From patchwork Wed Nov 16 10:26:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13044750 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A13CC43217 for ; Wed, 16 Nov 2022 10:32:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231838AbiKPKcg (ORCPT ); Wed, 16 Nov 2022 05:32:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233082AbiKPKcP (ORCPT ); Wed, 16 Nov 2022 05:32:15 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD8F332B9D for ; Wed, 16 Nov 2022 02:27:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668594466; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GX1A4FEx/LE5NKT2fU0VhMZiNOmIzFjwXIrq7S69i44=; b=B+z6baQKXmnuHiJEFeRzmLzEvcZxIIxIXZOFUjt8YiY5O+4g6ymTDm7nj4dhQ/oQnFReZ4 cgYXdWdwOapxNa/lRVpuKsskH+QYwaYVOhczwhkNsxLnbl8s93R9utvjs4CTyI6r+wHm8h xV5iwwUe6wfYkTnbOYMq1rrPKJ3tgoY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-553-e8D79onzO9-Dj-jIrITFeA-1; Wed, 16 Nov 2022 05:27:45 -0500 X-MC-Unique: e8D79onzO9-Dj-jIrITFeA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 76CF7185A792; Wed, 16 Nov 2022 10:27:38 +0000 (UTC) Received: from t480s.fritz.box (unknown [10.39.193.216]) by smtp.corp.redhat.com (Postfix) with ESMTP id 761C02024CC8; Wed, 16 Nov 2022 10:27:31 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-samsung-soc@vger.kernel.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-perf-users@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kselftest@vger.kernel.org, Linus Torvalds , Andrew Morton , Jason Gunthorpe , John Hubbard , Peter Xu , Greg Kroah-Hartman , Andrea Arcangeli , Hugh Dickins , Nadav Amit , Vlastimil Babka , Matthew Wilcox , Mike Kravetz , Muchun Song , Shuah Khan , Lucas Stach , David Airlie , Oded Gabbay , Arnd Bergmann , Christoph Hellwig , Alex Williamson , David Hildenbrand Subject: [PATCH mm-unstable v1 02/20] selftests/vm: cow: basic COW tests for non-anonymous pages Date: Wed, 16 Nov 2022 11:26:41 +0100 Message-Id: <20221116102659.70287-3-david@redhat.com> In-Reply-To: <20221116102659.70287-1-david@redhat.com> References: <20221116102659.70287-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Let's add basic tests for COW with non-anonymous pages in private mappings: write access should properly trigger COW and result in the private changes not being visible through other page mappings. Especially, add tests for: * Zeropage * Huge zeropage * Ordinary pagecache pages via memfd and tmpfile() * Hugetlb pages via memfd Fortunately, all tests pass. Signed-off-by: David Hildenbrand --- tools/testing/selftests/vm/cow.c | 338 ++++++++++++++++++++++++++++++- 1 file changed, 337 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/vm/cow.c b/tools/testing/selftests/vm/cow.c index d202bfd63585..fb07bd44529c 100644 --- a/tools/testing/selftests/vm/cow.c +++ b/tools/testing/selftests/vm/cow.c @@ -19,6 +19,7 @@ #include #include #include +#include #include "local_config.h" #ifdef LOCAL_CONFIG_HAVE_LIBURING @@ -35,6 +36,7 @@ static size_t thpsize; static int nr_hugetlbsizes; static size_t hugetlbsizes[10]; static int gup_fd; +static bool has_huge_zeropage; static void detect_thpsize(void) { @@ -64,6 +66,31 @@ static void detect_thpsize(void) close(fd); } +static void detect_huge_zeropage(void) +{ + int fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page", + O_RDONLY); + size_t enabled = 0; + char buf[15]; + int ret; + + if (fd < 0) + return; + + ret = pread(fd, buf, sizeof(buf), 0); + if (ret > 0 && ret < sizeof(buf)) { + buf[ret] = 0; + + enabled = strtoul(buf, NULL, 10); + if (enabled == 1) { + has_huge_zeropage = true; + ksft_print_msg("[INFO] huge zeropage is enabled\n"); + } + } + + close(fd); +} + static void detect_hugetlbsizes(void) { DIR *dir = opendir("/sys/kernel/mm/hugepages/"); @@ -1148,6 +1175,312 @@ static int tests_per_anon_test_case(void) return tests; } +typedef void (*non_anon_test_fn)(char *mem, const char *smem, size_t size); + +static void test_cow(char *mem, const char *smem, size_t size) +{ + char *old = malloc(size); + + /* Backup the original