| Message ID | 20210511150734.3492-2-glittao@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v5,1/3] kunit: make test->lock irq safe | expand |
On Tue, 11 May 2021 at 17:07, <glittao@gmail.com> wrote: > From: Oliver Glitta <glittao@gmail.com> > > SLUB has resiliency_test() function which is hidden behind #ifdef > SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody > runs it. KUnit should be a 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_SLUB_KUNIT_TEST in Kconfig. > Tests next_pointer, first_word and clobber_50th_byte do not run > with KASAN option on. Because the test deliberately modifies non-allocated > objects. > > Use kunit_resource to count errors in cache and silence bug reports. > Count error whenever slab_bug() or slab_fix() is called or when > the count of pages is wrong. > > Signed-off-by: Oliver Glitta <glittao@gmail.com> I think I had already reviewed v4, and the changes here are fine: Reviewed-by: Marco Elver <elver@google.com> Others who had reviewed/acked v4, probably need to re-ack/review. Note, I think if you addressed the comments and didn't change much else, you can typically carry the acks/reviews, unless the other person changed their mind explicitly. > --- > Changes since v4 > Use two tests with KASAN dependency. > Remove setting current test during init and exit. > > Changes since v3 > > Use kunit_resource to silence bug reports and count errors suggested by > Marco Elver. > Make the test depends on !KASAN thanks to report from the kernel test robot. > > Changes since v2 > > Use bit operation & instead of logical && as reported by kernel test > robot and Dan Carpenter > > Changes since v1 > > Conversion from kselftest to KUnit test suggested by Marco Elver. > Error silencing. > Error counting improvements. > > lib/Kconfig.debug | 12 ++++ > lib/Makefile | 1 + > lib/slub_kunit.c | 155 ++++++++++++++++++++++++++++++++++++++++++++++ > mm/slab.h | 1 + > mm/slub.c | 46 +++++++++++++- > 5 files changed, 212 insertions(+), 3 deletions(-) > create mode 100644 lib/slub_kunit.c > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 678c13967580..7723f58a9394 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -2429,6 +2429,18 @@ config BITS_TEST > > If unsure, say N. > > +config SLUB_KUNIT_TEST > + tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS > + depends on SLUB_DEBUG && KUNIT > + default KUNIT_ALL_TESTS > + help > + This builds SLUB allocator unit test. > + Tests SLUB cache debugging functionality. > + For more information on KUnit and unit tests in general please refer > + to the KUnit documentation in Documentation/dev-tools/kunit/. > + > + If unsure, say N. > + > config TEST_UDELAY > tristate "udelay test driver" > help > diff --git a/lib/Makefile b/lib/Makefile > index e11cfc18b6c0..386215dcb0a0 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -353,5 +353,6 @@ obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o > obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o > obj-$(CONFIG_BITS_TEST) += test_bits.o > obj-$(CONFIG_CMDLINE_KUNIT_TEST) += cmdline_kunit.o > +obj-$(CONFIG_SLUB_KUNIT_TEST) += slub_kunit.o > > obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o > diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c > new file mode 100644 > index 000000000000..f28965f64ef6 > --- /dev/null > +++ b/lib/slub_kunit.c > @@ -0,0 +1,155 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include <kunit/test.h> > +#include <linux/mm.h> > +#include <linux/slab.h> > +#include <linux/module.h> > +#include <linux/kernel.h> > +#include "../mm/slab.h" > + > +static struct kunit_resource resource; > +static int slab_errors; > + > +static void test_clobber_zone(struct kunit *test) > +{ > + struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_alloc", 64, 0, > + SLAB_RED_ZONE, NULL); > + u8 *p = kmem_cache_alloc(s, GFP_KERNEL); > + > + kasan_disable_current(); > + p[64] = 0x12; > + > + validate_slab_cache(s); > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > + > + kasan_enable_current(); > + kmem_cache_free(s, p); > + kmem_cache_destroy(s); > +} > + > +#ifndef CONFIG_KASAN > +static void test_next_pointer(struct kunit *test) > +{ > + struct kmem_cache *s = kmem_cache_create("TestSlub_next_ptr_free", 64, 0, > + SLAB_POISON, NULL); > + u8 *p = kmem_cache_alloc(s, GFP_KERNEL); > + unsigned long tmp; > + unsigned long *ptr_addr; > + > + kmem_cache_free(s, p); > + > + ptr_addr = (unsigned long *)(p + s->offset); > + tmp = *ptr_addr; > + p[s->offset] = 0x12; > + > + /* > + * Expecting three errors. > + * One for the corrupted