The patch titled
Subject: selftests: add a kselftest for SLUB debugging functionality
has been added to the -mm tree. Its filename is
selftests-add-a-kselftest-for-slub-debugging-functionality.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/selftests-add-a-kselftest-for-slub-debugging-functionality.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/selftests-add-a-kselftest-for-slub-debugging-functionality.patch
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------------------------------------------------------
From: Oliver Glitta <glittao@xxxxxxxxx>
Subject: selftests: add a kselftest for SLUB debugging functionality
SLUB has resiliency_test() function which is hidden behind #ifdef
SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody runs it.
Kselftest should proper replacement for it.
Try changing byte in redzone after allocation and changing pointer to next
free node, first byte, 50th byte and redzone byte. Check if validation
finds errors.
There are several differences from the original resiliency test: Tests
create own caches with known state instead of corrupting shared kmalloc
caches.
The corruption of freepointer uses correct offset, the original resiliency
test got broken with freepointer changes.
Scratch changing random byte test, because it does not have meaning in
this form where we need deterministic results.
Add new option CONFIG_TEST_SLUB in Kconfig.
Add parameter to function validate_slab_cache() to return number of errors
in cache.
Link: https://lkml.kernel.org/r/20210316124118.6874-1-glittao@xxxxxxxxx
Signed-off-by: Oliver Glitta <glittao@xxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/Kconfig.debug | 4
lib/Makefile | 1
lib/test_slub.c | 125 +++++++++++++++++++++++++
mm/slab.h | 1
mm/slub.c | 34 ++++--
tools/testing/selftests/lib/Makefile | 2
tools/testing/selftests/lib/config | 1
tools/testing/selftests/lib/slub.sh | 3
8 files changed, 159 insertions(+), 12 deletions(-)
--- a/lib/Kconfig.debug~selftests-add-a-kselftest-for-slub-debugging-functionality
+++ a/lib/Kconfig.debug
@@ -2123,6 +2123,10 @@ config TEST_KSTRTOX
config TEST_PRINTF
tristate "Test printf() family of functions at runtime"
+config TEST_SLUB
+ tristate "Test SLUB cache errors at runtime"
+ depends on SLUB_DEBUG
+
config TEST_BITMAP
tristate "Test bitmap_*() family of functions at runtime"
help
--- a/lib/Makefile~selftests-add-a-kselftest-for-slub-debugging-functionality
+++ a/lib/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_TEST_USER_COPY) += test_use
obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
obj-$(CONFIG_TEST_PRINTF) += test_printf.o
+obj-$(CONFIG_TEST_SLUB) += test_slub.o
obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
obj-$(CONFIG_TEST_STRSCPY) += test_strscpy.o
obj-$(CONFIG_TEST_UUID) += test_uuid.o
--- /dev/null
+++ a/lib/test_slub.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Test cases for slub facility.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include "../mm/slab.h"
+
+#include "../tools/testing/selftests/kselftest_module.h"
+
+
+KSTM_MODULE_GLOBALS();
+
+
+static void __init validate_result(struct kmem_cache *s, int expected_errors)
+{
+ int errors = 0;
+
+ validate_slab_cache(s, &errors);
+ KSTM_CHECK_ZERO(errors - expected_errors);
+}
+
+static void __init test_clobber_zone(void)
+{
+ struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_alloc", 64, 0,
+ SLAB_RED_ZONE, NULL);
+ u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
+
+ p[64] = 0x12;
+ pr_err("1. kmem_cache: Clobber Redzone 0x12->0x%p\n", p + 64);
+
+ validate_result(s, 1);
+ kmem_cache_free(s, p);
+ kmem_cache_destroy(s);
+}
+
+static void __init test_next_pointer(void)
+{
+ struct kmem_cache *s = kmem_cache_create("TestSlub_next_ptr_free", 64, 0,
+ SLAB_RED_ZONE, NULL);
+ u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
+
+ kmem_cache_free(s, p);
+ p[s->offset] = 0x12;
+ pr_err("1. kmem_cache: Clobber next pointer 0x34 -> -0x%p\n", p);
+
+ validate_result(s, 1);
+ kmem_cache_destroy(s);
+}
+
+static void __init test_first_word(void)
+{
+ struct kmem_cache *s = kmem_cache_create("TestSlub_1th_word_free", 64, 0,
+ SLAB_POISON, NULL);
+ u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
+
+ kmem_cache_free(s, p);
+ *p = 0x78;
+ pr_err("2. kmem_cache: Clobber first word 0x78->0x%p\n", p);
+
+ validate_result(s, 1);
+ kmem_cache_destroy(s);
+}
+
+static void __init test_clobber_50th_byte(void)
+{
+ struct kmem_cache *s = kmem_cache_create("TestSlub_50th_word_free", 64, 0,
+ SLAB_POISON, NULL);
+ u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
+
+ kmem_cache_free(s, p);
+ p[50] = 0x9a;
+ pr_err("3. kmem_cache: Clobber 50th byte 0x9a->0x%p\n", p);
+
+ validate_result(s, 1);
+ kmem_cache_destroy(s);
+}
+
+static void __init test_clobber_redzone_free(void)
+{
+ struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_free", 64, 0,
+ SLAB_RED_ZONE, NULL);
+ u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