content. */ + memcpy(old, smem, size); + + /* Modify the page. */ + memset(mem, 0xff, size); + + /* See if we still read the old values via the other mapping. */ + ksft_test_result(!memcmp(smem, old, size), + "Other mapping not modified\n"); + free(old); +} + +static void run_with_zeropage(non_anon_test_fn fn, const char *desc) +{ + char *mem, *smem, tmp; + + ksft_print_msg("[RUN] %s ... with shared zeropage\n", desc); + + mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANON, -1, 0); + if (mem == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + return; + } + + smem = mmap(NULL, pagesize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0); + if (mem == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + goto munmap; + } + + /* Read from the page to populate the shared zeropage. */ + tmp = *mem + *smem; + asm volatile("" : "+r" (tmp)); + + fn(mem, smem, pagesize); +munmap: + munmap(mem, pagesize); + if (smem != MAP_FAILED) + munmap(smem, pagesize); +} + +static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc) +{ + char *mem, *smem, *mmap_mem, *mmap_smem, tmp; + size_t mmap_size; + int ret; + + ksft_print_msg("[RUN] %s ... with huge zeropage\n", desc); + + if (!has_huge_zeropage) { + ksft_test_result_skip("Huge zeropage not enabled\n"); + return; + } + + /* For alignment purposes, we need twice the thp size. */ + mmap_size = 2 * thpsize; + mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (mmap_mem == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + return; + } + mmap_smem = mmap(NULL, mmap_size, PROT_READ, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (mmap_smem == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + goto munmap; + } + + /* We need a THP-aligned memory area. */ + mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1)); + smem = (char *)(((uintptr_t)mmap_smem + thpsize) & ~(thpsize - 1)); + + ret = madvise(mem, thpsize, MADV_HUGEPAGE); + ret |= madvise(smem, thpsize, MADV_HUGEPAGE); + if (ret) { + ksft_test_result_fail("MADV_HUGEPAGE failed\n"); + goto munmap; + } + + /* + * Read from the memory to populate the huge shared zeropage. Read from + * the first sub-page and test if we get another sub-page populated + * automatically. + */ + tmp = *mem + *smem; + asm volatile("" : "+r" (tmp)); + if (!pagemap_is_populated(pagemap_fd, mem + pagesize) || + !pagemap_is_populated(pagemap_fd, smem + pagesize)) { + ksft_test_result_skip("Did not get THPs populated\n"); + goto munmap; + } + + fn(mem, smem, thpsize); +munmap: + munmap(mmap_mem, mmap_size); + if (mmap_smem != MAP_FAILED) + munmap(mmap_smem, mmap_size); +} + +static void run_with_memfd(non_anon_test_fn fn, const char *desc) +{ + char *mem, *smem, tmp; + int fd; + + ksft_print_msg("[RUN] %s ... with memfd\n", desc); + + fd = memfd_create("test", 0); + if (fd < 0) { + ksft_test_result_fail("memfd_create() failed\n"); + return; + } + + /* File consists of a single page filled with zeroes. */ + if (fallocate(fd, 0, 0, pagesize)) { + ksft_test_result_fail("fallocate() failed\n"); + goto close; + } + + /* Create a private mapping of the memfd. */ + mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); + if (mem == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + goto close; + } + smem = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, fd, 0); + if (mem == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + goto munmap; + } + + /* Fault the page in. */ + tmp = *mem + *smem; + asm volatile("" : "+r" (tmp)); + + fn(mem, smem, pagesize); +munmap: + munmap(mem, pagesize); + if (smem != MAP_FAILED) + munmap(smem, pagesize); +close: + close(fd); +} + +static void run_with_tmpfile(non_anon_test_fn fn, const char *desc) +{ + char *mem, *smem, tmp; + FILE *file; + int fd; + + ksft_print_msg("[RUN] %s ... with tmpfile\n", desc); + + file = tmpfile(); + if (!file) { + ksft_test_result_fail("tmpfile() failed\n"); + return; + } + + fd = fileno(file); + if (fd < 0) { + ksft_test_result_skip("fileno() failed\n"); + return; + } + + /* File consists