[PATCH 3/3] selftests/mm: add memory failure dirty pagecache test

[Miaohe Lin <linmiaohe@huawei.com>]

This patch adds a new testcase to validate memory failure handling for
dirty pagecache. This performs similar operations as clean pagecaches
except fsync() is not used to keep pages dirty.

This test helps ensure that memory failure handling for dirty pagecache
works correctly, including proper SIGBUS delivery, page isolation, and
recovery paths.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 tools/testing/selftests/mm/memory-failure.c | 58 +++++++++++++++++++--
 1 file changed, 54 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/mm/memory-failure.c b/tools/testing/selftests/mm/memory-failure.c
index 41bc669cef60..275ab1c6de0c 100644
--- a/tools/testing/selftests/mm/memory-failure.c
+++ b/tools/testing/selftests/mm/memory-failure.c
@@ -26,8 +26,10 @@ enum inject_type {
 enum result_type {
 	MADV_HARD_ANON,
 	MADV_HARD_CLEAN_PAGECACHE,
+	MADV_HARD_DIRTY_PAGECACHE,
 	MADV_SOFT_ANON,
 	MADV_SOFT_CLEAN_PAGECACHE,
+	MADV_SOFT_DIRTY_PAGECACHE,
 };
 
 static jmp_buf signal_jmp_buf;
@@ -159,6 +161,7 @@ static void check(struct __test_metadata *_metadata, FIXTURE_DATA(memory_failure
 	case MADV_SOFT_ANON:
 	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);
 
@@ -169,6 +172,7 @@ static void check(struct __test_metadata *_metadata, FIXTURE_DATA(memory_failure
 		ASSERT_NE(pagemap_get_pfn(self->pagemap_fd, vaddr), self->pfn);
 		break;
 	case MADV_HARD_ANON:
+	case MADV_HARD_DIRTY_PAGECACHE:
 		/* The SIGBUS signal should have been received. */
 		ASSERT_EQ(setjmp, 1);
 
@@ -241,18 +245,27 @@ TEST_F(memory_failure, anon)
 	ASSERT_EQ(munmap(addr, self->page_size), 0);
 }
 
+static int prepare_file(const char *fname, unsigned long size)
+{
+	int fd;
+
+	fd = open(fname, O_RDWR | O_CREAT, 0664);
+	if (fd >= 0) {
+		unlink(fname);
+		ftruncate(fd, size);
+	}
+	return fd;
+}
+
 TEST_F(memory_failure, clean_pagecache)
 {
-	const char *fname = "./clean-page-cache-test-file";
 	int fd;
 	char *addr;
 	int ret;
 
-	fd = open(fname, O_RDWR | O_CREAT, 0664);
+	fd = prepare_file("./clean-page-cache-test-file", self->page_size);
 	if (fd < 0)
 		SKIP(return, "failed to open test file.\n");
-	unlink(fname);
-	ftruncate(fd, self->page_size);
 
 	addr = mmap(0, self->page_size, PROT_READ | PROT_WRITE,
 		    MAP_SHARED, fd, 0);
@@ -282,4 +295,41 @@ TEST_F(memory_failure, clean_pagecache)
 	ASSERT_EQ(close(fd), 0);
 }
 
+TEST_F(memory_failure, dirty_pagecache)
+{
+	int fd;
+	char *addr;
+	int ret;
+
+	fd = prepare_file("./dirty-page-cache-test-file", self->page_size);
+	if (fd < 0)
+		SKIP(return, "failed to open test file.\n");
+
+	addr = mmap(0, self->page_size, PROT_READ | PROT_WRITE,
+		    MAP_SHARED, fd, 0);
+	if (addr == MAP_FAILED)
+		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 (!self->triggered) {
+		self->triggered = true;
+		ASSERT_EQ(variant->inject(self, addr), 0);
+		FORCE_READ(*addr);
+	}
+
+	if (variant->type == MADV_HARD)
+		check(_metadata, self, addr, MADV_HARD_DIRTY_PAGECACHE, ret);
+	else
+		check(_metadata, self, addr, MADV_SOFT_DIRTY_PAGECACHE, ret);
+
+	cleanup(_metadata, self, addr);
+
+	ASSERT_EQ(munmap(addr, self->page_size), 0);
+
+	ASSERT_EQ(close(fd), 0);
+}
+
 TEST_HARNESS_MAIN
-- 
2.33.0