freechain and the other one for the wrong > + * count of objects in use. The third error is fixing broken cache. > + */ > + validate_slab_cache(s); > + KUNIT_EXPECT_EQ(test, 3, slab_errors); > + > + /* > + * Try to repair corrupted freepointer. > + * Still expecting two errors. The first for the wrong count > + * of objects in use. > + * The second error is for fixing broken cache. > + */ > + *ptr_addr = tmp; > + slab_errors = 0; > + > + validate_slab_cache(s); > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > + > + /* > + * Previous validation repaired the count of objects in use. > + * Now expecting no error. > + */ > + slab_errors = 0; > + validate_slab_cache(s); > + KUNIT_EXPECT_EQ(test, 0, slab_errors); > + > + kmem_cache_destroy(s); > +} > + > +static void test_first_word(struct kunit *test) > +{ > + 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; > + > + validate_slab_cache(s); > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > + > + kmem_cache_destroy(s); > +} > + > +static void test_clobber_50th_byte(struct kunit *test) > +{ > + 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; > + > + validate_slab_cache(s); > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > + > + kmem_cache_destroy(s); > +} > +#endif > + > +static void test_clobber_redzone_free(struct kunit *test) > +{ > + struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_free", 64, 0, > + SLAB_RED_ZONE, NULL); > + u8 *p = kmem_cache_alloc(s, GFP_KERNEL); > + > + kasan_disable_current(); > + kmem_cache_free(s, p); > + p[64] = 0xab; > + > + validate_slab_cache(s); > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > + > + kasan_enable_current(); > + kmem_cache_destroy(s); > +} > + > +static int test_init(struct kunit *test) > +{ > + slab_errors = 0; > + > + kunit_add_named_resource(test, NULL, NULL, &resource, > + "slab_errors", &slab_errors); > + return 0; > +} > + > +static void test_exit(struct kunit *test) {} Does removing test_exit() and not setting it below work? > +static struct kunit_case test_cases[] = { > + KUNIT_CASE(test_clobber_zone), > + > +#ifndef CONFIG_KASAN > + KUNIT_CASE(test_next_pointer), > + KUNIT_CASE(test_first_word), > + KUNIT_CASE(test_clobber_50th_byte), > +#endif > + > + KUNIT_CASE(test_clobber_redzone_free), > + {} This is better, and tells us which tests exactly were the ones causing problems with KASAN. > +}; > + > +static struct kunit_suite test_suite = { > + .name = "slub_test", > + .init = test_init, > + .exit = test_exit, > + .test_cases = test_cases, > +}; > +kunit_test_suite(test_suite); > + > +MODULE_LICENSE("GPL"); > diff --git a/mm/slab.h b/mm/slab.h > index 18c1927cd196..9b690fa44cae 100644 > --- a/mm/slab.h > +++ b/mm/slab.h > @@ -215,6 +215,7 @@ DECLARE_STATIC_KEY_TRUE(slub_debug_enabled); > 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); > #else > static inline void print_tracking(struct kmem_cache *s, void *object) > { > diff --git a/mm/slub.c b/mm/slub.c > index feda53ae62ba..985fd6ef033c 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -35,6 +35,7 @@ > #include <linux/prefetch.h> > #include <linux/memcontrol.h> > #include <linux/random.h> > +#include <kunit/test.h> > > #include <trace/events/kmem.h> > > @@ -447,6 +448,26 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, > static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; > static DEFINE_SPINLOCK(object_map_lock); > > +#if IS_ENABLED(CONFIG_KUNIT) > +static bool slab_add_kunit_errors(void) > +{ > + struct kunit_resource *resource; > + > + if (likely(!current->kunit_test)) > + return false; > + > + resource = kunit_find_named_resource(current->kunit_test, "slab_errors"); > + if (!resource) > + return false; > + > + (*(int *)resource->data)++; > + kunit_put_resource(resource); > + return true; > +} > +#else > +static inline bool slab_add_kunit_errors(void) { return false; } > +#endif > + > /* > * Determine a map of object in use on a page. > * > @@ -677,6 +698,9 @@ static void slab_fix(struct kmem_cache *s, char *fmt, ...) > struct va_format vaf; > va_list args; > > + if (slab_add_kunit_errors()) > + return; > + > va_start(args, fmt); > vaf.fmt = fmt; > vaf.va = &args; > @@ -740,6 +764,9 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p) > void object_err(struct kmem_cache *s, struct page *page, > u8 *object, char *reason) > { > + if (slab_add_kunit_errors()) > + return; > + > slab_bug(s, "%s", reason); > print_trailer(s, page, object); > } > @@ -750,6 +777,9 @@ static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, > va_list args; > char buf[100]; > > + if (slab_add_kunit_errors()) > + return; > + > va_start(args, fmt); > vsnprintf(buf, sizeof(buf), fmt, args); > va_end(args); > @@ -799,12 +829,16 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, > while (end > fault && end[-1] == value) > end--; > > + if (slab_add_kunit_errors()) > + goto skip_bug_print; > + > slab_bug(s, "%s overwritten", what); > pr_err("0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n", > fault, end - 1, fault - addr, > fault[0], value); > print_trailer(s, page, object); > > +skip_bug_print: > restore_bytes(s, what, value, fault, end); > return 0; > } > @@ -4662,9 +4696,11 @@ static int validate_slab_node(struct kmem_cache *s, > validate_slab(s, page); > 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); > + slab_add_kunit_errors(); > + } > > if (!(s->flags & SLAB_STORE_USER)) > goto out; > @@ -4673,16 +4709,18 @@ static int validate_slab_node(struct kmem_cache *s, > validate_slab(s, page); > 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)); > + slab_add_kunit_errors(); > + } > > 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 node; > unsigned long count = 0; > @@ -4694,6 +4732,8 @@ static long validate_slab_cache(struct kmem_cache *s) > > return count; > } > +EXPORT_SYMBOL(validate_slab_cache); > + > /* > * Generate lists of code addresses where slabcache objects are allocated > * and freed. > -- > 2.31.1.272.g89b43f80a5 >
On 5/11/21 5:16 PM, Marco Elver wrote: > On Tue, 11 May 2021 at 17:07, <glittao@gmail.com> wrote: >> From: Oliver Glitta <glittao@gmail.com> >> >> SLUB has resiliency_test() function which is hidden behind #ifdef >> SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody >> runs it. KUnit should be a 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_SLUB_KUNIT_TEST in Kconfig. >> Tests next_pointer, first_word and clobber_50th_byte do not run >> with KASAN option on. Because the test deliberately modifies non-allocated >> objects. >> >> Use kunit_resource to count errors in cache and silence bug reports. >> Count error whenever slab_bug() or slab_fix() is called or when >> the count of pages is wrong. >> >> Signed-off-by: Oliver Glitta <glittao@gmail.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > I think I had already reviewed v4, and the changes here are fine: > > Reviewed-by: Marco Elver <elver@google.com> > > Others who had reviewed/acked v4, probably need to re-ack/review. > Note, I think if you addressed the comments and didn't change much > else, you can typically carry the acks/reviews, unless the other > person changed their mind explicitly. FTR, besides me and Marco, v4 had also: Acked-by: Daniel Latypov <dlatypov@google.com>
ut 11. 5. 2021 o 17:16 Marco Elver <elver@google.com> napísal(a): > > On Tue, 11 May 2021 at 17:07, <glittao@gmail.com> wrote: > > From: Oliver Glitta <glittao@gmail.com> > > > > SLUB has resiliency_test() function which is hidden behind #ifdef > > SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody > > runs it. KUnit should be a 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_SLUB_KUNIT_TEST in Kconfig. > > Tests next_pointer, first_word and clobber_50th_byte do not run > > with KASAN option on. Because the test deliberately modifies non-allocated > > objects. > > > > Use kunit_resource to count errors in cache and silence bug reports. > > Count error whenever slab_bug() or slab_fix() is called or when > > the count of pages is wrong. > > > > Signed-off-by: Oliver Glitta <glittao@gmail.com> > > I think I had already reviewed v4, and the changes here are fine: > > Reviewed-by: Marco Elver <elver@google.com> Thank you again. I’m sorry about, I forgot to add this tags. > Others who had reviewed/acked v4, probably need to re-ack/review. > Note, I think if you addressed the comments and didn't change much > else, you can typically carry the acks/reviews, unless the other > person changed their mind explicitly. > > > --- > > Changes since v4 > > Use two tests with KASAN dependency. > > Remove setting current test during init and exit. > > > > Changes since v3 > > > > Use kunit_resource to silence bug reports and count errors suggested by > > Marco Elver. > > Make the test depends on !KASAN thanks to report from the kernel test robot. > > > > Changes since v2 > > > > Use bit operation & instead of logical && as reported by kernel test > > robot and Dan Carpenter > > > > Changes since v1 > > > > Conversion from kselftest to KUnit test suggested by Marco Elver. > > Error silencing. > > Error counting improvements. > > > > lib/Kconfig.debug | 12 ++++ > > lib/Makefile | 1 + > > lib/slub_kunit.c | 155 ++++++++++++++++++++++++++++++++++++++++++++++ > > mm/slab.h | 1 + > > mm/slub.c | 46 +++++++++++++- > > 5 files changed, 212 insertions(+), 3 deletions(-) > > create mode 100644 lib/slub_kunit.c > > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index 678c13967580..7723f58a9394 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -2429,6 +2429,18 @@ config BITS_TEST > > > > If unsure, say N. > > > > +config SLUB_KUNIT_TEST > > + tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS > > + depends on SLUB_DEBUG && KUNIT > > + default KUNIT_ALL_TESTS > > + help > > + This builds SLUB allocator unit test. > > + Tests SLUB cache debugging functionality. > > + For more information on KUnit and unit tests in general please refer > > + to the KUnit documentation in Documentation/dev-tools/kunit/. > > + > > + If unsure, say N. > > + > > config TEST_UDELAY > > tristate "udelay test driver" > > help > > diff --git a/lib/Makefile b/lib/Makefile > > index e11cfc18b6c0..386215dcb0a0 100644 > > --- a/lib/Makefile > > +++ b/lib/Makefile > > @@ -353,5 +353,6 @@ obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o > > obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o > > obj-$(CONFIG_BITS_TEST) += test_bits.o > > obj-$(CONFIG_CMDLINE_KUNIT_TEST) += cmdline_kunit.o > > +obj-$(CONFIG_SLUB_KUNIT_TEST) += slub_kunit.o > > > > obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o > > diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c > > new file mode 100644 > > index 000000000000..f28965f64ef6 > > --- /dev/null > > +++ b/lib/slub_kunit.c > > @@ -0,0 +1,155 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +#include <kunit/test.h> > > +#include <linux/mm.h> > > +#include <linux/slab.h> > > +#include <linux/module.h> > > +#include <linux/kernel.h> > > +#include "../mm/slab.h" > > + > > +static struct kunit_resource resource; > > +static int slab_errors; > > + > > +static void test_clobber_zone(struct kunit *test) > > +{ > > + struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_alloc", 64, 0, > > + SLAB_RED_ZONE, NULL); > > + u8 *p = kmem_cache_alloc(s, GFP_KERNEL); > > + > > + kasan_disable_current(); > > + p[64] = 0x12; > > + > > + validate_slab_cache(s); > > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > > + > > + kasan_enable_current(); > > + kmem_cache_free(s, p); > > + kmem_cache_destroy(s); > > +} > > + > > +#ifndef CONFIG_KASAN > > +static void test_next_pointer(struct kunit *test) > > +{ > > + struct kmem_cache *s = kmem_cache_create("TestSlub_next_ptr_free", 64, 0, > > + SLAB_POISON, NULL); > > + u8 *p = kmem_cache_alloc(s, GFP_KERNEL); > > + unsigned long tmp; > > + unsigned long *ptr_addr; > > + > > + kmem_cache_free(s, p); > > + > > + ptr_addr = (unsigned long *)(p + s->offset); > > + tmp = *ptr_addr; > > + p[s->offset] = 0x12; > > + > > + /* > > + * Expecting three errors. > > + * One for the corrupted freechain and the other one for the wrong > > + * count of objects in use. The third error is fixing broken cache. > > + */ > > + validate_slab_cache(s); > > + KUNIT_EXPECT_EQ(test, 3, slab_errors); > > + > > + /* > > + * Try to repair corrupted freepointer. > > + * Still expecting two errors. The first for the wrong count > > + * of objects in use. > > + * The second error is for fixing broken cache. > > + */ > > + *ptr_addr = tmp; > > + slab_errors = 0; > > + > > + validate_slab_cache(s); > > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > > + > > + /* > > + * Previous validation repaired the count of objects in use. > > + * Now expecting no error. > > + */ > > + slab_errors = 0; > > + validate_slab_cache(s); > > + KUNIT_EXPECT_EQ(test, 0, slab_errors); > > + > > + kmem_cache_destroy(s); > > +} > > + > > +static void test_first_word(struct kunit *test) > > +{ > > + 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; > > + > > + validate_slab_cache(s); > > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > > + > > + kmem_cache_destroy(s); > > +} > > + > > +static void test_clobber_50th_byte(struct kunit *test) > > +{ > > + 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; > > + > > + validate_slab_cache(s); > > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > > + > > + kmem_cache_destroy(s); > > +} > > +#endif > > + > > +static void test_clobber_redzone_free(struct kunit *test) > > +{ > > + struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_free", 64, 0, > > + SLAB_RED_ZONE, NULL); > > + u8 *p = kmem_cache_alloc(s, GFP_KERNEL); > > + > > + kasan_disable_current(); > > + kmem_cache_free(s, p); > > + p[64] = 