRUE(result);
-			/* Make sure we really did get reset to zero page. */
-			ASSERT_EQ(*curr, '\0');
-		}
-
-		/* Now write... */
-		result = try_write_buf(&ptr[i * page_size]);
-
-		/* ...and make sure same result. */
-		ASSERT_TRUE(i % 2 != 0 ? result : !result);
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/* Assert that mlock()'ed pages work correctly with guard markers. */
-TEST_F(guard_pages, mlock)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	int i;
-
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Populate. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		*curr = 'y';
-	}
-
-	/* Lock. */
-	ASSERT_EQ(mlock(ptr, 10 * page_size), 0);
-
-	/* Now try to guard, should fail with EINVAL. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), -1);
-	ASSERT_EQ(errno, EINVAL);
-
-	/* OK unlock. */
-	ASSERT_EQ(munlock(ptr, 10 * page_size), 0);
-
-	/* Guard first half of range, should now succeed. */
-	ASSERT_EQ(madvise(ptr, 5 * page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Make sure guard works. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-		bool result = try_read_write_buf(curr);
-
-		if (i < 5) {
-			ASSERT_FALSE(result);
-		} else {
-			ASSERT_TRUE(result);
-			ASSERT_EQ(*curr, 'x');
-		}
-	}
-
-	/*
-	 * Now lock the latter part of the range. We can't lock the guard pages,
-	 * as this would result in the pages being populated and the guarding
-	 * would cause this to error out.
-	 */
-	ASSERT_EQ(mlock(&ptr[5 * page_size], 5 * page_size), 0);
-
-	/*
-	 * Now remove guard pages, we permit mlock()'d ranges to have guard
-	 * pages removed as it is a non-destructive operation.
-	 */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
-
-	/* Now check that no guard pages remain. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/*
- * Assert that moving, extending and shrinking memory via mremap() retains
- * guard markers where possible.
- *
- * - Moving a mapping alone should retain markers as they are.
- */
-TEST_F(guard_pages, mremap_move)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr, *ptr_new;
-
-	/* Map 5 pages. */
-	ptr = mmap(NULL, 5 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Place guard markers at both ends of the 5 page span. */
-	ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
-	ASSERT_EQ(madvise(&ptr[4 * page_size], page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Make sure the guard pages are in effect. */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-	ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
-
-	/* Map a new region we will move this range into. Doing this ensures
-	 * that we have reserved a range to map into.
-	 */
-	ptr_new = mmap(NULL, 5 * page_size, PROT_NONE, MAP_ANON | MAP_PRIVATE,
-		       -1, 0);
-	ASSERT_NE(ptr_new, MAP_FAILED);
-
-	ASSERT_EQ(mremap(ptr, 5 * page_size, 5 * page_size,
-			 MREMAP_MAYMOVE | MREMAP_FIXED, ptr_new), ptr_new);
-
-	/* Make sure the guard markers are retained. */
-	ASSERT_FALSE(try_read_write_buf(ptr_new));
-	ASSERT_FALSE(try_read_write_buf(&ptr_new[4 * page_size]));
-
-	/*
-	 * Clean up - we only need reference the new pointer as we overwrote the
-	 * PROT_NONE range and moved the existing one.
-	 */
-	munmap(ptr_new, 5 * page_size);
-}
-
-/*
- * Assert that moving, extending and shrinking memory via mremap() retains
- * guard markers where possible.
- *
- * Expanding should retain guard pages, only now in different position. The user
- * will have to remove guard pages manually to fix up (they'd have to do the
- * same if it were a PROT_NONE mapping).
- */
-TEST_F(guard_pages, mremap_expand)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr, *ptr_new;
-
-	/* Map 10 pages... */
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-	/* ...But unmap the last 5 so we can ensure we can expand into them. */
-	ASSERT_EQ(munmap(&ptr[5 * page_size], 5 * page_size), 0);
-
-	/* Place guard markers at both ends of the 5 page span. */
-	ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
-	ASSERT_EQ(madvise(&ptr[4 * page_size], page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Make sure the guarding is in effect. */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-	ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
-
-	/* Now expand to 10 pages. */
-	ptr = mremap(ptr, 5 * page_size, 10 * page_size, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/*
-	 * Make sure the guard markers are retained in their original positions.
-	 */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-	ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
-
-	/* Reserve a region which we can move to and expand into. */
-	ptr_new = mmap(NULL, 20 * page_size, PROT_NONE,
-		       MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr_new, MAP_FAILED);
-
-	/* Now move and expand into it. */
-	ptr = mremap(ptr, 10 * page_size, 20 * page_size,
-		     MREMAP_MAYMOVE | MREMAP_FIXED, ptr_new);
-	ASSERT_EQ(ptr, ptr_new);
-
-	/*
-	 * Again, make sure the guard markers are retained in their original positions.
