When mapping a larger chunk than physical memory is available with PROT_WRITE and overcommit is disabled, the mapping will fail. This will prevent the test from running on systems with less then ~1GiB of memory and triggering an inscrutinable test failure. As the mappings are never written to anyways, the flag can be removed.

Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()") Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Acked-by: David Hildenbrand david@redhat.com Acked-by: Dev Jain dev.jain@arm.com --- tools/testing/selftests/mm/virtual_address_range.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c index 2a2b69e91950a37999f606847c9c8328d79890c2..ea6ccf49ef4c552f26317c2a40b09bca1a677f8f 100644 --- a/tools/testing/selftests/mm/virtual_address_range.c +++ b/tools/testing/selftests/mm/virtual_address_range.c @@ -166,7 +166,7 @@ int main(int argc, char *argv[]) ksft_set_plan(1);

for (i = 0; i < NR_CHUNKS_LOW; i++) { - ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE, + ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

if (ptr[i] == MAP_FAILED) { @@ -186,7 +186,7 @@ int main(int argc, char *argv[])

for (i = 0; i < NR_CHUNKS_HIGH; i++) { hint = hint_addr(); - hptr[i] = mmap(hint, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE, + hptr[i] = mmap(hint, MAP_CHUNK_SIZE, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

if (hptr[i] == MAP_FAILED)

For each accessed chunk a PTE is created. More than 1GiB of PTEs is used in this way. Remove each PTE after validating a chunk to reduce peak memory usage.

It is important to only unmap memory that previously mmap()ed, as unmapping other mappings like the stack, heap or executable mappings will crash the process. The mappings read from /proc/self/maps and the return values from mmap() don't allow a simple correlation due to merging and no guaranteed order. To correlate the pointers and mappings use prctl(PR_SET_VMA_ANON_NAME). While it introduces a test dependency, other alternatives would introduce runtime or development overhead.

Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()") Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de --- tools/testing/selftests/mm/config | 1 + tools/testing/selftests/mm/virtual_address_range.c | 33 ++++++++++++++++++++-- 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/config b/tools/testing/selftests/mm/config index 4309916f629e36498efb07eb606b2f0c49ee6211..a28baa536332f3fcfb1b83759b5fbb432ae80178 100644 --- a/tools/testing/selftests/mm/config +++ b/tools/testing/selftests/mm/config @@ -7,3 +7,4 @@ CONFIG_TEST_HMM=m CONFIG_GUP_TEST=y CONFIG_TRANSPARENT_HUGEPAGE=y CONFIG_MEM_SOFT_DIRTY=y +CONFIG_ANON_VMA_NAME=y diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c index ea6ccf49ef4c552f26317c2a40b09bca1a677f8f..386e4e46fa65b98af78dee4bb30144eb2b51f528 100644 --- a/tools/testing/selftests/mm/virtual_address_range.c +++ b/tools/testing/selftests/mm/virtual_address_range.c @@ -10,6 +10,7 @@ #include <string.h> #include <unistd.h> #include <errno.h> +#include <sys/prctl.h> #include <sys/mman.h> #include <sys/time.h> #include <fcntl.h> @@ -82,6 +83,24 @@ static void validate_addr(char *ptr, int high_addr) ksft_exit_fail_msg("Bad address %lx\n", addr); }

+static void mark_range(char *ptr, size_t size) +{ + if (prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, size, "virtual_address_range") == -1) { + if (errno == EINVAL) { + /* Depends on CONFIG_ANON_VMA_NAME */ + ksft_test_result_skip("prctl(PR_SET_VMA_ANON_NAME) not supported\n"); + ksft_finished(); + } else { + ksft_exit_fail_perror("prctl(PR_SET_VMA_ANON_NAME) failed\n"); + } + } +} + +static int is_marked_vma(const char *vma_name) +{ + return vma_name && !strcmp(vma_name, "[anon:virtual_address_range]\n"); +} + static int validate_lower_address_hint(void) { char *ptr; @@ -116,12 +135,17 @@ static int validate_complete_va_space(void)

prev_end_addr = 0; while (fgets(line, sizeof(line), file)) { + const char *vma_name = NULL; + int vma_name_start = 0; unsigned long hop;

