From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sphereful.davidgow.net (sphereful.davidgow.net [203.29.242.92]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20328439F75; Thu, 15 Oct 2026 14:12:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.29.242.92 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792073542; cv=none; b=q2Jf9CgwfrfnM+hZ2QB8NNE9FLcRVyJugSkYZLbq/UNuXAxxnL9Mse6nL30VGgtpv+MpkQhuEAA/2DqwpFqvt7iRpUWpYFtrzaTn9+lB1IszWdESKvKa4a7WyoF8PpFQI0qPwkIqS/f7xULmibX95LKnyO8tXl6H970AQejuAY0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792073542; c=relaxed/simple; bh=zQjClWTlRSrEDvf3v/4znzjDecAtN82hnrlhsDrNbkw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Fifkz3ZFe+s29sSOBdXIQvQVudTpezBtxIB09Xg+R6q6hrOeDpUsfMWSpYnB/bR3QalMke0kecQRpi9psLPZeLQeb9elHSoRhH32x4rW5/9xrc45SZe3rrVzyLzSjIoRsRW8Lj9fMVqGQ8J0ecwxOmItQEhLLF4rSD0uVIW4sqI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=davidgow.net; spf=pass smtp.mailfrom=davidgow.net; arc=none smtp.client-ip=203.29.242.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=davidgow.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=davidgow.net Received: by sphereful.davidgow.net (Postfix, from userid 119) id DBDE9200617; Thu, 15 Oct 2026 22:05:05 +0800 (AWST) X-Spam-Level: Received: from [192.168.11.49] (ip-178-027-179-026.vkd86.pools.vodafone-ip.de [178.27.179.26]) by sphereful.davidgow.net (Postfix) with ESMTPSA id 4D784200611; Thu, 15 Oct 2026 22:04:57 +0800 (AWST) Message-ID: Date: Thu, 15 Oct 2026 22:04:51 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] lib/sbitmap: add KUnit test suite To: Wang Yibo , Jens Axboe Cc: Andrew Morton , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com References: <20261014082704.33667-1-szwyb123@gmail.com> Content-Language: en-US From: David Gow In-Reply-To: <20261014082704.33667-1-szwyb123@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Le 14/10/2026 à 16:27, Wang Yibo a écrit : > sbitmap is the tag allocator used by blk-mq and the I/O schedulers > built on top of it, but the plain, synchronous part of its API has no > test coverage at all. > > Add a KUnit suite covering initialisation, allocation and exhaustion, > deferred clears, round-robin ordering, resize, the bitmap helpers and > sbitmap_for_each_set(), so that the behaviour is checked on every boot. > > The new file is added to the BLOCK LAYER entry in MAINTAINERS, next to > lib/sbitmap.c, so that it does not end up without a maintainer. > > Signed-off-by: Wang Yibo > --- Thanks for the test. I'll give it a closer look when I'm back from my post-plumbers travel, but it seems that this is failing on a number of architectures. In partciular, sb.alloc_hint is annotated __percpu, which alas doesn't work with KUNIT_EXPECT_NOT_NULL on, e.g., x86 where it uses a different address space (__seg_fs or __seg_gs). This is probably something we should work out how to address in KUnit, but for now you may be better off with a different assertion. Equally, sbitmap_test_iterate_set is failing here on 32-bit UML (but only when built with gcc, not clang): # sbitmap_test_iterate_set: EXPECTATION FAILED at lib/tests/sbitmap_kunit.c:273 Expected ctx.nr_visited == (unsigned int)(sizeof(bits) / sizeof((bits)[0]) + ((int)sizeof(struct {_Static_assert(!