+
+ kmem_cache_free(s, p);
+ p[64] = 0xab;
+ pr_err("4. kmem_cache: Clobber redzone 0xab->0x%p\n", p);
+
+ validate_result(s, 1);
+ kmem_cache_destroy(s);
+}
+
+static void __init resiliency_test(void)
+{
+
+ BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10);
+
+ pr_err("SLUB resiliency testing\n");
+ pr_err("-----------------------\n");
+ pr_err("A. Corruption after allocation\n");
+
+ test_clobber_zone();
+
+ pr_err("\nB. Corruption after free\n");
+
+ test_next_pointer();
+ test_first_word();
+ test_clobber_50th_byte();
+ test_clobber_redzone_free();
+}
+
+
+static void __init selftest(void)
+{
+ resiliency_test();
+}
+
+
+KSTM_MODULE_LOADERS(test_slub);
+MODULE_LICENSE("GPL");
--- a/mm/slab.h~selftests-add-a-kselftest-for-slub-debugging-functionality
+++ a/mm/slab.h
@@ -215,6 +215,7 @@ DECLARE_STATIC_KEY_TRUE(slub_debug_enabl
DECLARE_STATIC_KEY_FALSE(slub_debug_enabled);
#endif
extern void print_tracking(struct kmem_cache *s, void *object);
+long validate_slab_cache(struct kmem_cache *s, int *errors);
#else
static inline void print_tracking(struct kmem_cache *s, void *object)
{
--- a/mm/slub.c~selftests-add-a-kselftest-for-slub-debugging-functionality
+++ a/mm/slub.c
@@ -4621,7 +4621,8 @@ static int count_total(struct page *page
#endif
#ifdef CONFIG_SLUB_DEBUG
-static void validate_slab(struct kmem_cache *s, struct page *page)
+static void validate_slab(struct kmem_cache *s, struct page *page,
+ int *errors)
{
void *p;
void *addr = page_address(page);
@@ -4629,8 +4630,10 @@ static void validate_slab(struct kmem_ca
slab_lock(page);
- if (!check_slab(s, page) || !on_freelist(s, page, NULL))
+ if (!check_slab(s, page) || !on_freelist(s, page, NULL)) {
+ *errors += 1;
goto unlock;
+ }
/* Now we know that a valid freelist exists */
map = get_map(s, page);
@@ -4638,8 +4641,10 @@ static void validate_slab(struct kmem_ca
u8 val = test_bit(__obj_to_index(s, addr, p), map) ?
SLUB_RED_INACTIVE : SLUB_RED_ACTIVE;
- if (!check_object(s, page, p, val))
+ if (!check_object(s, page, p, val)) {
+ *errors += 1;
break;
+ }
}
put_map(map);
unlock:
@@ -4647,7 +4652,7 @@ unlock:
}
static int validate_slab_node(struct kmem_cache *s,
- struct kmem_cache_node *n)
+ struct kmem_cache_node *n, int *errors)
{
unsigned long count = 0;
struct page *page;
@@ -4656,30 +4661,34 @@ static int validate_slab_node(struct kme
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(page, &n->partial, slab_list) {
- validate_slab(s, page);
+ validate_slab(s, page, errors);
count++;
}
- if (count != n->nr_partial)
+ if (count != n->nr_partial) {
pr_err("SLUB %s: %ld partial slabs counted but counter=%ld\n",
s->name, count, n->nr_partial);
+ *errors += 1;
+ }
if (!(s->flags & SLAB_STORE_USER))
goto out;
list_for_each_entry(page, &n->full, slab_list) {
- validate_slab(s, page);
+ validate_slab(s, page, errors);
count++;
}
- if (count != atomic_long_read(&n->nr_slabs))
+ if (count != atomic_long_read(&n->nr_slabs)) {
pr_err("SLUB: %s %ld slabs counted but counter=%ld\n",
s->name, count, atomic_long_read(&n->nr_slabs));
+ *errors += 1;
+ }
out:
spin_unlock_irqrestore(&n->list_lock, flags);
return count;
}
-static long validate_slab_cache(struct kmem_cache *s)
+long validate_slab_cache(struct kmem_cache *s, int *errors)
{
int node;
unsigned long count = 0;
@@ -4687,10 +4696,12 @@ static long validate_slab_cache(struct k
flush_all(s);
for_each_kmem_cache_node(s, node, n)
- count += validate_slab_node(s, n);
+ count += validate_slab_node(s, n, errors);
return count;
}
+EXPORT_SYMBOL(validate_slab_cache);
+
/*
* Generate lists of code addresses where slabcache objects are allocated
* and freed.
@@ -5345,9 +5356,10 @@ static ssize_t validate_store(struct kme
const char *buf, size_t length)
{
int ret = -EINVAL;
+ int errors = 0;
if (buf[0] == '1') {
- ret = validate_slab_cache(s);
+ ret = validate_slab_cache(s, &errors);
if (ret >= 0)
ret = length;
}
--- a/tools/testing/selftests/lib/config~selftests-add-a-kselftest-for-slub-debugging-functionality
+++ a/tools/testing/selftests/lib/config
@@ -3,3 +3,4 @@ CONFIG_TEST_BITMAP=m
CONFIG_PRIME_NUMBERS=m
CONFIG_TEST_STRSCPY=m
CONFIG_TEST_BITOPS=m
+CONFIG_TEST_SLUB=m
\ No newline at end of file
--- a/tools/testing/selftests/lib/Makefile~selftests-add-a-kselftest-for-slub-debugging-functionality
+++ a/tools/testing/selftests/lib/Makefile
@@ -4,6 +4,6 @@
# No binaries, but make sure arg-less "make" doesn't trigger "run_tests"
all:
-TEST_PROGS := printf.sh bitmap.sh prime_numbers.sh strscpy.sh
+TEST_PROGS := printf.sh bitmap.sh prime_numbers.sh strscpy.sh slub.sh
include ../lib.mk
--- /dev/null
+++ a/tools/testing/selftests/lib/slub.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+$(dirname $0)/../kselftest/module.sh "slub" test_slub
_
Patches currently in -mm which might be from glittao@xxxxxxxxx are
selftests-add-a-kselftest-for-slub-debugging-functionality.patch
slub-remove-resiliency_test-function.patch