- if (sscanf(line, "%lx-%lx %s[rwxp-]", - &start_addr, &end_addr, prot) != 3) + if (sscanf(line, "%lx-%lx %4s %*s %*s %*s %n", + &start_addr, &end_addr, prot, &vma_name_start) != 3) ksft_exit_fail_msg("cannot parse /proc/self/maps\n");

+ if (vma_name_start) + vma_name = line + vma_name_start; + /* end of userspace mappings; ignore vsyscall mapping */ if (start_addr & (1UL << 63)) return 0; @@ -149,6 +173,9 @@ static int validate_complete_va_space(void) return 1; lseek(fd, 0, SEEK_SET);

+ if (is_marked_vma(vma_name)) + munmap((char *)(start_addr + hop), MAP_CHUNK_SIZE); + hop += MAP_CHUNK_SIZE; } } @@ -175,6 +202,7 @@ int main(int argc, char *argv[]) break; }

+ mark_range(ptr[i], MAP_CHUNK_SIZE); validate_addr(ptr[i], 0); } lchunks = i; @@ -192,6 +220,7 @@ int main(int argc, char *argv[]) if (hptr[i] == MAP_FAILED) break;

+ mark_range(ptr[i], MAP_CHUNK_SIZE); validate_addr(hptr[i], 1); } hchunks = i;

Upcoming changes want to reuse the /proc/self/smaps parsing logic to parse the VmFlags field. As that works differently from the currently parsed HugePage counters, split up the logic so common functionality can be shared.

While reworking this code, also use the correct sscanf placeholder for the "uint64_t thp" variable.

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de --- tools/testing/selftests/mm/vm_util.c | 42 +++++++++++++++++++++++++----------- 1 file changed, 29 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c index d8d0cf04bb57fd22bd7748fffec6a23c3103e35c..8468a19d6acca10c7e9228c03a935cdeb2402b5d 100644 --- a/tools/testing/selftests/mm/vm_util.c +++ b/tools/testing/selftests/mm/vm_util.c @@ -2,6 +2,7 @@ #include <string.h> #include <fcntl.h> #include <dirent.h> +#include <inttypes.h> #include <sys/ioctl.h> #include <linux/userfaultfd.h> #include <linux/fs.h> @@ -193,13 +194,11 @@ unsigned long rss_anon(void) return rss_anon; }

-bool __check_huge(void *addr, char *pattern, int nr_hpages, - uint64_t hpage_size) +char *__get_smap_entry(void *addr, const char *pattern, char *buf, size_t len) { - uint64_t thp = -1; int ret; FILE *fp; - char buffer[MAX_LINE_LENGTH]; + char *entry; char addr_pattern[MAX_LINE_LENGTH];

ret = snprintf(addr_pattern, MAX_LINE_LENGTH, "%08lx-", @@ -211,23 +210,40 @@ bool __check_huge(void *addr, char *pattern, int nr_hpages, if (!fp) ksft_exit_fail_msg("%s: Failed to open file %s\n", __func__, SMAP_FILE_PATH);

- if (!check_for_pattern(fp, addr_pattern, buffer, sizeof(buffer))) + if (!check_for_pattern(fp, addr_pattern, buf, len)) goto err_out;

- /* - * Fetch the pattern in the same block and check the number of - * hugepages. - */ - if (!check_for_pattern(fp, pattern, buffer, sizeof(buffer))) + /* Fetch the pattern in the same block */ + if (!check_for_pattern(fp, pattern, buf, len)) goto err_out;

- snprintf(addr_pattern, MAX_LINE_LENGTH, "%s%%9ld kB", pattern); + /* Trim trailing newline */ + entry = strchr(buf, '\n'); + if (entry) + *entry = '\0';

- if (sscanf(buffer, addr_pattern, &thp) != 1) - ksft_exit_fail_msg("Reading smap error\n"); + entry = buf + strlen(pattern);

err_out: fclose(fp); + return entry; +} + +bool __check_huge(void *addr, char *pattern, int nr_hpages, + uint64_t hpage_size) +{ + char buffer[MAX_LINE_LENGTH]; + uint64_t thp = -1; + char *entry; + + entry = __get_smap_entry(addr, pattern, buffer, sizeof(buffer)); + if (!entry) + goto err_out; + + if (sscanf(entry, "%9" SCNu64 " kB", &thp) != 1) + ksft_exit_fail_msg("Reading smap error\n"); + +err_out: return thp == (nr_hpages * (hpage_size >> 10)); }

The virtual_address_range selftest reads from the start of each mapping listed in /proc/self/maps. However not all mappings are valid to be arbitrarily accessed.