(!(!__builtin_types_compatible_p(typeof((bits)), typeof(&(bits)[0])))), "must be array");}))), but ctx.nr_visited == 5 (0x5) (unsigned int)(sizeof(bits) / sizeof((bits)[0]) + ((int)sizeof(struct {_Static_assert(!(!(!__builtin_types_compatible_p(typeof((bits)), typeof(&(bits)[0])))), "must be array");}))) == 6 (0x6) [FAILED] sbitmap_test_iterate_set # module: sbitmap_kunit # sbitmap: pass:7 fail:1 skip:0 total:8 # Totals: pass:7 fail:1 skip:0 total:8 ===================== [FAILED] sbitmap ===================== Not sure what's causing that yet: it may not be an issue with the test itself. Cheers, -- David > MAINTAINERS | 1 + > lib/Kconfig.debug | 13 ++ > lib/tests/Makefile | 1 + > lib/tests/sbitmap_kunit.c | 300 ++++++++++++++++++++++++++++++++++++++ > 4 files changed, 315 insertions(+) > create mode 100644 lib/tests/sbitmap_kunit.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index f53047aa8d3c..c8510e6f1817 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -4726,6 +4726,7 @@ F: include/uapi/linux/blk* > F: include/uapi/linux/ioprio.h > F: kernel/trace/blktrace.c > F: lib/sbitmap.c > +F: lib/tests/sbitmap_kunit.c > > BLOCK LAYER DEVICE DRIVER API [RUST] > M: Andreas Hindborg > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 6b24a2c89b84..f5fe7f5a0a4d 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -2456,6 +2456,19 @@ config PRINTF_KUNIT_TEST > > If unsure, say N. > > +config SBITMAP_KUNIT_TEST > + tristate "KUnit test for sbitmap" if !KUNIT_ALL_TESTS > + depends on KUNIT > + depends on SBITMAP > + default KUNIT_ALL_TESTS > + help > + Enable to turn on sbitmap tests, running at boot or module load time. > + > + 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 SCANF_KUNIT_TEST > tristate "KUnit test scanf() family of functions at runtime" if !KUNIT_ALL_TESTS > depends on KUNIT > diff --git a/lib/tests/Makefile b/lib/tests/Makefile > index 3cac3b63a752..1f49555f94c3 100644 > --- a/lib/tests/Makefile > +++ b/lib/tests/Makefile > @@ -44,6 +44,7 @@ obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o > obj-$(CONFIG_PRANDOM_KUNIT_TEST) += random32_kunit.o > obj-$(CONFIG_PRINTF_KUNIT_TEST) += printf_kunit.o > obj-$(CONFIG_RANDSTRUCT_KUNIT_TEST) += randstruct_kunit.o > +obj-$(CONFIG_SBITMAP_KUNIT_TEST) += sbitmap_kunit.o > obj-$(CONFIG_SCANF_KUNIT_TEST) += scanf_kunit.o > obj-$(CONFIG_SEQ_BUF_KUNIT_TEST) += seq_buf_kunit.o > obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o > diff --git a/lib/tests/sbitmap_kunit.c b/lib/tests/sbitmap_kunit.c > new file mode 100644 > index 000000000000..4f3a588d15df > --- /dev/null > +++ b/lib/tests/sbitmap_kunit.c > @@ -0,0 +1,300 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * KUnit tests for the scalable bitmap (sbitmap) implementation. > + * > + * sbitmap is the tag allocator used by blk-mq and the I/O schedulers built on > + * top of it, but it has no tests. These tests pin down the observable > + * behaviour of the plain, synchronous parts of the API. > + * > + * Copyright (C) 2026 Wang Yibo > + */ > + > +#include > +#include > +#include > + > +#include > + > +/* > + * Big enough to span several words for any plausible BITS_PER_LONG, and not a > + * power of two so that the last word is partially used. > + */ > +#define SBITMAP_TEST_DEPTH (3 * BITS_PER_LONG + 5) > + > +static void sbitmap_test_init(struct kunit *test) > +{ > + const unsigned int depth = 97; > + struct sbitmap sb; > + int ret; > + > + ret = sbitmap_init_node(&sb, depth, -1, GFP_KERNEL, NUMA_NO_NODE, > + false, true); > + KUNIT_ASSERT_EQ(test, ret, 0); > + KUNIT_EXPECT_EQ(test, sb.depth, depth); > + KUNIT_EXPECT_EQ(test, sb.shift, > + (unsigned int)sbitmap_calculate_shift(depth)); > + KUNIT_EXPECT_EQ(test, sb.map_nr, DIV_ROUND_UP(depth, 1U << sb.shift)); > + KUNIT_EXPECT_FALSE(test, sb.round_robin); > + KUNIT_EXPECT_NOT_NULL(test, sb.alloc_hint); alloc_hint is declared __percpu, which is incompatible with KUNIT_EXPECT_NOT_NULL() on x86. > + KUNIT_EXPECT_FALSE(test, sbitmap_any_bit_set(&sb)); > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), 0U); > + sbitmap_free(&sb); > + > + /* An explicitly requested shift is honoured. */ > + ret = sbitmap_init_node(&sb, depth, 3, GFP_KERNEL, NUMA_NO_NODE, > + false, true); > + KUNIT_ASSERT_EQ(test, ret, 0); > + KUNIT_EXPECT_EQ(test, sb.shift, 3U); > + KUNIT_EXPECT_EQ(test, sb.map_nr, DIV_ROUND_UP(depth, 1U << 3)); > + sbitmap_free(&sb); > + > + /* BITS_PER_LONG bits per word is the largest representable granularity. */ > + ret = sbitmap_init_node(&sb, depth, ilog2(BITS_PER_LONG), GFP_KERNEL, > + NUMA_NO_NODE, false, true); > + KUNIT_ASSERT_EQ(test, ret, 0); > + KUNIT_EXPECT_EQ(test, sb.shift, (unsigned int)ilog2(BITS_PER_LONG)); > + KUNIT_EXPECT_EQ(test, sb.map_nr, DIV_ROUND_UP(depth, BITS_PER_LONG)); > + sbitmap_free(&sb); > + > + /* Anything above that cannot be represented and must be rejected. */ > + ret = sbitmap_init_node(&sb, depth, ilog2(BITS_PER_LONG) + 1, > + GFP_KERNEL, NUMA_NO_NODE, false, true); > + KUNIT_EXPECT_EQ(test, ret, -EINVAL); > +} > + > +static void sbitmap_test_calculate_shift(struct kunit *test) > +{ > + /* Maps too small to spread over several words keep the default. */ > + KUNIT_EXPECT_EQ(test, sbitmap_calculate_shift(0), ilog2(BITS_PER_LONG)); > + KUNIT_EXPECT_EQ(test, sbitmap_calculate_shift(1), ilog2(BITS_PER_LONG)); > + KUNIT_EXPECT_EQ(test, sbitmap_calculate_shift(3), ilog2(BITS_PER_LONG)); > + > + /* Four bits map to one bit per word. */ > + KUNIT_EXPECT_EQ(test, sbitmap_calculate_shift(4), 0); > + > + /* The shift grows back as the depth increases. */ > + KUNIT_EXPECT_EQ(test, sbitmap_calculate_shift(4 * BITS_PER_LONG - 1), > + ilog2(BITS_PER_LONG) - 1); > + KUNIT_EXPECT_EQ(test, sbitmap_calculate_shift(4 * BITS_PER_LONG), > + ilog2(BITS_PER_LONG)); > +} > + > +static void sbitmap_test_get_exhaust(struct kunit *test) > +{ > + DECLARE_BITMAP(seen, SBITMAP_TEST_DEPTH) = { 0 }; > + struct sbitmap sb; > + unsigned int i; > + int bit; > + > + KUNIT_ASSERT_EQ(test, sbitmap_init_node(&sb, SBITMAP_TEST_DEPTH, -1, > + GFP_KERNEL, NUMA_NO_NODE, > + false, true), 0); > + > + /* Every bit is handed out exactly once, then the map is empty. */ > + for (i = 0; i < SBITMAP_TEST_DEPTH; i++) { > + bit = sbitmap_get(&sb); > + KUNIT_ASSERT_GE(test, bit, 