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Thu, 16 Apr 2026 23:53:34 -0700 (PDT) Received: from localhost ([2a07:de40:b240:0:2ad6:ed42:2ad6:ed42]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-43fe4cb1176sm2254141f8f.3.2026.04.16.23.53.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Apr 2026 23:53:34 -0700 (PDT) To: ltp@lists.linux.it Date: Fri, 17 Apr 2026 06:53:25 +0000 Message-ID: <20260417065332.23663-1-wegao@suse.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260410023201.18119-1-wegao@suse.com> References: <20260410023201.18119-1-wegao@suse.com> MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 1.0.9 at in-4.smtp.seeweb.it X-Virus-Status: Clean Subject: [LTP] [PATCH v7] mremap07.c: New test for mremap() with MREMAP_DONTUNMAP X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Wei Gao via ltp Reply-To: Wei Gao Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" This test verifies the mremap() syscall with the MREMAP_DONTUNMAP flag. It uses userfaultfd to verify that accessing the old memory region correctly triggers a page fault after the mapping has been moved. MREMAP_DONTUNMAP behavior with userfaultfd was not covered by existing mremap tests. This test provides coverage for the feature requested in the linked issue. Fixes: https://github.com/linux-test-project/ltp/issues/1168 Signed-off-by: Wei Gao --- v6->v7: - Update commit description - Update year of copyright configure.ac | 1 + runtest/syscalls | 1 + testcases/kernel/syscalls/mremap/.gitignore | 1 + testcases/kernel/syscalls/mremap/Makefile | 1 + testcases/kernel/syscalls/mremap/mremap07.c | 158 ++++++++++++++++++++ 5 files changed, 162 insertions(+) create mode 100644 testcases/kernel/syscalls/mremap/mremap07.c diff --git a/configure.ac b/configure.ac index 812f17d8b..211aaa8ad 100644 --- a/configure.ac +++ b/configure.ac @@ -46,6 +46,7 @@ AC_CHECK_DECLS([MADV_MERGEABLE],,,[#include ]) AC_CHECK_DECLS([NFTA_CHAIN_ID, NFTA_VERDICT_CHAIN_ID],,,[#include ]) AC_CHECK_DECLS([PR_CAPBSET_DROP, PR_CAPBSET_READ],,,[#include ]) AC_CHECK_DECLS([SEM_STAT_ANY],,,[#include ]) +AC_CHECK_DECLS([MREMAP_DONTUNMAP],,,[#include ]) AC_CHECK_HEADERS_ONCE([ \ aio.h \ diff --git a/runtest/syscalls b/runtest/syscalls index d72fceb5e..b9a9ce5fe 100644 --- a/runtest/syscalls +++ b/runtest/syscalls @@ -927,6 +927,7 @@ mremap03 mremap03 mremap04 mremap04 mremap05 mremap05 mremap06 mremap06 +mremap07 mremap07 mseal01 mseal01 mseal02 mseal02 diff --git a/testcases/kernel/syscalls/mremap/.gitignore b/testcases/kernel/syscalls/mremap/.gitignore index ec15a19cd..292899e03 100644 --- a/testcases/kernel/syscalls/mremap/.gitignore +++ b/testcases/kernel/syscalls/mremap/.gitignore @@ -4,3 +4,4 @@ /mremap04 /mremap05 /mremap06 +/mremap07 diff --git a/testcases/kernel/syscalls/mremap/Makefile b/testcases/kernel/syscalls/mremap/Makefile index 9f5aca9ec..8811b887e 100644 --- a/testcases/kernel/syscalls/mremap/Makefile +++ b/testcases/kernel/syscalls/mremap/Makefile @@ -8,5 +8,6 @@ LTPLIBS = ipc include $(top_srcdir)/include/mk/testcases.mk mremap04: LTPLDLIBS = -lltpipc +mremap07: LDLIBS += -lpthread include $(top_srcdir)/include/mk/generic_leaf_target.mk diff --git a/testcases/kernel/syscalls/mremap/mremap07.c b/testcases/kernel/syscalls/mremap/mremap07.c new file mode 100644 index 000000000..102136322 --- /dev/null +++ b/testcases/kernel/syscalls/mremap/mremap07.c @@ -0,0 +1,158 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2026 Wei Gao + */ + +/*\ + * LTP test case for mremap() with MREMAP_DONTUNMAP and userfaultfd. + * + * Test mremap() with MREMAP_DONTUNMAP and verify that accessing the + * old memory region triggers a page fault, which is then correctly + * handled by a userfaultfd handler. + */ + +#define _GNU_SOURCE +#include +#include +#include + +#include "tst_test.h" +#include "tst_safe_pthread.h" +#include "lapi/userfaultfd.h" +#include "config.h" + +#if HAVE_DECL_MREMAP_DONTUNMAP + +static int page_size; +static int uffd = -1; +static char *fault_addr; +static char *new_remap_addr; + +static const char *test_string = "Hello, world! This is a test string that fills up a page."; + +static void *fault_handler_thread(void *arg LTP_ATTRIBUTE_UNUSED) +{ + struct uffd_msg msg; + struct uffdio_copy uffdio_copy; + + TST_CHECKPOINT_WAIT(0); + + struct pollfd pollfd; + + pollfd.fd = uffd; + pollfd.events = POLLIN; + + int nready = poll(&pollfd, 1, -1); + + if (nready == -1) + tst_brk(TBROK | TERRNO, "poll() failed"); + + if (nready == 0) + tst_brk(TBROK, "poll() timed out unexpectedly"); + + SAFE_READ(1, uffd, &msg, sizeof(msg)); + + if (msg.event != UFFD_EVENT_PAGEFAULT) + tst_brk(TBROK, "Received unexpected UFFD_EVENT: %d", msg.event); + + if ((char *)msg.arg.pagefault.address != fault_addr) + tst_brk(TBROK, "Page fault on unexpected address: %p", (void *)msg.arg.pagefault.address); + + tst_res(TINFO, "Userfaultfd handler caught a page fault at %p", (void *)msg.arg.pagefault.address); + + uffdio_copy.src = (unsigned long)new_remap_addr; + uffdio_copy.dst = (unsigned long)fault_addr; + uffdio_copy.len = page_size; + uffdio_copy.mode = 0; + uffdio_copy.copy = 0; + + SAFE_IOCTL(uffd, UFFDIO_COPY, &uffdio_copy); + tst_res(TPASS, "Userfaultfd handler successfully handled the fault"); + + return NULL; +} + +static void setup(void) +{ + page_size = getpagesize(); + struct uffdio_api uffdio_api; + struct uffdio_register uffdio_register; + + uffd = SAFE_USERFAULTFD(O_CLOEXEC | O_NONBLOCK, true); + + uffdio_api.api = UFFD_API; + uffdio_api.features = 0; + SAFE_IOCTL(uffd, UFFDIO_API, &uffdio_api); + + fault_addr = SAFE_MMAP(NULL, page_size, + PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + + tst_res(TINFO, "Original mapping created at %p", (void *)fault_addr); + + strcpy(fault_addr, "ABCD"); + + uffdio_register.range.start = (unsigned long)fault_addr; + uffdio_register.range.len = page_size; + uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING; + SAFE_IOCTL(uffd, UFFDIO_REGISTER, &uffdio_register); +} + +static void cleanup(void) +{ + if (new_remap_addr && new_remap_addr != MAP_FAILED) + SAFE_MUNMAP(new_remap_addr, page_size); + + if (fault_addr && fault_addr != MAP_FAILED) + SAFE_MUNMAP(fault_addr, page_size); + + if (uffd != -1) + SAFE_CLOSE(uffd); +} + +static void run(void) +{ + pthread_t handler_thread; + + SAFE_PTHREAD_CREATE(&handler_thread, NULL, + fault_handler_thread, NULL); + + new_remap_addr = mremap(fault_addr, page_size, page_size, + MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL); + + if (new_remap_addr == MAP_FAILED) + tst_brk(TBROK | TERRNO, "mremap failed"); + + tst_res(TINFO, "New mapping created at %p", (void *)new_remap_addr); + + strcpy(new_remap_addr, test_string); + + TST_CHECKPOINT_WAKE(0); + + tst_res(TINFO, "Main thread accessing old address %p to trigger fault", + (void *)fault_addr); + + (void)*(volatile char *)fault_addr; + + SAFE_PTHREAD_JOIN(handler_thread, NULL); + + TST_EXP_EQ_STR(fault_addr, test_string); + + SAFE_MUNMAP(new_remap_addr, page_size); + new_remap_addr = NULL; +} + +static struct tst_test test = { + .test_all = run, + .setup = setup, + .needs_checkpoints = 1, + .cleanup = cleanup, + .needs_kconfigs = (const char *[]) { + "CONFIG_USERFAULTFD=y", + NULL, + }, + .min_kver = "5.7", +}; + +#else +TST_TEST_TCONF("Missing MREMAP_DONTUNMAP in "); +#endif -- 2.52.0 -- Mailing list info: https://lists.linux.it/listinfo/ltp