From 9330694de59f17e110a58be486a2c64d32bab42f Mon Sep 17 00:00:00 2001 From: Zach O'Keefe Date: Wed, 6 Jul 2022 16:59:34 -0700 Subject: [PATCH] selftests/vm: add MADV_COLLAPSE collapse context to selftests Add madvise collapse context to hugepage collapse selftests. This context is tested with /sys/kernel/mm/transparent_hugepage/enabled set to "never" in order to avoid unwanted interaction with khugepaged during testing. Also, refactor updates to sysfs THP settings using a stack so that the THP settings from nested callers can be restored. Link: https://lkml.kernel.org/r/20220706235936.2197195-17-zokeefe@google.com Signed-off-by: Zach O'Keefe Cc: Alex Shi Cc: Andrea Arcangeli Cc: Arnd Bergmann Cc: Axel Rasmussen Cc: Chris Kennelly Cc: Chris Zankel Cc: David Hildenbrand Cc: David Rientjes Cc: Helge Deller Cc: Hugh Dickins Cc: Ivan Kokshaysky Cc: James Bottomley Cc: Jens Axboe Cc: "Kirill A. Shutemov" Cc: Matthew Wilcox Cc: Matt Turner Cc: Max Filippov Cc: Miaohe Lin Cc: Michal Hocko Cc: Minchan Kim Cc: Pasha Tatashin Cc: Pavel Begunkov Cc: Peter Xu Cc: Rongwei Wang Cc: SeongJae Park Cc: Song Liu Cc: Thomas Bogendoerfer Cc: Vlastimil Babka Cc: Yang Shi Cc: Zi Yan Cc: Dan Carpenter Cc: "Souptick Joarder (HPE)" Signed-off-by: Andrew Morton --- tools/testing/selftests/vm/khugepaged.c | 169 +++++++++++++++++------- 1 file changed, 124 insertions(+), 45 deletions(-) diff --git a/tools/testing/selftests/vm/khugepaged.c b/tools/testing/selftests/vm/khugepaged.c index eb6f5bbacff1..780f04440e15 100644 --- a/tools/testing/selftests/vm/khugepaged.c +++ b/tools/testing/selftests/vm/khugepaged.c @@ -14,6 +14,9 @@ #ifndef MADV_PAGEOUT #define MADV_PAGEOUT 21 #endif +#ifndef MADV_COLLAPSE +#define MADV_COLLAPSE 25 +#endif #define BASE_ADDR ((void *)(1UL << 30)) static unsigned long hpage_pmd_size; @@ -95,18 +98,6 @@ struct settings { struct khugepaged_settings khugepaged; }; -static struct settings default_settings = { - .thp_enabled = THP_MADVISE, - .thp_defrag = THP_DEFRAG_ALWAYS, - .shmem_enabled = SHMEM_NEVER, - .use_zero_page = 0, - .khugepaged = { - .defrag = 1, - .alloc_sleep_millisecs = 10, - .scan_sleep_millisecs = 10, - }, -}; - static struct settings saved_settings; static bool skip_settings_restore; @@ -284,6 +275,39 @@ static void write_settings(struct settings *settings) write_num("khugepaged/pages_to_scan", khugepaged->pages_to_scan); } +#define MAX_SETTINGS_DEPTH 4 +static struct settings settings_stack[MAX_SETTINGS_DEPTH]; +static int settings_index; + +static struct settings *current_settings(void) +{ + if (!settings_index) { + printf("Fail: No settings set"); + exit(EXIT_FAILURE); + } + return settings_stack + settings_index - 1; +} + +static void push_settings(struct settings *settings) +{ + if (settings_index >= MAX_SETTINGS_DEPTH) { + printf("Fail: Settings stack exceeded"); + exit(EXIT_FAILURE); + } + settings_stack[settings_index++] = *settings; + write_settings(current_settings()); +} + +static void pop_settings(void) +{ + if (settings_index <= 0) { + printf("Fail: Settings stack empty"); + exit(EXIT_FAILURE); + } + --settings_index; + write_settings(current_settings()); +} + static void restore_settings(int sig) { if (skip_settings_restore) @@ -327,14 +351,6 @@ static void save_settings(void) signal(SIGQUIT, restore_settings); } -static void adjust_settings(void) -{ - - printf("Adjust settings..."); - write_settings(&default_settings); - success("OK"); -} - #define MAX_LINE_LENGTH 500 static bool check_for_pattern(FILE *fp, char *pattern, char *buf) @@ -493,6 +509,38 @@ static void validate_memory(int *p, unsigned long start, unsigned long end) } } +static void madvise_collapse(const char *msg, char *p, bool expect) +{ + int ret; + struct settings settings = *current_settings(); + + printf("%s...", msg); + /* Sanity check */ + if (check_huge(p)) { + printf("Unexpected huge page\n"); + exit(EXIT_FAILURE); + } + + /* + * Prevent khugepaged interference and tests that MADV_COLLAPSE + * ignores /sys/kernel/mm/transparent_hugepage/enabled + */ + settings.thp_enabled = THP_NEVER; + push_settings(&settings); + + /* Clear VM_NOHUGEPAGE */ + madvise(p, hpage_pmd_size, MADV_HUGEPAGE); + ret = madvise(p, hpage_pmd_size, MADV_COLLAPSE); + if (((bool)ret) == expect) + fail("Fail: Bad return value"); + else if (check_huge(p) != expect) + fail("Fail: check_huge()"); + else + success("OK"); + + pop_settings(); +} + #define TICK 500000 static bool wait_for_scan(const char *msg, char *p) { @@ -542,11 +590,11 @@ static void khugepaged_collapse(const char *msg, char *p, bool expect) static void alloc_at_fault(void) { - struct settings settings = default_settings; + struct settings settings = *current_settings(); char *p; settings.thp_enabled = THP_ALWAYS; - write_settings(&settings); + push_settings(&settings); p = alloc_mapping(); *p = 1; @@ -556,7 +604,7 @@ static void alloc_at_fault(void) else fail("Fail"); - write_settings(&default_settings); + pop_settings(); madvise(p, page_size, MADV_DONTNEED); printf("Split huge PMD on MADV_DONTNEED..."); @@ -602,11 +650,11 @@ static void collapse_single_pte_entry(struct collapse_context *c) static void collapse_max_ptes_none(struct collapse_context *c) { int max_ptes_none = hpage_pmd_nr / 2; - struct settings settings = default_settings; + struct settings settings = *current_settings(); void *p; settings.khugepaged.max_ptes_none = max_ptes_none; - write_settings(&settings); + push_settings(&settings); p = alloc_mapping(); @@ -623,7 +671,7 @@ static void collapse_max_ptes_none(struct collapse_context *c) } munmap(p, hpage_pmd_size); - write_settings(&default_settings); + pop_settings(); } static void collapse_swapin_single_pte(struct collapse_context *c) @@ -703,7 +751,6 @@ static void collapse_single_pte_entry_compound(struct collapse_context *c) p = alloc_hpage(); madvise(p, hpage_pmd_size, MADV_NOHUGEPAGE); - printf("Split huge page leaving single PTE mapping compound page..."); madvise(p + page_size, hpage_pmd_size - page_size, MADV_DONTNEED); if (!check_huge(p)) @@ -864,7 +911,7 @@ static void collapse_fork_compound(struct collapse_context *c) c->collapse("Collapse PTE table full of compound pages in child", p, true); write_num("khugepaged/max_ptes_shared", - default_settings.khugepaged.max_ptes_shared); + current_settings()->khugepaged.max_ptes_shared); validate_memory(p, 0, hpage_pmd_size); munmap(p, hpage_pmd_size); @@ -943,9 +990,21 @@ static void collapse_max_ptes_shared(struct collapse_context *c) munmap(p, hpage_pmd_size); } -int main(void) +int main(int argc, const char **argv) { struct collapse_context c; + struct settings default_settings = { + .thp_enabled = THP_MADVISE, + .thp_defrag = THP_DEFRAG_ALWAYS, + .shmem_enabled = SHMEM_NEVER, + .use_zero_page = 0, + .khugepaged = { + .defrag = 1, + .alloc_sleep_millisecs = 10, + .scan_sleep_millisecs = 10, + }, + }; + const char *tests = argc == 1 ? "all" : argv[1]; setbuf(stdout, NULL); @@ -959,26 +1018,46 @@ int main(void) default_settings.khugepaged.pages_to_scan = hpage_pmd_nr * 8; save_settings(); - adjust_settings(); + push_settings(&default_settings); alloc_at_fault(); - printf("\n*** Testing context: khugepaged ***\n"); - c.collapse = &khugepaged_collapse; - c.enforce_pte_scan_limits = true; + if (!strcmp(tests, "khugepaged") || !strcmp(tests, "all")) { + printf("\n*** Testing context: khugepaged ***\n"); + c.collapse = &khugepaged_collapse; + c.enforce_pte_scan_limits = true; - collapse_full(&c); - collapse_empty(&c); - collapse_single_pte_entry(&c); - collapse_max_ptes_none(&c); - collapse_swapin_single_pte(&c); - collapse_max_ptes_swap(&c); - collapse_single_pte_entry_compound(&c); - collapse_full_of_compound(&c); - collapse_compound_extreme(&c); - collapse_fork(&c); - collapse_fork_compound(&c); - collapse_max_ptes_shared(&c); + collapse_full(&c); + collapse_empty(&c); + collapse_single_pte_entry(&c); + collapse_max_ptes_none(&c); + collapse_swapin_single_pte(&c); + collapse_max_ptes_swap(&c); + collapse_single_pte_entry_compound(&c); + collapse_full_of_compound(&c); + collapse_compound_extreme(&c); + collapse_fork(&c); + collapse_fork_compound(&c); + collapse_max_ptes_shared(&c); + } + if (!strcmp(tests, "madvise") || !strcmp(tests, "all")) { + printf("\n*** Testing context: madvise ***\n"); + c.collapse = &madvise_collapse; + c.enforce_pte_scan_limits = false; + + collapse_full(&c); + collapse_empty(&c); + collapse_single_pte_entry(&c); + collapse_max_ptes_none(&c); + collapse_swapin_single_pte(&c); + collapse_max_ptes_swap(&c); + collapse_single_pte_entry_compound(&c); + collapse_full_of_compound(&c); + collapse_compound_extreme(&c); + collapse_fork(&c); + collapse_fork_compound(&c); + collapse_max_ptes_shared(&c); + } restore_settings(0); }