diff options
Diffstat (limited to 'tools/testing/selftests/mm/prctl_thp_disable.c')
| -rw-r--r-- | tools/testing/selftests/mm/prctl_thp_disable.c | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/prctl_thp_disable.c b/tools/testing/selftests/mm/prctl_thp_disable.c new file mode 100644 index 000000000000..84b4a4b345af --- /dev/null +++ b/tools/testing/selftests/mm/prctl_thp_disable.c @@ -0,0 +1,291 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Basic tests for PR_GET/SET_THP_DISABLE prctl calls + * + * Author(s): Usama Arif <usamaarif642@gmail.com> + */ +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <sys/mman.h> +#include <linux/mman.h> +#include <sys/prctl.h> +#include <sys/wait.h> + +#include "../kselftest_harness.h" +#include "thp_settings.h" +#include "vm_util.h" + +#ifndef PR_THP_DISABLE_EXCEPT_ADVISED +#define PR_THP_DISABLE_EXCEPT_ADVISED (1 << 1) +#endif + +enum thp_collapse_type { + THP_COLLAPSE_NONE, + THP_COLLAPSE_MADV_NOHUGEPAGE, + THP_COLLAPSE_MADV_HUGEPAGE, /* MADV_HUGEPAGE before access */ + THP_COLLAPSE_MADV_COLLAPSE, /* MADV_COLLAPSE after access */ +}; + +/* + * Function to mmap a buffer, fault it in, madvise it appropriately (before + * page fault for MADV_HUGE, and after for MADV_COLLAPSE), and check if the + * mmap region is huge. + * Returns: + * 0 if test doesn't give hugepage + * 1 if test gives a hugepage + * -errno if mmap fails + */ +static int test_mmap_thp(enum thp_collapse_type madvise_buf, size_t pmdsize) +{ + char *mem, *mmap_mem; + size_t mmap_size; + int ret; + + /* For alignment purposes, we need twice the THP size. */ + mmap_size = 2 * pmdsize; + mmap_mem = (char *)mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (mmap_mem == MAP_FAILED) + return -errno; + + /* We need a THP-aligned memory area. */ + mem = (char *)(((uintptr_t)mmap_mem + pmdsize) & ~(pmdsize - 1)); + + if (madvise_buf == THP_COLLAPSE_MADV_HUGEPAGE) + madvise(mem, pmdsize, MADV_HUGEPAGE); + else if (madvise_buf == THP_COLLAPSE_MADV_NOHUGEPAGE) + madvise(mem, pmdsize, MADV_NOHUGEPAGE); + + /* Ensure memory is allocated */ + memset(mem, 1, pmdsize); + + if (madvise_buf == THP_COLLAPSE_MADV_COLLAPSE) + madvise(mem, pmdsize, MADV_COLLAPSE); + + /* HACK: make sure we have a separate VMA that we can check reliably. */ + mprotect(mem, pmdsize, PROT_READ); + + ret = check_huge_anon(mem, 1, pmdsize); + munmap(mmap_mem, mmap_size); + return ret; +} + +static void prctl_thp_disable_completely_test(struct __test_metadata *const _metadata, + size_t pmdsize, + enum thp_enabled thp_policy) +{ + ASSERT_EQ(prctl(PR_GET_THP_DISABLE, NULL, NULL, NULL, NULL), 1); + + /* tests after prctl overrides global policy */ + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize), 0); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_NOHUGEPAGE, pmdsize), 0); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize), 0); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 0); + + /* Reset to global policy */ + ASSERT_EQ(prctl(PR_SET_THP_DISABLE, 0, NULL, NULL, NULL), 0); + + /* tests after prctl is cleared, and only global policy is effective */ + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize), + thp_policy == THP_ALWAYS ? 1 : 0); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_NOHUGEPAGE, pmdsize), 0); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize), + thp_policy == THP_NEVER ? 0 : 1); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 1); +} + +FIXTURE(prctl_thp_disable_completely) +{ + struct thp_settings settings; + size_t pmdsize; +}; + +FIXTURE_VARIANT(prctl_thp_disable_completely) +{ + enum thp_enabled thp_policy; +}; + +FIXTURE_VARIANT_ADD(prctl_thp_disable_completely, never) +{ + .thp_policy = THP_NEVER, +}; + +FIXTURE_VARIANT_ADD(prctl_thp_disable_completely, madvise) +{ + .thp_policy = THP_MADVISE, +}; + +FIXTURE_VARIANT_ADD(prctl_thp_disable_completely, always) +{ + .thp_policy = THP_ALWAYS, +}; + +FIXTURE_SETUP(prctl_thp_disable_completely) +{ + if (!thp_available()) + SKIP(return, "Transparent Hugepages not available\n"); + + self->pmdsize = read_pmd_pagesize(); + if (!self->pmdsize) + SKIP(return, "Unable to read PMD size\n"); + + if (prctl(PR_SET_THP_DISABLE, 1, NULL, NULL, NULL)) + SKIP(return, "Unable to disable THPs completely for the process\n"); + + thp_save_settings(); + thp_read_settings(&self->settings); + self->settings.thp_enabled = variant->thp_policy; + self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT; + thp_write_settings(&self->settings); +} + +FIXTURE_TEARDOWN(prctl_thp_disable_completely) +{ + thp_restore_settings(); +} + +TEST_F(prctl_thp_disable_completely, nofork) +{ + prctl_thp_disable_completely_test(_metadata, self->pmdsize, variant->thp_policy); +} + +TEST_F(prctl_thp_disable_completely, fork) +{ + int ret = 0; + pid_t pid; + + /* Make sure prctl changes are carried across fork */ + pid = fork(); + ASSERT_GE(pid, 0); + + if (!pid) { + prctl_thp_disable_completely_test(_metadata, self->pmdsize, variant->thp_policy); + return; + } + + wait(&ret); + if (WIFEXITED(ret)) + ret = WEXITSTATUS(ret); + else + ret = -EINVAL; + ASSERT_EQ(ret, 0); +} + +static void prctl_thp_disable_except_madvise_test(struct __test_metadata *const _metadata, + size_t pmdsize, + enum thp_enabled thp_policy) +{ + ASSERT_EQ(prctl(PR_GET_THP_DISABLE, NULL, NULL, NULL, NULL), 3); + + /* tests after prctl overrides global policy */ + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize), 0); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_NOHUGEPAGE, pmdsize), 0); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize), + thp_policy == THP_NEVER ? 0 : 1); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 1); + + /* Reset to global policy */ + ASSERT_EQ(prctl(PR_SET_THP_DISABLE, 0, NULL, NULL, NULL), 0); + + /* tests after prctl is cleared, and only global policy is effective */ + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize), + thp_policy == THP_ALWAYS ? 1 : 0); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_NOHUGEPAGE, pmdsize), 0); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize), + thp_policy == THP_NEVER ? 0 : 1); + + ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 1); +} + +FIXTURE(prctl_thp_disable_except_madvise) +{ + struct thp_settings settings; + size_t pmdsize; +}; + +FIXTURE_VARIANT(prctl_thp_disable_except_madvise) +{ + enum thp_enabled thp_policy; +}; + +FIXTURE_VARIANT_ADD(prctl_thp_disable_except_madvise, never) +{ + .thp_policy = THP_NEVER, +}; + +FIXTURE_VARIANT_ADD(prctl_thp_disable_except_madvise, madvise) +{ + .thp_policy = THP_MADVISE, +}; + +FIXTURE_VARIANT_ADD(prctl_thp_disable_except_madvise, always) +{ + .thp_policy = THP_ALWAYS, +}; + +FIXTURE_SETUP(prctl_thp_disable_except_madvise) +{ + if (!thp_available()) + SKIP(return, "Transparent Hugepages not available\n"); + + self->pmdsize = read_pmd_pagesize(); + if (!self->pmdsize) + SKIP(return, "Unable to read PMD size\n"); + + if (prctl(PR_SET_THP_DISABLE, 1, PR_THP_DISABLE_EXCEPT_ADVISED, NULL, NULL)) + SKIP(return, "Unable to set PR_THP_DISABLE_EXCEPT_ADVISED\n"); + + thp_save_settings(); + thp_read_settings(&self->settings); + self->settings.thp_enabled = variant->thp_policy; + self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT; + thp_write_settings(&self->settings); +} + +FIXTURE_TEARDOWN(prctl_thp_disable_except_madvise) +{ + thp_restore_settings(); +} + +TEST_F(prctl_thp_disable_except_madvise, nofork) +{ + prctl_thp_disable_except_madvise_test(_metadata, self->pmdsize, variant->thp_policy); +} + +TEST_F(prctl_thp_disable_except_madvise, fork) +{ + int ret = 0; + pid_t pid; + + /* Make sure prctl changes are carried across fork */ + pid = fork(); + ASSERT_GE(pid, 0); + + if (!pid) { + prctl_thp_disable_except_madvise_test(_metadata, self->pmdsize, + variant->thp_policy); + return; + } + + wait(&ret); + if (WIFEXITED(ret)) + ret = WEXITSTATUS(ret); + else + ret = -EINVAL; + ASSERT_EQ(ret, 0); +} + +TEST_HARNESS_MAIN |