selftests/mm: add memory failure anonymous page test

Patch series "selftests/mm: add memory failure selftests", v4.

Introduce selftests to validate the functionality of memory failure. 
These tests help ensure that memory failure handling for anonymous pages,
pagecaches pages works correctly, including proper SIGBUS delivery to user
processes, page isolation, and recovery paths.

Currently madvise syscall is used to inject memory failures.  And only
anonymous pages and pagecaches are tested.  More test scenarios, e.g. 
hugetlb, shmem, thp, will be added.  Also more memory failure injecting
methods will be supported, e.g.  APEI Error INJection, if required.


This patch (of 3):

This patch adds a new kselftest to validate memory failure handling for
anonymous pages. The test performs the following operations:
1. Allocates anonymous pages using mmap().
2. Injects memory failure via madvise syscall.
3. Verifies expected error handling behavior.
4. Unpoison memory.

This test helps ensure that memory failure handling for anonymous pages
works correctly, including proper SIGBUS delivery to user processes, page
isolation and recovery paths.

Link: https://lkml.kernel.org/r/20260206031639.2707102-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20260206031639.2707102-2-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@kernel.org>
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>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

MAINTAINERS

@@ -11691,6 +11691,7 @@ F:	include/linux/memory-failure.h
 F:	include/trace/events/memory-failure.h
 F:	mm/hwpoison-inject.c
 F:	mm/memory-failure.c
+F:	tools/testing/selftests/mm/memory-failure.c
 
 HYCON HY46XX TOUCHSCREEN SUPPORT
 M:	Giulio Benetti <giulio.benetti@benettiengineering.com>

tools/testing/selftests/mm/.gitignore

@@ -12,6 +12,7 @@ map_hugetlb
 map_populate
 thuge-gen
 compaction_test
+memory-failure
 migration
 mlock2-tests
 mrelease_test

tools/testing/selftests/mm/Makefile

@@ -75,6 +75,7 @@ TEST_GEN_FILES += map_populate
 ifneq (,$(filter $(ARCH),arm64 riscv riscv64 x86 x86_64))
 TEST_GEN_FILES += memfd_secret
 endif
+TEST_GEN_FILES += memory-failure
 TEST_GEN_FILES += migration
 TEST_GEN_FILES += mkdirty
 TEST_GEN_FILES += mlock-random-test
@@ -154,6 +155,7 @@ TEST_PROGS += ksft_ksm_numa.sh
 TEST_PROGS += ksft_madv_guard.sh
 TEST_PROGS += ksft_madv_populate.sh
 TEST_PROGS += ksft_memfd_secret.sh
+TEST_PROGS += ksft_memory_failure.sh
 TEST_PROGS += ksft_migration.sh
 TEST_PROGS += ksft_mkdirty.sh
 TEST_PROGS += ksft_mlock.sh

tools/testing/selftests/mm/config

@@ -11,3 +11,5 @@ CONFIG_ANON_VMA_NAME=y
 CONFIG_FTRACE=y
 CONFIG_PROFILING=y
 CONFIG_UPROBES=y
+CONFIG_MEMORY_FAILURE=y
+CONFIG_HWPOISON_INJECT=m

tools/testing/selftests/mm/ksft_memory_failure.sh

@@ -0,0 +1,4 @@
+#!/bin/sh -e
+# SPDX-License-Identifier: GPL-2.0
+
+./run_vmtests.sh -t memory-failure