0); > + KUNIT_ASSERT_LT(test, bit, (int)SBITMAP_TEST_DEPTH); > + KUNIT_ASSERT_FALSE(test, test_bit(bit, seen)); > + __set_bit(bit, seen); > + } > + > + KUNIT_EXPECT_TRUE(test, sbitmap_any_bit_set(&sb)); > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), > + (unsigned int)SBITMAP_TEST_DEPTH); > + KUNIT_EXPECT_EQ(test, sbitmap_get(&sb), -1); > + > + sbitmap_free(&sb); > +} > + > +static void sbitmap_test_put_reuse(struct kunit *test) > +{ > + struct sbitmap sb; > + unsigned int i; > + int bit; > + > + KUNIT_ASSERT_EQ(test, sbitmap_init_node(&sb, BITS_PER_LONG, -1, > + GFP_KERNEL, NUMA_NO_NODE, > + true, true), 0); > + > + for (i = 0; i < BITS_PER_LONG; i++) > + KUNIT_ASSERT_GE(test, sbitmap_get(&sb), 0); > + > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), (unsigned int)BITS_PER_LONG); > + KUNIT_EXPECT_EQ(test, sbitmap_get(&sb), -1); > + > + /* > + * Freeing a single bit must make exactly that bit available again, no > + * matter which bit it was. > + */ > + for (i = 0; i < BITS_PER_LONG; i++) { > + sbitmap_put(&sb, i); > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), > + (unsigned int)BITS_PER_LONG - 1); > + bit = sbitmap_get(&sb); > + KUNIT_EXPECT_EQ(test, bit, (int)i); > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), > + (unsigned int)BITS_PER_LONG); > + KUNIT_EXPECT_EQ(test, sbitmap_get(&sb), -1); > + } > + > + sbitmap_free(&sb); > +} > + > +static void sbitmap_test_round_robin(struct kunit *test) > +{ > + struct sbitmap sb; > + unsigned int i; > + int bit, prev = -1; > + > + KUNIT_ASSERT_EQ(test, sbitmap_init_node(&sb, SBITMAP_TEST_DEPTH, -1, > + GFP_KERNEL, NUMA_NO_NODE, > + true, true), 0); > + > + /* > + * round_robin must hand out strictly increasing bit numbers while the > + * map fills up from empty. > + */ > + for (i = 0; i < SBITMAP_TEST_DEPTH; i++) { > + bit = sbitmap_get(&sb); > + KUNIT_ASSERT_GE(test, bit, 0); > + KUNIT_ASSERT_LT(test, bit, (int)SBITMAP_TEST_DEPTH); > + if (prev != -1) > + KUNIT_ASSERT_GT(test, bit, prev); > + prev = bit; > + } > + > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), > + (unsigned int)SBITMAP_TEST_DEPTH); > + KUNIT_EXPECT_EQ(test, sbitmap_get(&sb), -1); > + > + sbitmap_free(&sb); > +} > + > +static void sbitmap_test_resize(struct kunit *test) > +{ > + const unsigned int depth = 4 * BITS_PER_LONG; > + struct sbitmap sb; > + unsigned int i; > + > + KUNIT_ASSERT_EQ(test, sbitmap_init_node(&sb, depth, -1, GFP_KERNEL, > + NUMA_NO_NODE, true, true), 0); > + > + for (i = 0; i < depth; i++) > + KUNIT_ASSERT_GE(test, sbitmap_get(&sb), 0); > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), depth); > + > + /* Shrinking hides the bits past the new depth. */ > + sbitmap_resize(&sb, depth / 2); > + KUNIT_EXPECT_EQ(test, sb.depth, depth / 2); > + KUNIT_EXPECT_EQ(test, sb.map_nr, > + DIV_ROUND_UP(depth / 2, 1U << sb.shift)); > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), depth / 2); > + KUNIT_EXPECT_EQ(test, sbitmap_get(&sb), -1); > + > + /* Growing makes them visible again; they are still allocated. */ > + sbitmap_resize(&sb, depth); > + KUNIT_EXPECT_EQ(test, sb.depth, depth); > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), depth); > + KUNIT_EXPECT_EQ(test, sbitmap_get(&sb), -1); > + > + sbitmap_free(&sb); > +} > + > +static