From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-23.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81D93C433ED for ; Tue, 13 Apr 2021 13:54:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B1366117A for ; Tue, 13 Apr 2021 13:54:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231768AbhDMNyq (ORCPT ); Tue, 13 Apr 2021 09:54:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346219AbhDMNyk (ORCPT ); Tue, 13 Apr 2021 09:54:40 -0400 Received: from mail-oi1-x22a.google.com (mail-oi1-x22a.google.com [IPv6:2607:f8b0:4864:20::22a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF9BDC061756 for ; Tue, 13 Apr 2021 06:54:19 -0700 (PDT) Received: by mail-oi1-x22a.google.com with SMTP id x77so7671813oix.8 for ; Tue, 13 Apr 2021 06:54:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=ShLbnr1P8rkomLYtDMJuS+GJV1J/N9tQY9gZZ3VLsqM=; b=momaoOWW1dQyvXZhp8dQKNr+tfrSuO3BzjtKbBNiLtCrmH7CIXWRXpBehLKG+mWy0x DfNhg5CGtE89yl60qDwj91BM8H19taA3n7pUtqykfsMJdDLAoRlSlIhWdFKalpNLFSYB CzH9kgmlZ+1bhTxdu1qvBKbSLr3Vn7ZBlcnRo6YUCC7gji+uGOjypQ8mjTBVPv63HQfk jqiROXEYrGFVA7cGJ82dUbxGM2rjdt7nl3isxIeP9/HdF3nFu21aLRYsOv1vn9qh8kaO KKas+ezzUo3mvlhftkMKc0TYB5kzRuQMzw3JGm17jrDxXigG6Pv2Y0RbuHleZII1KaTd TDzA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ShLbnr1P8rkomLYtDMJuS+GJV1J/N9tQY9gZZ3VLsqM=; b=IXkpBxFH8mQq2ZqXPRNiPNw3qgQWRUVy2HrzgzUgQmLe9FhZqjQ0xn4mMbv2sx+uiA mPxNxKozBWcbGad17GjBg6agb5DRqKieFLQem5K4M8W3MZv1mlQ6OMXwSkvhq+wMabsv kG30iZzvfNBdJaTo+Jlx2xvzT1QYJOPjD3lHzqPaj5ZqVGVclWM8Kk2fxCrxv46sD2sc oEdyVx1RZjbnIEZuuiOygg0jIQo2JUz8lu9GYDn0e2VDDdly3lXFpEf+SPCjIXT6wSdp 3UDAC0Z/ZWM3XPqf3pDBK/79yz/zdV4U5hVTfbIMOO7j1dfeiB1aBo5k8/v0dZHRKuJa 3axw== X-Gm-Message-State: AOAM530E7br5Ms3eP4SA2gDifps007MDBFN2A2pjj46H1erbXJfQR+Jp A1/DQPmZeOo1YApXqq2YdNfcNMqjVIV7rUFgi4Wolw== X-Google-Smtp-Source: ABdhPJz8sgcfKMPwDhaTisfENtsAh8kiIYb3fQ+WXEuQ7QEY2BXwGlzMye8wDd+3KT2NkWL0fQ3R+m0LXP1N1CWfNl8= X-Received: by 2002:aca:408a:: with SMTP id n132mr114803oia.70.1618322058975; Tue, 13 Apr 2021 06:54:18 -0700 (PDT) MIME-Version: 1.0 References: <20210413100747.4921-1-glittao@gmail.com> <20210413100747.4921-2-glittao@gmail.com> In-Reply-To: <20210413100747.4921-2-glittao@gmail.com> From: Marco Elver Date: Tue, 13 Apr 2021 15:54:06 +0200 Message-ID: Subject: Re: [PATCH v4 2/3] mm/slub, kunit: add a KUnit test for SLUB debugging functionality To: glittao@gmail.com Cc: Brendan Higgins , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , LKML , "open list:KERNEL SELFTEST FRAMEWORK" , KUnit Development , Linux Memory Management List , Daniel Latypov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Tue, 13 Apr 2021 at 12:07, wrote: > From: Oliver Glitta > > 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. > Because the test deliberatly modifies non-allocated objects, it depends on > !KASAN which would have otherwise prevented that. Hmm, did the test fail with KASAN? Is it possible to skip the tests and still run a subset of tests with KASAN? It'd be nice if we could run some of these tests with KASAN as well. > 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 Reviewed-by: Marco Elver Thanks, this all looks good to me. But perhaps do test what works with KASAN, to see if you need the !KASAN constraint for all cases. > --- > 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 | 150 ++++++++++++++++++++++++++++++++++++++++++++++ > mm/slab.h | 1 + > mm/slub.c | 50 ++++++++++++++-- > 5 files changed, 209 insertions(+), 5 deletions(-) > create mode 100644 lib/slub_kunit.c > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 2779c29d9981..9b8a0d754278 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -2371,6 +2371,18 @@ 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 && !KASAN > + 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 b5307d3eec1a..1e59c6714ed8 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -352,5 +352,6 @@ 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..cb9ae9f7e8a6 > --- /dev/null > +++ b/lib/slub_kunit.c > @@ -0,0 +1,150 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include > +#include > +#include > +#include > +#include > +#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); > + > + p[64] = 0x12; > + > + validate_slab_cache(s); > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > + > + kmem_cache_free(s, p); > + kmem_cache_destroy(s); > +} > + > +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); > +} > + > +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); > + > + kmem_cache_free(s, p); > + p[64] = 0xab; > + > + validate_slab_cache(s); > + KUNIT_EXPECT_EQ(test, 2, slab_errors); > + kmem_cache_destroy(s); > +} > + > +static int test_init(struct kunit *test) > +{ > + slab_errors = 0; > + > + /* FIXME: remove when CONFIG_KASAN requirement is dropped. */ > + current->kunit_test = test; Note, the patch "kunit: support failure from dynamic analysis tools" is already in -next. It's probably safe to leave this, and send a follow-up patch later once that kunit patch is in mainline. > + kunit_add_named_resource(test, NULL, NULL, &resource, > + "slab_errors", &slab_errors); > + return 0; > +} > + > +static void test_exit(struct kunit *test) > +{ > + /* FIXME: remove when CONFIG_KASAN requirement is dropped. */ > + current->kunit_test = NULL; > +} > + > +static struct kunit_case test_cases[] = { > + KUNIT_CASE(test_clobber_zone), > + KUNIT_CASE(test_next_pointer), > + KUNIT_CASE(test_first_word), > + KUNIT_CASE(test_clobber_50th_byte), > + 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 076582f58f68..95cf42eb8396 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 3021ce9bf1b3..d7df8841d90a 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -35,6 +35,7 @@ > #include > #include > #include > +#include > > #include > > @@ -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. > * > @@ -676,6 +697,9 @@ 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; > @@ -739,6 +763,9 @@ 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); > } > @@ -749,6 +776,9 @@ 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); > @@ -798,12 +828,16 @@ 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("INFO: 0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n", > - fault, end - 1, fault - addr, > - fault[0], value); > + 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; > } > @@ -4650,9 +4684,11 @@ 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; > @@ -4661,16 +4697,18 @@ 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; > @@ -4682,6 +4720,8 @@ 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 >