Date: Mon, 2 Oct 2023 12:56:03 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 98504b647138 - stable/14 - mlock tests: Add a regression test Message-ID: <202310021256.392Cu3rH036025@gitrepo.freebsd.org>
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The branch stable/14 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=98504b647138897f9c171b6e6d348c4f7bdb3a0d commit 98504b647138897f9c171b6e6d348c4f7bdb3a0d Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2023-09-15 16:28:42 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2023-10-02 12:55:49 +0000 mlock tests: Add a regression test The test tries to trigger creation of a superpage mapping in an mlock()ed region. MFC after: 2 weeks (cherry picked from commit 8f26ed01bd74aab21309ac04ae1d1368a6346c90) --- tests/sys/vm/mlock_test.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+) diff --git a/tests/sys/vm/mlock_test.c b/tests/sys/vm/mlock_test.c index f0c76fe86b56..8c8ce4a2e8de 100644 --- a/tests/sys/vm/mlock_test.c +++ b/tests/sys/vm/mlock_test.c @@ -28,11 +28,15 @@ #include <sys/cdefs.h> #include <sys/mman.h> #include <sys/ptrace.h> +#include <sys/resource.h> #include <sys/wait.h> #include <errno.h> +#include <fcntl.h> #include <signal.h> +#include <stdatomic.h> #include <stdio.h> +#include <stdlib.h> #include <string.h> #include <unistd.h> @@ -161,12 +165,122 @@ ATF_TC_BODY(mlock__truncate_and_unlock, tc) ATF_REQUIRE(munlock(addr, len) == 0); } +/* + * Exercise a corner case involving an interaction between mlock() and superpage + * creation: a truncation of the object backing a mapping results in the + * truncated region being unmapped by the pmap, but does not affect the logical + * mapping. In particular, the truncated region remains mlock()ed. If the + * mapping is later extended, a page fault in the formerly truncated region can + * result in superpage creation via a call to pmap_enter(psind = 1). + */ +ATF_TC(mlock__superpage_fault); +ATF_TC_HEAD(mlock__superpage_fault, tc) +{ + atf_tc_set_md_var(tc, "require.user", "root"); +} +ATF_TC_BODY(mlock__superpage_fault, tc) +{ + struct rlimit rlim; + void *addr1, *addr2; + size_t len, pagesizes[MAXPAGESIZES]; + int count, error, shmfd; + char vec; + + count = getpagesizes(pagesizes, MAXPAGESIZES); + ATF_REQUIRE_MSG(count >= 1, + "failed to get page sizes: %s", strerror(errno)); + if (count == 1) + atf_tc_skip("system does not support multiple page sizes"); + len = pagesizes[1]; + + error = getrlimit(RLIMIT_MEMLOCK, &rlim); + ATF_REQUIRE_MSG(error == 0, "getrlimit: %s", strerror(errno)); + rlim.rlim_cur += len; + rlim.rlim_max += len; + error = setrlimit(RLIMIT_MEMLOCK, &rlim); + ATF_REQUIRE_MSG(error == 0, "setrlimit: %s", strerror(errno)); + + shmfd = shm_open(SHM_ANON, O_RDWR | O_CREAT, 0600); + ATF_REQUIRE_MSG(shmfd >= 0, "shm_open: %s", strerror(errno)); + error = ftruncate(shmfd, len); + ATF_REQUIRE_MSG(error == 0, "ftruncate: %s", strerror(errno)); + + addr1 = mmap(NULL, len, PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ALIGNED_SUPER, shmfd, 0); + ATF_REQUIRE_MSG(addr1 != MAP_FAILED, "mmap: %s", strerror(errno)); + ATF_REQUIRE_MSG(((uintptr_t)addr1 & (len - 1)) == 0, + "addr %p is misaligned", addr1); + addr2 = mmap(NULL, len, PROT_READ, + MAP_SHARED | MAP_ALIGNED_SUPER, shmfd, 0); + ATF_REQUIRE_MSG(addr2 != MAP_FAILED, "mmap: %s", strerror(errno)); + ATF_REQUIRE_MSG(((uintptr_t)addr2 & (len - 1)) == 0, + "addr %p is misaligned", addr2); + + memset(addr1, 0x42, len); + error = mincore(addr1, pagesizes[0], &vec); + ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno)); + if ((vec & MINCORE_SUPER) == 0) + atf_tc_skip("initial superpage promotion failed"); + + error = mlock(addr2, len); + ATF_REQUIRE_MSG(error == 0, "mlock: %s", strerror(errno)); + error = mincore(addr2, pagesizes[0], &vec); + ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno)); + ATF_REQUIRE((vec & MINCORE_SUPER) != 0); + + /* + * Free a page back to the superpage reservation, demoting both + * mappings. + */ + error = ftruncate(shmfd, len - pagesizes[0]); + ATF_REQUIRE_MSG(error == 0, "ftruncate: %s", strerror(errno)); + + /* + * Extend the mapping back to its original size. + */ + error = ftruncate(shmfd, len); + ATF_REQUIRE_MSG(error == 0, "ftruncate: %s", strerror(errno)); + + /* + * Trigger re-promotion. + */ + error = mincore(addr1, pagesizes[0], &vec); + ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno)); + ATF_REQUIRE((vec & MINCORE_SUPER) == 0); + memset((char *)addr1 + len - pagesizes[0], 0x43, pagesizes[0]); + error = mincore(addr1, pagesizes[0], &vec); + ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno)); + ATF_REQUIRE((vec & MINCORE_SUPER) != 0); + + /* + * Trigger a read fault, which should install a superpage mapping + * without promotion. + */ + error = mincore(addr2, pagesizes[0], &vec); + ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno)); + ATF_REQUIRE((vec & MINCORE_SUPER) == 0); + (void)atomic_load( + (_Atomic int *)(void *)((char *)addr2 + len - pagesizes[0])); + error = mincore(addr2, pagesizes[0], &vec); + ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno)); + ATF_REQUIRE((vec & MINCORE_SUPER) != 0); + + /* + * Trigger demotion of the wired mapping. + */ + error = munlock(addr2, pagesizes[0]); + ATF_REQUIRE_MSG(error == 0, "munlock: %s", strerror(errno)); + + ATF_REQUIRE(close(shmfd) == 0); +} + ATF_TP_ADD_TCS(tp) { ATF_TP_ADD_TC(tp, mlock__copy_on_write_anon); ATF_TP_ADD_TC(tp, mlock__copy_on_write_vnode); ATF_TP_ADD_TC(tp, mlock__truncate_and_resize); ATF_TP_ADD_TC(tp, mlock__truncate_and_unlock); + ATF_TP_ADD_TC(tp, mlock__superpage_fault); return (atf_no_error()); }
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