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

@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Memory-failure functional tests.
+ *
+ * Author(s): Miaohe Lin <linmiaohe@huawei.com>
+ */
+
+#include "../kselftest_harness.h"
+
+#include <sys/mman.h>
+#include <linux/mman.h>
+#include <linux/string.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "vm_util.h"
+
+enum inject_type {
+	MADV_HARD,
+	MADV_SOFT,
+};
+
+enum result_type {
+	MADV_HARD_ANON,
+	MADV_SOFT_ANON,
+};
+
+static jmp_buf signal_jmp_buf;
+static siginfo_t siginfo;
+const char *pagemap_proc = "/proc/self/pagemap";
+const char *kpageflags_proc = "/proc/kpageflags";
+
+FIXTURE(memory_failure)
+{
+	unsigned long page_size;
+	unsigned long corrupted_size;
+	unsigned long pfn;
+	int pagemap_fd;
+	int kpageflags_fd;
+	bool triggered;
+};
+
+FIXTURE_VARIANT(memory_failure)
+{
+	enum inject_type type;
+	int (*inject)(FIXTURE_DATA(memory_failure) * self, void *vaddr);
+};
+
+static int madv_hard_inject(FIXTURE_DATA(memory_failure) * self, void *vaddr)
+{
+	return madvise(vaddr, self->page_size, MADV_HWPOISON);
+}
+
+FIXTURE_VARIANT_ADD(memory_failure, madv_hard)
+{
+	.type = MADV_HARD,
+	.inject = madv_hard_inject,
+};
+
+static int madv_soft_inject(FIXTURE_DATA(memory_failure) * self, void *vaddr)
+{
+	return madvise(vaddr, self->page_size, MADV_SOFT_OFFLINE);
+}
+
+FIXTURE_VARIANT_ADD(memory_failure, madv_soft)
+{
+	.type = MADV_SOFT,
+	.inject = madv_soft_inject,
+};
+
+static void sigbus_action(int signo, siginfo_t *si, void *args)
+{
+	memcpy(&siginfo, si, sizeof(siginfo_t));
+	siglongjmp(signal_jmp_buf, 1);
+}
+
+static int setup_sighandler(void)
+{
+	struct sigaction sa = {
+		.sa_sigaction = sigbus_action,
+		.sa_flags = SA_SIGINFO,
+	};
+
+	return sigaction(SIGBUS, &sa, NULL);
+}
+
+FIXTURE_SETUP(memory_failure)
+{
+	memset(self, 0, sizeof(*self));
+
+	self->page_size = (unsigned long)sysconf(_SC_PAGESIZE);
+
+	memset(&siginfo, 0, sizeof(siginfo));
+	if (setup_sighandler())
+		SKIP(return, "setup sighandler failed.\n");
+
+	self->pagemap_fd = open(pagemap_proc, O_RDONLY);
+	if (self->pagemap_fd == -1)
+		SKIP(return, "open %s failed.\n", pagemap_proc);
+
+	self->kpageflags_fd = open(kpageflags_proc, O_RDONLY);
+	if (self->kpageflags_fd == -1)
+		SKIP(return, "open %s failed.\n", kpageflags_proc);
+}
+
+static void teardown_sighandler(void)
+{
+	struct sigaction sa = {
+		.sa_handler = SIG_DFL,
+		.sa_flags = SA_SIGINFO,
+	};
+
+	sigaction(SIGBUS, &sa, NULL);
+}
+
+FIXTURE_TEARDOWN(memory_failure)
+{
+	close(self->kpageflags_fd);
+	close(self->pagemap_fd);
+	teardown_sighandler();
+}
+
+static void prepare(struct __test_metadata *_metadata, FIXTURE_DATA(memory_failure) * self,
+		    void *vaddr)
+{
+	self->pfn = pagemap_get_pfn(self->pagemap_fd, vaddr);
+	ASSERT_NE(self->pfn, -1UL);
+
+	ASSERT_EQ(get_hardware_corrupted_size(&self->corrupted_size), 0);
+}
+
+static bool check_memory(void *vaddr, unsigned long size)
+{
+	char buf[64];
+
+	memset(buf, 0xce, sizeof(buf));
+	while (size >= sizeof(buf)) {
+		if (memcmp(vaddr, buf, sizeof(buf)))
+			return false;
+		size -= sizeof(buf);
+		vaddr += sizeof(buf);
+	}
+
+	return true;
+}
+
+static void check(struct __test_metadata *_metadata, FIXTURE_DATA(memory_failure) * self,
+		  void *vaddr, enum result_type type, int setjmp)
+{
+	unsigned long size;
+	uint64_t pfn_flags;
+
+	switch (type) {
+	case MADV_SOFT_ANON:
+		/* It is not expected to receive a SIGBUS signal. */
+		ASSERT_EQ(setjmp, 0);
+
+		/* The page content should remain unchanged. */
+		ASSERT_TRUE(check_memory(vaddr, self->page_size));
+
+		/* The backing pfn of addr should have changed. */
+		ASSERT_NE(pagemap_get_pfn(self->pagemap_fd, vaddr), self->pfn);
+		break;
+	case MADV_HARD_ANON:
+		/* The SIGBUS signal should have been received. */
+		ASSERT_EQ(setjmp, 1);
+
+		/* Check if siginfo contains correct SIGBUS context. */
+		ASSERT_EQ(siginfo.si_signo, SIGBUS);
+		ASSERT_EQ(siginfo.si_code, BUS_MCEERR_AR);
+		ASSERT_EQ(1UL << siginfo.si_addr_lsb, self->page_size);
+		ASSERT_EQ(siginfo.si_addr, vaddr);
+
+		/* XXX Check backing pte is hwpoison entry when supported. */
+		ASSERT_TRUE(pagemap_is_swapped(self->pagemap_fd, vaddr));
+		break;
+	default:
+		SKIP(return, "unexpected inject type %d.\n", type);
+	}
+
+	/* Check if the value of HardwareCorrupted has increased. */
+	ASSERT_EQ(get_hardware_corrupted_size(&size), 0);
+	ASSERT_EQ(size, self->corrupted_size + self->page_size / 1024);
+
+	/* Check if HWPoison flag is set. */
+	ASSERT_EQ(pageflags_get(self->pfn, self->kpageflags_fd, &pfn_flags), 0);
+	ASSERT_EQ(pfn_flags & KPF_HWPOISON, KPF_HWPOISON);
+}
+
+static void cleanup(struct __test_metadata *_metadata, FIXTURE_DATA(memory_failure) * self,
+		    void *vaddr)
+{
+	unsigned long size;
+	uint64_t pfn_flags;
+
+	ASSERT_EQ(unpoison_memory(self->pfn), 0);
+
+	/* Check if HWPoison flag is cleared. */
+	ASSERT_EQ(pageflags_get(self->pfn, self->kpageflags_fd, &pfn_flags), 0);
+	ASSERT_NE(pfn_flags & KPF_HWPOISON, KPF_HWPOISON);
+
+	/* Check if the value of HardwareCorrupted has decreased. */
+	ASSERT_EQ(get_hardware_corrupted_size(&size), 0);
+	ASSERT_EQ(size, self->corrupted_size);
+}
+
+TEST_F(memory_failure, anon)
+{
+	char *addr;
+	int ret;
+
+	addr = mmap(0, self->page_size, PROT_READ | PROT_WRITE,
+		    MAP_ANONYMOUS | MAP_PRIVATE, -1, 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_ANON, ret);
+	else
+		check(_metadata, self, addr, MADV_SOFT_ANON, ret);
+
+	cleanup(_metadata, self, addr);
+
+	ASSERT_EQ(munmap(addr, self->page_size), 0);
+}
+
+TEST_HARNESS_MAIN