For example the vvar data used for virtual clocks on x86 [vvar_vclock] can only be accessed if 1) the kernel configuration enables virtual clocks and 2) the hypervisor provided the data for it. Only the VDSO itself has the necessary information to know this. Since commit e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping") the virtual clock data was split out into its own mapping, leading to EFAULT from read() during the validation.

Check for the VM_IO flag as a proxy. It is present for the VVAR mappings and MMIO ranges can be dangerous to access arbitrarily.

Reported-by: kernel test robot oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202412271148.2656e485-lkp@intel.com Fixes: e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping") Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()") Suggested-by: David Hildenbrand david@redhat.com Link: https://lore.kernel.org/lkml/e97c2a5d-c815-4936-a767-ac42a3220a90@redhat.com... Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de

Revert "selftests/mm: virtual_address_range: Avoid reading VVAR mappings"

This reverts commit 05cc5d292ac4238684b59922aecf59c932edefa0. --- tools/testing/selftests/mm/virtual_address_range.c | 4 ++++ tools/testing/selftests/mm/vm_util.c | 21 +++++++++++++++++++++ tools/testing/selftests/mm/vm_util.h | 1 + 3 files changed, 26 insertions(+)

diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c index 386e4e46fa65b98af78dee4bb30144eb2b51f528..b380e102b22f0a44654ab046f257e8c35e8d90e9 100644 --- a/tools/testing/selftests/mm/virtual_address_range.c +++ b/tools/testing/selftests/mm/virtual_address_range.c @@ -15,6 +15,7 @@ #include <sys/time.h> #include <fcntl.h>

+#include "vm_util.h" #include "../kselftest.h"

/* @@ -159,6 +160,9 @@ static int validate_complete_va_space(void) if (prot[0] != 'r') continue;

+ if (check_vmflag_io((void *)start_addr)) + continue; + /* * Confirm whether MAP_CHUNK_SIZE chunk can be found or not. * If write succeeds, no need to check MAP_CHUNK_SIZE - 1 diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c index 8468a19d6acca10c7e9228c03a935cdeb2402b5d..161fe03b07af78244efc669a36155ad603fa6f7d 100644 --- a/tools/testing/selftests/mm/vm_util.c +++ b/tools/testing/selftests/mm/vm_util.c @@ -400,3 +400,24 @@ unsigned long get_free_hugepages(void) fclose(f); return fhp; } + +bool check_vmflag_io(void *addr) +{ + char *saveptr, *flag, *strtok_arg; + char buffer[MAX_LINE_LENGTH]; + + strtok_arg = __get_smap_entry(addr, "VmFlags:", buffer, sizeof(buffer)); + if (!strtok_arg) + ksft_exit_fail_msg("%s: No VmFlags for %p\n", __func__, addr); + + while (true) { + flag = strtok_r(strtok_arg, " ", &saveptr); + if (!flag) + break; + if (strcmp(flag, "io") == 0) + return true; + strtok_arg = NULL; + } + + return false; +} diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h index 2eaed82099255e09ffd38ad9714994397f304685..b60ac68a9dc8893895f49946b258260f7a82218a 100644 --- a/tools/testing/selftests/mm/vm_util.h +++ b/tools/testing/selftests/mm/vm_util.h @@ -53,6 +53,7 @@ int uffd_unregister(int uffd, void *addr, uint64_t len); int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len, bool miss, bool wp, bool minor, uint64_t *ioctls); unsigned long get_free_hugepages(void); +bool check_vmflag_io(void *addr);

/* * On ppc64 this will only work with radix 2M hugepage size