-	 */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-	ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
-
-	/*
-	 * A real user would have to remove guard markers, but would reasonably
-	 * expect all characteristics of the mapping to be retained, including
-	 * guard markers.
-	 */
-
-	/* Cleanup. */
-	munmap(ptr, 20 * page_size);
-}
-/*
- * Assert that moving, extending and shrinking memory via mremap() retains
- * guard markers where possible.
- *
- * Shrinking will result in markers that are shrunk over being removed. Again,
- * if the user were using a PROT_NONE mapping they'd have to manually fix this
- * up also so this is OK.
- */
-TEST_F(guard_pages, mremap_shrink)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	int i;
-
-	/* Map 5 pages. */
-	ptr = mmap(NULL, 5 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Place guard markers at both ends of the 5 page span. */
-	ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
-	ASSERT_EQ(madvise(&ptr[4 * page_size], page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Make sure the guarding is in effect. */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-	ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
-
-	/* Now shrink to 3 pages. */
-	ptr = mremap(ptr, 5 * page_size, 3 * page_size, MREMAP_MAYMOVE);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* We expect the guard marker at the start to be retained... */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-
-	/* ...But remaining pages will not have guard markers. */
-	for (i = 1; i < 3; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	/*
-	 * As with expansion, a real user would have to remove guard pages and
-	 * fixup. But you'd have to do similar manual things with PROT_NONE
-	 * mappings too.
-	 */
-
-	/*
-	 * If we expand back to the original size, the end marker will, of
-	 * course, no longer be present.
-	 */
-	ptr = mremap(ptr, 3 * page_size, 5 * page_size, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Again, we expect the guard marker at the start to be retained... */
-	ASSERT_FALSE(try_read_write_buf(ptr));
-
-	/* ...But remaining pages will not have guard markers. */
-	for (i = 1; i < 5; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_TRUE(try_read_write_buf(curr));
-	}
-
-	/* Cleanup. */
-	munmap(ptr, 5 * page_size);
-}
-
-/*
- * Assert that forking a process with VMAs that do not have VM_WIPEONFORK set
- * retain guard pages.
- */
-TEST_F(guard_pages, fork)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	pid_t pid;
-	int i;
-
-	/* Map 10 pages. */
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Establish guard pages in the first 5 pages. */
-	ASSERT_EQ(madvise(ptr, 5 * page_size, MADV_GUARD_INSTALL), 0);
-
-	pid = fork();
-	ASSERT_NE(pid, -1);
-	if (!pid) {
-		/* This is the child process now. */
-
-		/* Assert that the guarding is in effect. */
-		for (i = 0; i < 10; i++) {
-			char *curr = &ptr[i * page_size];
-			bool result = try_read_write_buf(curr);
-
-			ASSERT_TRUE(i >= 5 ? result : !result);
-		}
-
-		/* Now unguard the range.*/
-		ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
-
-		exit(0);
-	}
-
-	/* Parent process. */
-
-	/* Parent simply waits on child. */
-	waitpid(pid, NULL, 0);
-
-	/* Child unguard does not impact parent page table state. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-		bool result = try_read_write_buf(curr);
-
-		ASSERT_TRUE(i >= 5 ? result : !result);
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/*
- * Assert expected behaviour after we fork populated ranges of anonymous memory
- * and then guard and unguard the range.
- */
-TEST_F(guard_pages, fork_cow)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	pid_t pid;
-	int i;
-
-	/* Map 10 pages. */
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Populate range. */
-	for (i = 0; i < 10 * page_size; i++) {
-		char chr = 'a' + (i % 26);
-
-		ptr[i] = chr;
-	}
-
-	pid = fork();
-	ASSERT_NE(pid, -1);
-	if (!pid) {
-		/* This is the child process now. */
-
-		/* Ensure the range is as expected. */
-		for (i = 0; i < 10 * page_size; i++) {
-			char expected = 'a' + (i % 26);
-			char actual = ptr[i];
-
-			ASSERT_EQ(actual, expected);
-		}
-
-		/* Establish guard pages across the whole range. */
-		ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
-		/* Remove it. */
-		ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
-
-		/*
-		 * By removing the guard pages, the page tables will be
-		 * cleared. Assert that we are looking at the zero page now.