0xab; > > + > > + validate_slab_cache(s); > > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > > + > > + kasan_enable_current(); > > + kmem_cache_destroy(s); > > +} > > + > > +static int test_init(struct kunit *test) > > +{ > > + slab_errors = 0; > > + > > + kunit_add_named_resource(test, NULL, NULL, &resource, > > + "slab_errors", &slab_errors); > > + return 0; > > +} > > + > > +static void test_exit(struct kunit *test) {} > > Does removing test_exit() and not setting it below work? Yes this works. Thank you for that. I try to remove function but I didn't think about not setting it, so it didn't work. I will fix it. > > +static struct kunit_case test_cases[] = { > > + KUNIT_CASE(test_clobber_zone), > > + > > +#ifndef CONFIG_KASAN > > + KUNIT_CASE(test_next_pointer), > > + KUNIT_CASE(test_first_word), > > + KUNIT_CASE(test_clobber_50th_byte), > > +#endif > > + > > + KUNIT_CASE(test_clobber_redzone_free), > > + {} > > This is better, and tells us which tests exactly were the ones causing > problems with KASAN. > > > > +}; > > + > > +static struct kunit_suite test_suite = { > > + .name = "slub_test", > > + .init = test_init, > > + .exit = test_exit, > > + .test_cases = test_cases, > > +}; > > +kunit_test_suite(test_suite); > > + > > +MODULE_LICENSE("GPL"); > > diff --git a/mm/slab.h b/mm/slab.h > > index 18c1927cd196..9b690fa44cae 100644 > > --- a/mm/slab.h > > +++ b/mm/slab.h > > @@ -215,6 +215,7 @@ DECLARE_STATIC_KEY_TRUE(slub_debug_enabled); > > 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); > > #else > > static inline void print_tracking(struct kmem_cache *s, void *object) > > { > > diff --git a/mm/slub.c b/mm/slub.c > > index feda53ae62ba..985fd6ef033c 100644 > > --- a/mm/slub.c > > +++ b/mm/slub.c > > @@ -35,6 +35,7 @@ > > #include <linux/prefetch.h> > > #include <linux/memcontrol.h> > > #include <linux/random.h> > > +#include <kunit/test.h> > > > > #include <trace/events/kmem.h> > > > > @@ -447,6 +448,26 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, > > static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; > > static DEFINE_SPINLOCK(object_map_lock); > > > > +#if IS_ENABLED(CONFIG_KUNIT) > > +static bool slab_add_kunit_errors(void) > > +{ > > + struct kunit_resource *resource; > > + > > + if (likely(!current->kunit_test)) > > + return false; > > + > > + resource = kunit_find_named_resource(current->kunit_test, "slab_errors"); > > + if (!resource) > > + return false; > > + > > + (*(int *)resource->data)++; > > + kunit_put_resource(resource); > > + return true; > > +} > > +#else > > +static inline bool slab_add_kunit_errors(void) { return false; } > > +#endif > > + > > /* > > * Determine a map of object in use on a page. > > * > > @@ -677,6 +698,9 @@ static void slab_fix(struct kmem_cache *s, char *fmt, ...) > > struct va_format vaf; > > va_list args; > > > > + if (slab_add_kunit_errors()) > > + return; > > + > > va_start(args, fmt); > > vaf.fmt = fmt; > > vaf.va = &args; > > @@ -740,6 +764,9 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p) > > void object_err(struct kmem_cache *s, struct page *page, > > u8 *object, char *reason) > > { > > + if (slab_add_kunit_errors()) > > + return; > > + > > slab_bug(s, "%s", reason); > > print_trailer(s, page, object); > > } > > @@ -750,6 +777,9 @@ static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, > > va_list args; > > char buf[100]; > > > > + if (slab_add_kunit_errors()) > > + return; > > + > > va_start(args, fmt); > > vsnprintf(buf, sizeof(buf), fmt, args); > > va_end(args); > > @@ -799,12 +829,16 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, > > while (end > fault && end[-1] == value) > > end--; > > > > + if (slab_add_kunit_errors()) > > + goto skip_bug_print; > > + > > slab_bug(s, "%s overwritten", what); > > pr_err("0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n", > > fault, end - 1, fault - addr, > > fault[0], value); > > print_trailer(s, page, object); > > > > +skip_bug_print: > > restore_bytes(s, what, value, fault, end); > > return 0; > > } > > @@ -4662,9 +4696,11 @@ static int validate_slab_node(struct kmem_cache *s, > > validate_slab(s, page); > > 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); > > + slab_add_kunit_errors(); > > + } > > > > if (!(s->flags & SLAB_STORE_USER)) > > goto out; > > @@ -4673,16 +4709,18 @@ static int validate_slab_node(struct kmem_cache *s, > > validate_slab(s, page); > > 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)); > > + slab_add_kunit_errors(); > > + } > > > > 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 node; > > unsigned long count = 0; > > @@ -4694,6 +4732,8 @@ static long validate_slab_cache(struct kmem_cache *s) > > > > return count; > > } > > +EXPORT_SYMBOL(validate_slab_cache); > > + > > /* > > * Generate lists of code addresses where slabcache objects are allocated > > * and freed. > > -- > > 2.31.1.272.g89b43f80a5 > >
