Add a shmem memory failure selftest to test the shmem memory failure is
correct after modifying shmem return value.

Test that
+ madvise() call returns 0 when the poisoned shmem page is clean
+ trigger a SIGBUS when the poisoned shmem page is dirty
+ trigger another SIGBUS when the poisoned shmem page is fault-in again.

Signed-off-by: Lisa Wang <wyihan@google.com>
---
 tools/testing/selftests/mm/memory-failure.c | 109 +++++++++++++++++++++++++++-
 1 file changed, 106 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/memory-failure.c b/tools/testing/selftests/mm/memory-failure.c
index 3d9e0b9ffb41..eb3f8d98f6c9 100644
--- a/tools/testing/selftests/mm/memory-failure.c
+++ b/tools/testing/selftests/mm/memory-failure.c
@@ -30,9 +30,14 @@ enum result_type {
 	MADV_HARD_ANON,
 	MADV_HARD_CLEAN_PAGECACHE,
 	MADV_HARD_DIRTY_PAGECACHE,
+	MADV_HARD_CLEAN_SHMEM,
+	MADV_HARD_DIRTY_SHMEM,
 	MADV_SOFT_ANON,
 	MADV_SOFT_CLEAN_PAGECACHE,
 	MADV_SOFT_DIRTY_PAGECACHE,
+	MADV_SOFT_CLEAN_SHMEM,
+	MADV_SOFT_DIRTY_SHMEM,
+	READ_ERROR,
 };
 
 static jmp_buf signal_jmp_buf;
@@ -165,17 +170,21 @@ static void check(struct __test_metadata *_metadata, FIXTURE_DATA(memory_failure
 	case MADV_HARD_CLEAN_PAGECACHE:
 	case MADV_SOFT_CLEAN_PAGECACHE:
 	case MADV_SOFT_DIRTY_PAGECACHE:
-		/* It is not expected to receive a SIGBUS signal. */
-		ASSERT_EQ(setjmp, 0);
-
+	case MADV_SOFT_DIRTY_SHMEM:
 		/* The page content should remain unchanged. */
 		ASSERT_TRUE(check_memory(vaddr, self->page_size));
+	case MADV_HARD_CLEAN_SHMEM:
+	case MADV_SOFT_CLEAN_SHMEM:
+		/* It is not expected to receive a SIGBUS signal. */
+		ASSERT_EQ(setjmp, 0);
 
 		/* The backing pfn of addr should have changed. */
 		ASSERT_NE(pagemap_get_pfn(self->pagemap_fd, vaddr), self->pfn);
 		break;
 	case MADV_HARD_ANON:
 	case MADV_HARD_DIRTY_PAGECACHE:
+	case MADV_HARD_DIRTY_SHMEM:
+	case READ_ERROR:
 		/* The SIGBUS signal should have been received. */
 		ASSERT_EQ(setjmp, 1);
 
@@ -260,6 +269,20 @@ static int prepare_file(const char *fname, unsigned long size)
 	return fd;
 }
 
+static int prepare_shmem(const char *fname, unsigned long size)
+{
+	int fd;
+
+	fd = memfd_create(fname, 0);
+	if (fd < 0)
+		return -1;
+	if (ftruncate(fd, size) < 0) {
+		close(fd);
+		return -1;
+	}
+	return fd;
+}
+
 /* Borrowed from mm/gup_longterm.c. */
 static int get_fs_type(int fd)
 {
@@ -356,4 +379,84 @@ TEST_F(memory_failure, dirty_pagecache)
 	ASSERT_EQ(close(fd), 0);
 }
 
+TEST_F(memory_failure, dirty_shmem)
+{
+	int fd;
+	char *addr;
+	int ret;
+
+	fd = prepare_shmem("shmem-file", self->page_size);
+	if (fd < 0)
+		SKIP(return, "failed to open test shmem-file.\n");
+
+	addr = mmap(0, self->page_size, PROT_READ | PROT_WRITE,
+		    MAP_SHARED, fd, 0);
+	if (addr == MAP_FAILED) {
+		close(fd);
+		SKIP(return, "mmap failed, not enough memory.\n");
+	}
+	memset(addr, 0xce, self->page_size);
+
+	prepare(_metadata, self, addr);
+
+	ret = sigsetjmp(signal_jmp_buf, 1);
+	if (ret == 0)
+		ASSERT_EQ(variant->inject(self, addr), 0);
+
+	if (variant->type == MADV_HARD) {
+		check(_metadata, self, addr, MADV_HARD_DIRTY_SHMEM, ret);
+		ret = sigsetjmp(signal_jmp_buf, 1);
+		if (ret == 0)
+			FORCE_READ(*addr);
+		check(_metadata, self, addr, READ_ERROR, ret);
+	} else {
+		check(_metadata, self, addr, MADV_SOFT_DIRTY_SHMEM, ret);
+	}
+
+	ASSERT_EQ(munmap(addr, self->page_size), 0);
+
+	ASSERT_EQ(close(fd), 0);
+	cleanup(_metadata, self, addr);
+}
+
+TEST_F(memory_failure, clean_shmem)
+{
+	int fd;
+	char *addr;
+	int ret;
+
+	fd = prepare_shmem("shmem-file", self->page_size);
+	if (fd < 0)
+		SKIP(return, "failed to open test shmem-file.\n");
+
+	addr = mmap(0, self->page_size, PROT_READ | PROT_WRITE,
+		    MAP_SHARED, fd, 0);
+	if (addr == MAP_FAILED) {
+		close(fd);
+		SKIP(return, "mmap failed, not enough memory.\n");
+	}
+	FORCE_READ(*addr);
+
+	prepare(_metadata, self, addr);
+
+	ret = sigsetjmp(signal_jmp_buf, 1);
+	if (ret == 0)
+		ASSERT_EQ(variant->inject(self, addr), 0);
+
+	if (variant->type == MADV_HARD) {
+		check(_metadata, self, addr, MADV_HARD_CLEAN_SHMEM, ret);
+		ret = sigsetjmp(signal_jmp_buf, 1);
+		if (ret == 0)
+			FORCE_READ(*addr);
+		check(_metadata, self, addr, READ_ERROR, ret);
+	} else {
+		check(_metadata, self, addr, MADV_SOFT_CLEAN_SHMEM, ret);
+	}
+
+	ASSERT_EQ(munmap(addr, self->page_size), 0);
+
+	ASSERT_EQ(close(fd), 0);
+	cleanup(_metadata, self, addr);
+}
+
 TEST_HARNESS_MAIN

-- 
2.53.0.1213.gd9a14994de-goog