selftests/mm: add memory failure dirty pagecache test

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.

Link: https://lkml.kernel.org/r/20260206031639.2707102-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: kernel test robot <lkp@intel.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: MiaoheLin

tools/testing/selftests/mm/memory-failure.c

@@ -29,8 +29,10 @@ 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;
@@ -162,6 +164,7 @@ 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);
 
@@ -172,6 +175,7 @@ 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);
 
@@ -244,6 +248,18 @@ 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;
+}
+
 /* Borrowed from mm/gup_longterm.c. */
 static int get_fs_type(int fd)
 {
@@ -259,17 +275,14 @@ static int get_fs_type(int fd)
 
 TEST_F(memory_failure, clean_pagecache)
 {
-	const char *fname = "./clean-page-cache-test-file";
 	int fd;
 	char *addr;
 	int ret;
 	int fs_type;
 
-	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);
 	fs_type = get_fs_type(fd);
 	if (!fs_type || fs_type == TMPFS_MAGIC)
 		SKIP(return, "unsupported filesystem :%x\n", fs_type);
@@ -302,4 +315,45 @@ TEST_F(memory_failure, clean_pagecache)
 	ASSERT_EQ(close(fd), 0);
 }
 
+TEST_F(memory_failure, dirty_pagecache)
+{
+	int fd;
+	char *addr;
+	int ret;
+	int fs_type;
+
+	fd = prepare_file("./dirty-page-cache-test-file", self->page_size);
+	if (fd < 0)
+		SKIP(return, "failed to open test file.\n");
+	fs_type = get_fs_type(fd);
+	if (!fs_type || fs_type == TMPFS_MAGIC)
+		SKIP(return, "unsupported filesystem :%x\n", fs_type);
+
+	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