selftests/mm: reuse read_pmd_pagesize() in COW selftest

Patch series "mm: (pte|pmd)_mkdirty() should not unconditionally allow for
write access".

This is the follow-up on [1], adding selftests (testing for known issues
we added workarounds for and other issues that haven't been fixed yet),
fixing sparc64, reverting the workarounds, and perform one cleanup.

The patch from [1] was modified slightly (updated/extended patch
description, dropped one unnecessary NOP instruction from the ASM in
__pte_mkhwwrite()).

Retested on x86_64 and sparc64 (sun4u in QEMU).

I scanned most architectures to make sure their (pte|pmd)_mkdirty()
handling is correct.  To be sure, we can run the selftests and find out if
other architectures are still affectes (loongarch was fixed recently as
well).

Based on master for now. I don't expect surprises regarding mm-tress, but
I can rebase if there are any problems.

This patch (of 6):

The COW selftest can deal with THP not being configured.  So move error
handling of read_pmd_pagesize() into the callers such that we can reuse it
in the COW selftest.

Link: https://lkml.kernel.org/r/20230411142512.438404-1-david@redhat.com
Link: https://lkml.kernel.org/r/20221212130213.136267-1-david@redhat.com
Link: https://lkml.kernel.org/r/20230411142512.438404-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index 0eb2e8180aa5bba6c855e93da2ffc8f8cca8545d..dc9d6fe860285198937c88f554bbab8bdf8caac5 100644 (file)
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -45,34 +45,6 @@ static size_t hugetlbsizes[10];
 static int gup_fd;
 static bool has_huge_zeropage;
 
-static void detect_thpsize(void)
-{
-       int fd = open("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size",
-                     O_RDONLY);
-       size_t size = 0;
-       char buf[15];
-       int ret;
-
-       if (fd < 0)
-               return;
-
-       ret = pread(fd, buf, sizeof(buf), 0);
-       if (ret > 0 && ret < sizeof(buf)) {
-               buf[ret] = 0;
-
-               size = strtoul(buf, NULL, 10);
-               if (size < pagesize)
-                       size = 0;
-               if (size > 0) {
-                       thpsize = size;
-                       ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
-                                      thpsize / 1024);
-               }
-       }
-
-       close(fd);
-}
-
 static void detect_huge_zeropage(void)
 {
        int fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page",
@@ -1741,7 +1713,10 @@ int main(int argc, char **argv)
        int err;
 
        pagesize = getpagesize();
-       detect_thpsize();
+       thpsize = read_pmd_pagesize();
+       if (thpsize)
+               ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
+                              thpsize / 1024);
        detect_hugetlbsizes();
        detect_huge_zeropage();
 

diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index 64126c8cd561298627b9ed748074068abc0812c5..97adc0f34f9c048680e5fd83d823e4d318637f9f 100644 (file)
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -1476,6 +1476,10 @@ int main(int argc, const char **argv)
 
        page_size = getpagesize();
        hpage_pmd_size = read_pmd_pagesize();
+       if (!hpage_pmd_size) {
+               printf("Reading PMD pagesize failed");
+               exit(EXIT_FAILURE);
+       }
        hpage_pmd_nr = hpage_pmd_size / page_size;
 
        default_settings.khugepaged.max_ptes_none = hpage_pmd_nr - 1;

diff --git a/tools/testing/selftests/mm/soft-dirty.c b/tools/testing/selftests/mm/soft-dirty.c
index 21d8830c5f243aaf32a0b5eeae181775225056de..cc5f144430d4d246fa5dfd09445b6ecc78f46a81 100644 (file)
--- a/tools/testing/selftests/mm/soft-dirty.c
+++ b/tools/testing/selftests/mm/soft-dirty.c
@@ -80,6 +80,9 @@ static void test_hugepage(int pagemap_fd, int pagesize)
        int i, ret;
        size_t hpage_len = read_pmd_pagesize();
 
+       if (!hpage_len)
+               ksft_exit_fail_msg("Reading PMD pagesize failed");
+
        map = memalign(hpage_len, hpage_len);
        if (!map)
                ksft_exit_fail_msg("memalign failed\n");

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index b8558c7f1a3936da5e44887a3d7badd11ef4cdb6..0e74635c8c3d97fca497e73ac1e41a17f1677a0e 100644 (file)
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -300,6 +300,10 @@ int main(int argc, char **argv)
        pagesize = getpagesize();
        pageshift = ffs(pagesize) - 1;
        pmd_pagesize = read_pmd_pagesize();
+       if (!pmd_pagesize) {
+               printf("Reading PMD pagesize failed\n");
+               exit(EXIT_FAILURE);
+       }
 
        split_pmd_thp();
        split_pte_mapped_thp();

diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 40e795624ff33acdea21f068fbb52b5386d79fa2..8dc74dd022c2a43efe4bc236894f046f09ee262e 100644 (file)
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -84,12 +84,12 @@ uint64_t read_pmd_pagesize(void)
 
        fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
        if (fd == -1)
-               ksft_exit_fail_msg("Open hpage_pmd_size failed\n");
+               return 0;
 
        num_read = read(fd, buf, 19);
        if (num_read < 1) {
                close(fd);
-               ksft_exit_fail_msg("Read hpage_pmd_size failed\n");
+               return 0;
        }
        buf[num_read] = '\0';
        close(fd);