void sbitmap_test_set_clear_bit(struct kunit *test) > +{ > + static const unsigned int bits[] = { > + 0, 1, BITS_PER_LONG - 1, BITS_PER_LONG, > + 2 * BITS_PER_LONG + 3, SBITMAP_TEST_DEPTH - 1 > + }; > + struct sbitmap sb; > + unsigned int i; > + > + KUNIT_ASSERT_EQ(test, sbitmap_init_node(&sb, SBITMAP_TEST_DEPTH, -1, > + GFP_KERNEL, NUMA_NO_NODE, > + false, true), 0); > + > + KUNIT_EXPECT_FALSE(test, sbitmap_any_bit_set(&sb)); > + > + for (i = 0; i < ARRAY_SIZE(bits); i++) { > + sbitmap_set_bit(&sb, bits[i]); > + KUNIT_EXPECT_TRUE(test, sbitmap_test_bit(&sb, bits[i])); > + } > + KUNIT_EXPECT_TRUE(test, sbitmap_any_bit_set(&sb)); > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), (unsigned int)ARRAY_SIZE(bits)); > + > + for (i = 0; i < ARRAY_SIZE(bits); i++) { > + sbitmap_clear_bit(&sb, bits[i]); > + KUNIT_EXPECT_FALSE(test, sbitmap_test_bit(&sb, bits[i])); > + } > + KUNIT_EXPECT_FALSE(test, sbitmap_any_bit_set(&sb)); > + KUNIT_EXPECT_EQ(test, sbitmap_weight(&sb), 0U); > + > + sbitmap_free(&sb); > +} > + > +struct sbitmap_iter_ctx { > + struct kunit *test; > + DECLARE_BITMAP(visited, SBITMAP_TEST_DEPTH); > + unsigned int nr_visited; > +}; > + > +static bool sbitmap_iter_collect(struct sbitmap *sb, unsigned int bitnr, > + void *data) > +{ > + struct sbitmap_iter_ctx *ctx = data; > + > + KUNIT_ASSERT_LT(ctx->test, bitnr, SBITMAP_TEST_DEPTH); > + __set_bit(bitnr, ctx->visited); > + ctx->nr_visited++; > + > + return true; > +} > + > +static void sbitmap_test_iterate_set(struct kunit *test) > +{ > + static const unsigned int bits[] = { > + 0, 5, BITS_PER_LONG - 1, BITS_PER_LONG, 130, > + SBITMAP_TEST_DEPTH - 1 > + }; > + struct sbitmap_iter_ctx ctx = { .test = test }; > + struct sbitmap sb; > + unsigned int i; > + > + KUNIT_ASSERT_EQ(test, sbitmap_init_node(&sb, SBITMAP_TEST_DEPTH, -1, > + GFP_KERNEL, NUMA_NO_NODE, > + false, true), 0); > + > + for (i = 0; i < ARRAY_SIZE(bits); i++) > + sbitmap_set_bit(&sb, bits[i]); > + > + sbitmap_for_each_set(&sb, sbitmap_iter_collect, &ctx); > + > + KUNIT_EXPECT_EQ(test, ctx.nr_visited, (unsigned int)ARRAY_SIZE(bits)); This fails on 32-bit UML w/ gcc 16.2.1 (SUSE): nr_visited == 5, ARRAY_SIZE(bits) == 7. Seems to be passing with clang 23.1.2, though. > + for (i = 0; i < ARRAY_SIZE(bits); i++) > + KUNIT_EXPECT_TRUE(test, test_bit(bits[i], ctx.visited)); > + > + sbitmap_free(&sb); > +} > + > +static struct kunit_case sbitmap_test_cases[] = { > + KUNIT_CASE(sbitmap_test_init), > + KUNIT_CASE(sbitmap_test_calculate_shift), > + KUNIT_CASE(sbitmap_test_get_exhaust), > + KUNIT_CASE(sbitmap_test_put_reuse), > + KUNIT_CASE(sbitmap_test_round_robin), > + KUNIT_CASE(sbitmap_test_resize), > + KUNIT_CASE(sbitmap_test_set_clear_bit), > + KUNIT_CASE(sbitmap_test_iterate_set), > + {} > +}; > + > +static struct kunit_suite sbitmap_test_suite = { > + .name = "sbitmap", > + .test_cases = sbitmap_test_cases, > +}; > + > +kunit_test_suite(sbitmap_test_suite); > + > +MODULE_DESCRIPTION("KUnit test for sbitmap"); > +MODULE_LICENSE("GPL"); > > base-commit: 4056b3c9d3c92ea45955641dbafeb9b960e146ef