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[184.145.104.227]) by smtp.gmail.com with ESMTPSA id 191sm897459qkk.31.2021.04.28.15.51.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Apr 2021 15:51:23 -0700 (PDT) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Mike Kravetz , peterx@redhat.com, Mike Rapoport , Axel Rasmussen , Andrea Arcangeli , Hugh Dickins , "Kirill A . Shutemov" , Andrew Morton , Jerome Glisse Subject: [PATCH 6/6] userfaultfd/selftests: Add pagemap uffd-wp test Date: Wed, 28 Apr 2021 18:50:30 -0400 Message-Id: <20210428225030.9708-7-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210428225030.9708-1-peterx@redhat.com> References: <20210428225030.9708-1-peterx@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: C94AEA0003A2 X-Stat-Signature: rqbt4hsizk7rzfemx4ny5zsrpi6nxw9h Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf23; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619650282-894602 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Add one anonymous specific test to start using pagemap. With pagemap support, we can directly read the uffd-wp bit from pgtable without triggering any fault, so it's easier to do sanity checks in unit tests. Meanwhile this test also leverages the newly introduced MADV_PAGEOUT madvise function to test swap ptes with uffd-wp bit set, and across fork()s. Signed-off-by: Peter Xu --- tools/testing/selftests/vm/userfaultfd.c | 154 +++++++++++++++++++++++ 1 file changed, 154 insertions(+) diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index 6339aeaeeff8b..93eae095b61e6 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -1170,6 +1170,144 @@ static int userfaultfd_minor_test(void) return stats.missing_faults != 0 || stats.minor_faults != nr_pages; } +#define BIT_ULL(nr) (1ULL << (nr)) +#define PM_SOFT_DIRTY BIT_ULL(55) +#define PM_MMAP_EXCLUSIVE BIT_ULL(56) +#define PM_UFFD_WP BIT_ULL(57) +#define PM_FILE BIT_ULL(61) +#define PM_SWAP BIT_ULL(62) +#define PM_PRESENT BIT_ULL(63) + +static int pagemap_open(void) +{ + int fd = open("/proc/self/pagemap", O_RDONLY); + + if (fd < 0) + err("open pagemap"); + + return fd; +} + +static uint64_t pagemap_read_vaddr(int fd, void *vaddr) +{ + uint64_t value; + int ret; + + ret = pread(fd, &value, sizeof(uint64_t), + ((uint64_t)vaddr >> 12) * sizeof(uint64_t)); + if (ret != sizeof(uint64_t)) + err("pread() on pagemap failed"); + + return value; +} + +/* This macro let __LINE__ works in err() */ +#define pagemap_check_wp(value, wp) do { \ + if (!!(value & PM_UFFD_WP) != wp) \ + err("pagemap uffd-wp bit error: 0x%"PRIx64, value); \ + } while (0) + +static int pagemap_test_fork(bool present) +{ + pid_t child = fork(); + uint64_t value; + int fd, result; + + if (!child) { + /* Open the pagemap fd of the child itself */ + fd = pagemap_open(); + value = pagemap_read_vaddr(fd, area_dst); + /* + * After fork() uffd-wp bit should be gone as long as we're + * without UFFD_FEATURE_EVENT_FORK + */ + pagemap_check_wp(value, false); + /* Succeed */ + exit(0); + } + waitpid(child, &result, 0); + return result; +} + +static void userfaultfd_pagemap_test(unsigned int test_pgsize) +{ + struct uffdio_register uffdio_register; + int pagemap_fd; + uint64_t value; + + /* Pagemap tests uffd-wp only */ + if (!test_uffdio_wp) + return; + + /* Not enough memory to test this page size */ + if (test_pgsize > nr_pages * page_size) + return; + + printf("testing uffd-wp with pagemap (pgsize=%u): ", test_pgsize); + /* Flush so it doesn't flush twice in parent/child later */ + fflush(stdout); + + uffd_test_ops->release_pages(area_dst); + + if (test_pgsize > page_size) { + /* This is a thp test */ + if (madvise(area_dst, nr_pages * page_size, MADV_HUGEPAGE)) + err("madvise(MADV_HUGEPAGE) failed"); + } else if (test_pgsize == page_size) { + /* This is normal page test; force no thp */ + if (madvise(area_dst, nr_pages * page_size, MADV_NOHUGEPAGE)) + err("madvise(MADV_NOHUGEPAGE) failed"); + } + + if (userfaultfd_open(0)) + err("userfaultfd_open"); + + uffdio_register.range.start = (unsigned long) area_dst; + uffdio_register.range.len = nr_pages * page_size; + uffdio_register.mode = UFFDIO_REGISTER_MODE_WP; + if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register)) + err("register failed"); + + pagemap_fd = pagemap_open(); + + /* Touch the page */ + *area_dst = 1; + wp_range(uffd, (uint64_t)area_dst, test_pgsize, true); + value = pagemap_read_vaddr(pagemap_fd, area_dst); + pagemap_check_wp(value, true); + /* Make sure uffd-wp bit dropped when fork */ + if (pagemap_test_fork(true)) + err("Detected stall uffd-wp bit in child"); + + /* Exclusive required or PAGEOUT won't work */ + if (!(value & PM_MMAP_EXCLUSIVE)) + err("multiple mapping detected: 0x%"PRIx64, value); + + if (madvise(area_dst, test_pgsize, MADV_PAGEOUT)) + err("madvise(MADV_PAGEOUT) failed"); + + /* Uffd-wp should persist even swapped out */ + value = pagemap_read_vaddr(pagemap_fd, area_dst); + pagemap_check_wp(value, true); + /* Make sure uffd-wp bit dropped when fork */ + if (pagemap_test_fork(false)) + err("Detected stall uffd-wp bit in child"); + + /* Unprotect; this tests swap pte modifications */ + wp_range(uffd, (uint64_t)area_dst, page_size, false); + value = pagemap_read_vaddr(pagemap_fd, area_dst); + pagemap_check_wp(value, false); + + /* Fault in the page from disk */ + *area_dst = 2; + value = pagemap_read_vaddr(pagemap_fd, area_dst); + pagemap_check_wp(value, false); + + close(pagemap_fd); + close(uffd); + printf("done\n"); +} + static int userfaultfd_stress(void) { void *area; @@ -1341,6 +1479,22 @@ static int userfaultfd_stress(void) } close(uffd); + + if (test_type == TEST_ANON) { + /* + * shmem/hugetlb won't be able to run since they have different + * behavior on fork() (file-backed memory normally drops ptes + * directly when fork), meanwhile the pagemap test will verify + * pgtable entry of fork()ed child. + */ + userfaultfd_pagemap_test(page_size); + /* + * Hard-code for x86_64 for now for 2M THP, as x86_64 is + * currently the only one that supports uffd-wp + */ + userfaultfd_pagemap_test(page_size * 512); + } + return userfaultfd_zeropage_test() || userfaultfd_sig_test() || userfaultfd_events_test() || userfaultfd_minor_test(); }