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[2a03:2880:20ff:7::face:b00c]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7a1d7435577sm636521785a.96.2024.07.30.05.54.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jul 2024 05:54:15 -0700 (PDT) From: Usama Arif To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, roman.gushchin@linux.dev, yuzhao@google.com, david@redhat.com, baohua@kernel.org, ryan.roberts@arm.com, rppt@kernel.org, willy@infradead.org, cerasuolodomenico@gmail.com, corbet@lwn.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@meta.com, Alexander Zhu , Usama Arif Subject: [PATCH 5/6] mm: add selftests to split_huge_page() to verify unmap/zap of zero pages Date: Tue, 30 Jul 2024 13:46:02 +0100 Message-ID: <20240730125346.1580150-6-usamaarif642@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240730125346.1580150-1-usamaarif642@gmail.com> References: <20240730125346.1580150-1-usamaarif642@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Alexander Zhu Self tests to verify the RssAnon value to make sure zero pages are not remapped except in the case of userfaultfd. Also includes a self test for the userfaultfd use case. Signed-off-by: Alexander Zhu Signed-off-by: Usama Arif Acked-by: Rik van Riel --- .../selftests/mm/split_huge_page_test.c | 113 ++++++++++++++++++ tools/testing/selftests/mm/vm_util.c | 22 ++++ tools/testing/selftests/mm/vm_util.h | 1 + 3 files changed, 136 insertions(+) diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/test= ing/selftests/mm/split_huge_page_test.c index e5e8dafc9d94..da271ad6ff11 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -17,6 +17,8 @@ #include #include #include +#include +#include #include "vm_util.h" #include "../kselftest.h" =20 @@ -84,6 +86,115 @@ static void write_debugfs(const char *fmt, ...) write_file(SPLIT_DEBUGFS, input, ret + 1); } =20 +static char *allocate_zero_filled_hugepage(size_t len) +{ + char *result; + size_t i; + + result =3D memalign(pmd_pagesize, len); + if (!result) { + printf("Fail to allocate memory\n"); + exit(EXIT_FAILURE); + } + + madvise(result, len, MADV_HUGEPAGE); + + for (i =3D 0; i < len; i++) + result[i] =3D (char)0; + + return result; +} + +static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int= nr_hpages, size_t len) +{ + uint64_t rss_anon_before, rss_anon_after; + size_t i; + + if (!check_huge_anon(one_page, 4, pmd_pagesize)) { + printf("No THP is allocated\n"); + exit(EXIT_FAILURE); + } + + rss_anon_before =3D rss_anon(); + if (!rss_anon_before) { + printf("No RssAnon is allocated before split\n"); + exit(EXIT_FAILURE); + } + + /* split all THPs */ + write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, + (uint64_t)one_page + len, 0); + + for (i =3D 0; i < len; i++) + if (one_page[i] !=3D (char)0) { + printf("%ld byte corrupted\n", i); + exit(EXIT_FAILURE); + } + + if (!check_huge_anon(one_page, 0, pmd_pagesize)) { + printf("Still AnonHugePages not split\n"); + exit(EXIT_FAILURE); + } + + rss_anon_after =3D rss_anon(); + if (rss_anon_after >=3D rss_anon_before) { + printf("Incorrect RssAnon value. Before: %ld After: %ld\n", + rss_anon_before, rss_anon_after); + exit(EXIT_FAILURE); + } +} + +void split_pmd_zero_pages(void) +{ + char *one_page; + int nr_hpages =3D 4; + size_t len =3D nr_hpages * pmd_pagesize; + + one_page =3D allocate_zero_filled_hugepage(len); + verify_rss_anon_split_huge_page_all_zeroes(one_page, nr_hpages, len); + printf("Split zero filled huge pages successful\n"); + free(one_page); +} + +void split_pmd_zero_pages_uffd(void) +{ + char *one_page; + int nr_hpages =3D 4; + size_t len =3D nr_hpages * pmd_pagesize; + long uffd; /* userfaultfd file descriptor */ + struct uffdio_api uffdio_api; + struct uffdio_register uffdio_register; + + /* Create and enable userfaultfd object. */ + + uffd =3D syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); + if (uffd =3D=3D -1) { + perror("userfaultfd"); + exit(1); + } + + uffdio_api.api =3D UFFD_API; + uffdio_api.features =3D 0; + if (ioctl(uffd, UFFDIO_API, &uffdio_api) =3D=3D -1) { + perror("ioctl-UFFDIO_API"); + exit(1); + } + + one_page =3D allocate_zero_filled_hugepage(len); + + uffdio_register.range.start =3D (unsigned long)one_page; + uffdio_register.range.len =3D len; + uffdio_register.mode =3D UFFDIO_REGISTER_MODE_WP; + if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) =3D=3D -1) { + perror("ioctl-UFFDIO_REGISTER"); + exit(1); + } + + verify_rss_anon_split_huge_page_all_zeroes(one_page, nr_hpages, len); + printf("Split zero filled huge pages with uffd successful\n"); + free(one_page); +} + void split_pmd_thp(void) { char *one_page; @@ -431,6 +542,8 @@ int main(int argc, char **argv) =20 fd_size =3D 2 * pmd_pagesize; =20 + split_pmd_zero_pages(); + split_pmd_zero_pages_uffd(); split_pmd_thp(); split_pte_mapped_thp(); split_file_backed_thp(); diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests= /mm/vm_util.c index 5a62530da3b5..7b7e763ba8e3 100644 --- a/tools/testing/selftests/mm/vm_util.c +++ b/tools/testing/selftests/mm/vm_util.c @@ -12,6 +12,7 @@ =20 #define PMD_SIZE_FILE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_= size" #define SMAP_FILE_PATH "/proc/self/smaps" +#define STATUS_FILE_PATH "/proc/self/status" #define MAX_LINE_LENGTH 500 =20 unsigned int __page_size; @@ -171,6 +172,27 @@ uint64_t read_pmd_pagesize(void) return strtoul(buf, NULL, 10); } =20 +uint64_t rss_anon(void) +{ + uint64_t rss_anon =3D 0; + FILE *fp; + char buffer[MAX_LINE_LENGTH]; + + fp =3D fopen(STATUS_FILE_PATH, "r"); + if (!fp) + ksft_exit_fail_msg("%s: Failed to open file %s\n", __func__, STATUS_FILE= _PATH); + + if (!check_for_pattern(fp, "RssAnon:", buffer, sizeof(buffer))) + goto err_out; + + if (sscanf(buffer, "RssAnon:%10ld kB", &rss_anon) !=3D 1) + ksft_exit_fail_msg("Reading status error\n"); + +err_out: + fclose(fp); + return rss_anon; +} + bool __check_huge(void *addr, char *pattern, int nr_hpages, uint64_t hpage_size) { diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests= /mm/vm_util.h index 9007c420d52c..71b75429f4a5 100644 --- a/tools/testing/selftests/mm/vm_util.h +++ b/tools/testing/selftests/mm/vm_util.h @@ -39,6 +39,7 @@ unsigned long pagemap_get_pfn(int fd, char *start); void clear_softdirty(void); bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t le= n); uint64_t read_pmd_pagesize(void); +uint64_t rss_anon(void); bool check_huge_anon(void *addr, int nr_hpages, uint64_t hpage_size); bool check_huge_file(void *addr, int nr_hpages, uint64_t hpage_size); bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size); --=20 2.43.0