-		 */
-		for (i = 0; i < 10 * page_size; i++) {
-			char actual = ptr[i];
-
-			ASSERT_EQ(actual, '\0');
-		}
-
-		exit(0);
-	}
-
-	/* Parent process. */
-
-	/* Parent simply waits on child. */
-	waitpid(pid, NULL, 0);
-
-	/* Ensure the range is unchanged in parent anon range. */
-	for (i = 0; i < 10 * page_size; i++) {
-		char expected = 'a' + (i % 26);
-		char actual = ptr[i];
-
-		ASSERT_EQ(actual, expected);
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/*
- * Assert that forking a process with VMAs that do have VM_WIPEONFORK set
- * behave as expected.
- */
-TEST_F(guard_pages, fork_wipeonfork)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	pid_t pid;
-	int i;
-
-	/* Map 10 pages. */
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Mark wipe on fork. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_WIPEONFORK), 0);
-
-	/* Guard the first 5 pages. */
-	ASSERT_EQ(madvise(ptr, 5 * page_size, MADV_GUARD_INSTALL), 0);
-
-	pid = fork();
-	ASSERT_NE(pid, -1);
-	if (!pid) {
-		/* This is the child process now. */
-
-		/* Guard will have been wiped. */
-		for (i = 0; i < 10; i++) {
-			char *curr = &ptr[i * page_size];
-
-			ASSERT_TRUE(try_read_write_buf(curr));
-		}
-
-		exit(0);
-	}
-
-	/* Parent process. */
-
-	waitpid(pid, NULL, 0);
-
-	/* Guard markers should be in effect.*/
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-		bool result = try_read_write_buf(curr);
-
-		ASSERT_TRUE(i >= 5 ? result : !result);
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/* Ensure that MADV_FREE retains guard entries as expected. */
-TEST_F(guard_pages, lazyfree)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	int i;
-
-	/* Map 10 pages. */
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Guard range. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Ensure guarded. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Lazyfree range. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_FREE), 0);
-
-	/* This should leave the guard markers in place. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/* Ensure that MADV_POPULATE_READ, MADV_POPULATE_WRITE behave as expected. */
-TEST_F(guard_pages, populate)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-
-	/* Map 10 pages. */
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Guard range. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Populate read should error out... */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_POPULATE_READ), -1);
-	ASSERT_EQ(errno, EFAULT);
-
-	/* ...as should populate write. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_POPULATE_WRITE), -1);
-	ASSERT_EQ(errno, EFAULT);
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/* Ensure that MADV_COLD, MADV_PAGEOUT do not remove guard markers. */
-TEST_F(guard_pages, cold_pageout)
-{
-	const unsigned long page_size = self->page_size;
-	char *ptr;
-	int i;
-
-	/* Map 10 pages. */
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Guard range. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
-
-	/* Ensured guarded. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Now mark cold. This should have no impact on guard markers. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_COLD), 0);
-
-	/* Should remain guarded. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* OK, now page out. This should equally, have no effect on markers. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_PAGEOUT), 0);
-
-	/* Should remain guarded. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-/* Ensure that guard pages do not break userfaultd. */
-TEST_F(guard_pages, uffd)
-{
-	const unsigned long page_size = self->page_size;
-	int uffd;
-	char *ptr;
-	int i;
-	struct uffdio_api api = {
-		.api = UFFD_API,
-		.features = 0,
-	};
-	struct uffdio_register reg;
-	struct uffdio_range range;
-
-	/* Set up uffd. */
-	uffd = userfaultfd(0);
-	if (uffd == -1 && errno == EPERM)
-		ksft_exit_skip("No userfaultfd permissions, try running as root.\n");
-	ASSERT_NE(uffd, -1);
-
-	ASSERT_EQ(ioctl(uffd, UFFDIO_API, &api), 0);
-
-	/* Map 10 pages. */
-	ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
-		   MAP_ANON | MAP_PRIVATE, -1, 0);
-	ASSERT_NE(ptr, MAP_FAILED);
-
-	/* Register the range with uffd. */
-	range.start = (unsigned long)ptr;
-	range.len = 10 * page_size;
-	reg.range = range;
-	reg.mode = UFFDIO_REGISTER_MODE_MISSING;
-	ASSERT_EQ(ioctl(uffd, UFFDIO_REGISTER, &reg), 0);
-
-	/* Guard the range. This should not trigger the uffd. */
-	ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
-
-	/* The guarding should behave as usual with no uffd intervention. */
-	for (i = 0; i < 10; i++) {
-		char *curr = &ptr[i * page_size];
-
-		ASSERT_FALSE(try_read_write_buf(curr));
-	}
-
-	/* Cleanup. */
-	ASSERT_EQ(ioctl(uffd, UFFDIO_UNREGISTER, &range), 0);
-	close(uffd);
-	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
-}
-
-TEST_HARNESS_MAIN