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 <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/vm/khugepaged.c b/tools/testing/selftests/vm/khugepaged.c
index eb6f5bbacff1365f01da5645aac2ad6cdf9a241a..780f04440e154e54f46bcc8b00f7832689dc579d 100644 (file)
--- 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;
-
-       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, "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);
+       }
+       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);
 }