of a single page filled with zeroes. */ + if (fallocate(fd, 0, 0, pagesize)) { + ksft_test_result_fail("fallocate() failed\n"); + goto close; + } + + /* Create a private mapping of the memfd. */ + mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); + if (mem == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + goto close; + } + smem = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, fd, 0); + if (mem == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + goto munmap; + } + + /* Fault the page in. */ + tmp = *mem + *smem; + asm volatile("" : "+r" (tmp)); + + fn(mem, smem, pagesize); +munmap: + munmap(mem, pagesize); + if (smem != MAP_FAILED) + munmap(smem, pagesize); +close: + fclose(file); +} + +static void run_with_memfd_hugetlb(non_anon_test_fn fn, const char *desc, + size_t hugetlbsize) +{ + int flags = MFD_HUGETLB; + char *mem, *smem, tmp; + int fd; + + ksft_print_msg("[RUN] %s ... with memfd hugetlb (%zu kB)\n", desc, + hugetlbsize / 1024); + + flags |= __builtin_ctzll(hugetlbsize) << MFD_HUGE_SHIFT; + + fd = memfd_create("test", flags); + if (fd < 0) { + ksft_test_result_skip("memfd_create() failed\n"); + return; + } + + /* File consists of a single page filled with zeroes. */ + if (fallocate(fd, 0, 0, hugetlbsize)) { + ksft_test_result_skip("need more free huge pages\n"); + goto close; + } + + /* Create a private mapping of the memfd. */ + mem = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, + 0); + if (mem == MAP_FAILED) { + ksft_test_result_skip("need more free huge pages\n"); + goto close; + } + smem = mmap(NULL, hugetlbsize, PROT_READ, MAP_SHARED, fd, 0); + if (mem == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + goto munmap; + } + + /* Fault the page in. */ + tmp = *mem + *smem; + asm volatile("" : "+r" (tmp)); + + fn(mem, smem, hugetlbsize); +munmap: + munmap(mem, hugetlbsize); + if (mem != MAP_FAILED) + munmap(smem, hugetlbsize); +close: + close(fd); +} + +struct non_anon_test_case { + const char *desc; + non_anon_test_fn fn; +}; + +/* + * Test cases that target any pages in private mappings that are non anonymous: + * pages that may get shared via COW ndependent of fork(). This includes + * the shared zeropage(s), pagecache pages, ... + */ +static const struct non_anon_test_case non_anon_test_cases[] = { + /* + * Basic COW test without any GUP. If we miss to break COW, changes are + * visible via other private/shared mappings. + */ + { + "Basic COW", + test_cow, + }, +}; + +static void run_non_anon_test_case(struct non_anon_test_case const *test_case) +{ + int i; + + run_with_zeropage(test_case->fn, test_case->desc); + run_with_memfd(test_case->fn, test_case->desc); + run_with_tmpfile(test_case->fn, test_case->desc); + if (thpsize) + run_with_huge_zeropage(test_case->fn, test_case->desc); + for (i = 0; i < nr_hugetlbsizes; i++) + run_with_memfd_hugetlb(test_case->fn, test_case->desc, + hugetlbsizes[i]); +} + +static void run_non_anon_test_cases(void) +{ + int i; + + ksft_print_msg("[RUN] Non-anonymous memory tests in private mappings\n"); + + for (i = 0; i < ARRAY_SIZE(non_anon_test_cases); i++) + run_non_anon_test_case(&non_anon_test_cases[i]); +} + +static int tests_per_non_anon_test_case(void) +{ + int tests = 3 + nr_hugetlbsizes; + + if (thpsize) + tests += 1; + return tests; +} + int main(int argc, char **argv) { int err; @@ -1155,9 +1488,11 @@ int main(int argc, char **argv) pagesize = getpagesize(); detect_thpsize(); detect_hugetlbsizes(); + detect_huge_zeropage(); ksft_print_header(); - ksft_set_plan(ARRAY_SIZE(anon_test_cases) * tests_per_anon_test_case()); + ksft_set_plan(ARRAY_SIZE(anon_test_cases) * tests_per_anon_test_case() + + ARRAY_SIZE(non_anon_test_cases) * tests_per_non_anon_test_case()); gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR); pagemap_fd = open("/proc/self/pagemap", O_RDONLY); @@ -1165,6 +1500,7 @@ int main(int argc, char **argv) ksft_exit_fail_msg("opening pagemap failed\n"); run_anon_test_cases(); + run_non_anon_test_cases(); err = ksft_get_fail_cnt(); if (err)