On Tue, 11 May 2021 17:07:33 +0200 glittao@gmail.com wrote: > From: Oliver Glitta <glittao@gmail.com> > > SLUB has resiliency_test() function which is hidden behind #ifdef > SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody > runs it. KUnit should be a 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_SLUB_KUNIT_TEST in Kconfig. > Tests next_pointer, first_word and clobber_50th_byte do not run > with KASAN option on. Because the test deliberately modifies non-allocated > objects. > > Use kunit_resource to count errors in cache and silence bug reports. > Count error whenever slab_bug() or slab_fix() is called or when > the count of pages is wrong. > > ... > > lib/slub_kunit.c | 155 ++++++++++++++++++++++++++++++++++++++++++++++ > mm/slab.h | 1 + > mm/slub.c | 46 +++++++++++++- > 5 files changed, 212 insertions(+), 3 deletions(-) > create mode 100644 lib/slub_kunit.c > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 678c13967580..7723f58a9394 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -2429,6 +2429,18 @@ config BITS_TEST > > If unsure, say N. > > +config SLUB_KUNIT_TEST > + tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS This means it can be compiled as a kernel module. Did you runtime test the code as a module? ERROR: modpost: "kasan_enable_current" [lib/slub_kunit.ko] undefined! ERROR: modpost: "kasan_disable_current" [lib/slub_kunit.ko] undefined! --- a/mm/kasan/common.c~a +++ a/mm/kasan/common.c @@ -51,11 +51,14 @@ void kasan_enable_current(void) { current->kasan_depth++; } +EXPORT_SYMBOL(kasan_enable_current); void kasan_disable_current(void) { current->kasan_depth--; } +EXPORT_SYMBOL(kasan_disable_current); + #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */ void __kasan_unpoison_range(const void *address, size_t size)
On Thu, 13 May 2021 at 06:44, Andrew Morton <akpm@linux-foundation.org> wrote: > On Tue, 11 May 2021 17:07:33 +0200 glittao@gmail.com wrote: > > From: Oliver Glitta <glittao@gmail.com> > > > > SLUB has resiliency_test() function which is hidden behind #ifdef > > SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody > > runs it. KUnit should be a 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_SLUB_KUNIT_TEST in Kconfig. > > Tests next_pointer, first_word and clobber_50th_byte do not run > > with KASAN option on. Because the test deliberately modifies non-allocated > > objects. > > > > Use kunit_resource to count errors in cache and silence bug reports. > > Count error whenever slab_bug() or slab_fix() is called or when > > the count of pages is wrong. > > > > ... > > > > lib/slub_kunit.c | 155 ++++++++++++++++++++++++++++++++++++++++++++++ > > mm/slab.h | 1 + > > mm/slub.c | 46 +++++++++++++- > > 5 files changed, 212 insertions(+), 3 deletions(-) > > create mode 100644 lib/slub_kunit.c > > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index 678c13967580..7723f58a9394 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -2429,6 +2429,18 @@ config BITS_TEST > > > > If unsure, say N. > > > > +config SLUB_KUNIT_TEST > > + tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS > > This means it can be compiled as a kernel module. Did you runtime test the > code as a module? > > ERROR: modpost: "kasan_enable_current" [lib/slub_kunit.ko] undefined! > ERROR: modpost: "kasan_disable_current" [lib/slub_kunit.ko] undefined! > > --- a/mm/kasan/common.c~a > +++ a/mm/kasan/common.c > @@ -51,11 +51,14 @@ void kasan_enable_current(void) > { > current->kasan_depth++; > } > +EXPORT_SYMBOL(kasan_enable_current); > > void kasan_disable_current(void) > { > current->kasan_depth--; > } > +EXPORT_SYMBOL(kasan_disable_current); > + > #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */ > > void __kasan_unpoison_range(const void *address, size_t size) > _ Acked-by: Marco Elver <elver@google.com>