tools/testing/selftests/mm/run_vmtests.sh

@@ -91,6 +91,8 @@ separated by spaces:
 	test VMA merge cases behave as expected
 - rmap
 	test rmap behaves as expected
+- memory-failure
+	test memory-failure behaves as expected
 
 example: ./run_vmtests.sh -t "hmm mmap ksm"
 EOF
@@ -527,6 +529,25 @@ CATEGORY="page_frag" run_test ./test_page_frag.sh nonaligned
 
 CATEGORY="rmap" run_test ./rmap
 
+# Try to load hwpoison_inject if not present.
+HWPOISON_DIR=/sys/kernel/debug/hwpoison/
+if [ ! -d "$HWPOISON_DIR" ]; then
+	if ! modprobe -q -R hwpoison_inject; then
+		echo "Module hwpoison_inject not found, skipping..."
+	else
+		modprobe hwpoison_inject > /dev/null 2>&1
+		LOADED_MOD=1
+	fi
+fi
+
+if [ -d "$HWPOISON_DIR" ]; then
+	CATEGORY="memory-failure" run_test ./memory-failure
+fi
+
+if [ -n "${LOADED_MOD}" ]; then
+	modprobe -r hwpoison_inject > /dev/null 2>&1
+fi
+
 if [ "${HAVE_HUGEPAGES}" = 1 ]; then
 	echo "$orig_nr_hugepgs" > /proc/sys/vm/nr_hugepages
 fi

tools/testing/selftests/mm/vm_util.c

@@ -723,3 +723,44 @@ int ksm_stop(void)
 	close(ksm_fd);
 	return ret == 1 ? 0 : -errno;
 }
+
+int get_hardware_corrupted_size(unsigned long *val)
+{
+	unsigned long size;
+	char *line = NULL;
+	size_t linelen = 0;
+	FILE *f = fopen("/proc/meminfo", "r");
+	int ret = -1;
+
+	if (!f)
+		return ret;
+
+	while (getline(&line, &linelen, f) > 0) {
+		if (sscanf(line, "HardwareCorrupted: %12lu kB", &size) == 1) {
+			*val = size;
+			ret = 0;
+			break;
+		}
+	}
+
+	free(line);
+	fclose(f);
+	return ret;
+}
+
+int unpoison_memory(unsigned long pfn)
+{
+	int unpoison_fd, len;
+	char buf[32];
+	ssize_t ret;
+
+	unpoison_fd = open("/sys/kernel/debug/hwpoison/unpoison-pfn", O_WRONLY);
+	if (unpoison_fd < 0)
+		return -errno;
+
+	len = sprintf(buf, "0x%lx\n", pfn);
+	ret = write(unpoison_fd, buf, len);
+	close(unpoison_fd);
+
+	return ret > 0 ? 0 : -errno;
+}

tools/testing/selftests/mm/vm_util.h

@@ -20,6 +20,7 @@
 
 #define KPF_COMPOUND_HEAD             BIT_ULL(15)
 #define KPF_COMPOUND_TAIL             BIT_ULL(16)
+#define KPF_HWPOISON                  BIT_ULL(19)
 #define KPF_THP                       BIT_ULL(22)
 /*
  * Ignore the checkpatch warning, we must read from x but don't want to do
@@ -154,6 +155,8 @@ long ksm_get_full_scans(void);
 int ksm_use_zero_pages(void);
 int ksm_start(void);
 int ksm_stop(void);
+int get_hardware_corrupted_size(unsigned long *val);
+int unpoison_memory(unsigned long pfn);
 
 /*
  * On ppc64 this will only work with radix 2M hugepage size