št 13. 5. 2021 o 6:44 Andrew Morton <akpm@linux-foundation.org> napísal(a): > > On Tue, 11 May 2021 17:07:33 +0200 glittao@gmail.com wrote: > > > From: Oliver Glitta <glittao@gmail.com> > > > > SLUB has resiliency_test() function which is hidden behind #ifdef > > SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody > > runs it. KUnit should be a 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_SLUB_KUNIT_TEST in Kconfig. > > Tests next_pointer, first_word and clobber_50th_byte do not run > > with KASAN option on. Because the test deliberately modifies non-allocated > > objects. > > > > Use kunit_resource to count errors in cache and silence bug reports. > > Count error whenever slab_bug() or slab_fix() is called or when > > the count of pages is wrong. > > > > ... > > > > lib/slub_kunit.c | 155 ++++++++++++++++++++++++++++++++++++++++++++++ > > mm/slab.h | 1 + > > mm/slub.c | 46 +++++++++++++- > > 5 files changed, 212 insertions(+), 3 deletions(-) > > create mode 100644 lib/slub_kunit.c > > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index 678c13967580..7723f58a9394 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -2429,6 +2429,18 @@ config BITS_TEST > > > > If unsure, say N. > > > > +config SLUB_KUNIT_TEST > > + tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS > > This means it can be compiled as a kernel module. Did you runtime test the > code as a module? > We tested this as a module in the previous version, but I forgot to try it with this new one. So we didn't find this error. Thank you for your fix. > ERROR: modpost: "kasan_enable_current" [lib/slub_kunit.ko] undefined! > ERROR: modpost: "kasan_disable_current" [lib/slub_kunit.ko] undefined! > > --- a/mm/kasan/common.c~a > +++ a/mm/kasan/common.c > @@ -51,11 +51,14 @@ void kasan_enable_current(void) > { > current->kasan_depth++; > } > +EXPORT_SYMBOL(kasan_enable_current); > > void kasan_disable_current(void) > { > current->kasan_depth--; > } > +EXPORT_SYMBOL(kasan_disable_current); > + > #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */ > > void __kasan_unpoison_range(const void *address, size_t size) > _ >
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 678c13967580..7723f58a9394 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2429,6 +2429,18 @@ config BITS_TEST If unsure, say N. +config SLUB_KUNIT_TEST + tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS + depends on SLUB_DEBUG && KUNIT + default KUNIT_ALL_TESTS + help + This builds SLUB allocator unit test. + Tests SLUB cache debugging functionality. + For more information on KUnit and unit tests in general please refer + to the KUnit documentation in Documentation/dev-tools/kunit/. + + If unsure, say N. + config TEST_UDELAY tristate "udelay test driver" help diff --git a/lib/Makefile b/lib/Makefile index e11cfc18b6c0..386215dcb0a0 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -353,5 +353,6 @@ obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o obj-$(CONFIG_BITS_TEST) += test_bits.o obj-$(CONFIG_CMDLINE_KUNIT_TEST) += cmdline_kunit.o +obj-$(CONFIG_SLUB_KUNIT_TEST) += slub_kunit.o obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c new file mode 100644 index 000000000000..f28965f64ef6 --- /dev/null +++ b/lib/slub_kunit.c @@ -0,0 +1,155 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <kunit/test.h> +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include "../mm/slab.h" + +static struct kunit_resource resource; +static int slab_errors; + +static void test_clobber_zone(struct kunit *test) +{ + struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_alloc", 64, 0, + SLAB_RED_ZONE, NULL); + u8 *p = kmem_cache_alloc(s, GFP_KERNEL); + + kasan_disable_current(); + p[64] = 0x12; + + validate_slab_cache(s); + KUNIT_EXPECT_EQ(test, 2, slab_errors); + + kasan_enable_current(); + kmem_cache_free(s, p); + kmem_cache_destroy(s); +} + +#ifndef CONFIG_KASAN +static void test_next_pointer(struct kunit *test) +{ + struct kmem_cache *s = kmem_cache_create("TestSlub_next_ptr_free", 64, 0, + SLAB_POISON, NULL); + u8 *p = kmem_cache_alloc(s, GFP_KERNEL); + unsigned long tmp; + unsigned long *ptr_addr; + + kmem_cache_free(s, p); + + ptr_addr = (unsigned long *)(p + s->offset); + tmp = *ptr_addr; + p[s->offset] = 0x12; + + /* + * Expecting three errors. + * One for the corrupted freechain and the other one for the wrong + * count of objects in use. The third error is fixing broken cache. + */ + validate_slab_cache(s); + KUNIT_EXPECT_EQ(test, 3, slab_errors); + + /* + * Try to repair corrupted freepointer. + * Still expecting two errors. The first for the wrong count + * of objects in use. + * The second error is for fixing broken cache. + */ + *ptr_addr = tmp; + slab_errors = 0; + + validate_slab_cache(s); + KUNIT_EXPECT_EQ(test, 2, slab_errors); + + /* + * Previous validation repaired the count of objects in use. + * Now expecting no error. + */ + slab_errors = 0; + validate_slab_cache(s); + KUNIT_EXPECT_EQ(test, 0, slab_errors); + + kmem_cache_destroy(s); +} + +static void test_first_word(struct kunit *test) +{ + 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; + + validate_slab_cache(s); + KUNIT_EXPECT_EQ(test, 2, slab_errors); + + kmem_cache_destroy(s); +} + +static void test_clobber_50th_byte(struct kunit *test) +{ + 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; + + validate_slab_cache(s); + KUNIT_EXPECT_EQ(test, 2, slab_errors); + + kmem_cache_destroy(s); +} +#endif + +static void test_clobber_redzone_free(struct kunit *test) +{ + struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_free", 64, 0, + SLAB_RED_ZONE, NULL); + u8 *p = kmem_cache_alloc(s, GFP_KERNEL); + + kasan_disable_current(); + kmem_cache_free(s, p); + p[64] = 0xab; + + validate_slab_cache(s); + KUNIT_EXPECT_EQ(test, 2, slab_errors); + + kasan_enable_current(); + kmem_cache_destroy(s); +} + +static int test_init(struct kunit *test) +{ + slab_errors = 0; + + kunit_add_named_resource(test, NULL, NULL, &resource, + "slab_errors", &slab_errors); + return 0; +} + +static void test_exit(struct kunit *test) {} + +static struct kunit_case test_cases[] = { + KUNIT_CASE(test_clobber_zone), + +#ifndef CONFIG_KASAN + KUNIT_CASE(test_next_pointer), + KUNIT_CASE(test_first_word), + KUNIT_CASE(test_clobber_50th_byte), +#endif + + KUNIT_CASE(test_clobber_redzone_free), + {} +}; + +static struct kunit_suite test_suite = { + .name = "slub_test", + .init = test_init, + .exit = test_exit, + .test_cases = test_cases, +}; +kunit_test_suite(test_suite); + +MODULE_LICENSE("GPL"); diff --git a/mm/slab.h b/mm/slab.h index 18c1927cd196..9b690fa44cae 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -215,6 +215,7 @@ DECLARE_STATIC_KEY_TRUE(slub_debug_enabled); 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); #else static inline void print_tracking(struct kmem_cache *s, void *object) { diff --git a/mm/slub.c b/mm/slub.c index feda53ae62ba..985fd6ef033c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -35,6 +35,7 @@ #include <linux/prefetch.h> #include <linux/memcontrol.h> #include <linux/random.h> +#include <kunit/test.h> #include <trace/events/kmem.h> @@ -447,6 +448,26 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; static DEFINE_SPINLOCK(object_map_lock); +#if IS_ENABLED(CONFIG_KUNIT) +static bool slab_add_kunit_errors(void) +{ + struct kunit_resource *resource; + + if (likely(!current->kunit_test)) + return false; + + resource = kunit_find_named_resource(current->kunit_test, "slab_errors"); + if (!resource) + return false; + + (*(int *)resource->data)++; + kunit_put_resource(resource); + return true; +} +#else +static inline bool slab_add_kunit_errors(void) { return false; } +#endif + /* * Determine a map of object in use on a page. * @@ -677,6 +698,9 @@ static void slab_fix(struct kmem_cache *s, char *fmt, ...) struct va_format vaf; va_list args; + if (slab_add_kunit_errors()) + return; + va_start(args, fmt); vaf.fmt = fmt; vaf.va = &args; @@ -740,6 +764,9 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p) void object_err(struct kmem_cache *s, struct page *page, u8 *object, char *reason) { + if (slab_add_kunit_errors()) + return; + slab_bug(s, "%s", reason); print_trailer(s, page, object); } @@ -750,6 +777,9 @@ static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, va_list args; char buf[100]; + if (slab_add_kunit_errors()) + return; + va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); @@ -799,12 +829,16 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, while (end > fault && end[-1] == value) end--; + if (slab_add_kunit_errors()) + goto skip_bug_print; + slab_bug(s, "%s overwritten", what); pr_err("0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n", fault, end - 1, fault - addr, fault[0], value); print_trailer(s, page, object); +skip_bug_print: restore_bytes(s, what, value, fault, end); return 0; } @@ -4662,9 +4696,11 @@ static int validate_slab_node(struct kmem_cache *s, validate_slab(s, page); 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); + slab_add_kunit_errors(); + } if (!(s->flags & SLAB_STORE_USER)) goto out; @@ -4673,16 +4709,18 @@ static int validate_slab_node(struct kmem_cache *s, validate_slab(s, page); 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)); + slab_add_kunit_errors(); + } 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 node; unsigned long count = 0; @@ -4694,6 +4732,8 @@ static long validate_slab_cache(struct kmem_cache *s) return count; } +EXPORT_SYMBOL(validate_slab_cache); + /* * Generate lists of code addresses where slabcache objects are allocated * and freed.