selftest/mm: ksm_functional_tests: test in mmap_and_merge_range() if anything got merged
Let's extend mmap_and_merge_range() to test if anything in the current process was merged. range_maps_duplicates() is too unreliable for that use case, so instead look at KSM stats. Trigger a complete unmerge first, to cleanup the stable tree and stabilize accounting of merged pages. Note that we're using /proc/self/ksm_merging_pages instead of /proc/self/ksm_stat, because that one is available in more existing kernels. If /proc/self/ksm_merging_pages can't be opened, we can't perform any checks and simply skip them. We have to special-case the shared zeropage for now. But the only user -- test_unmerge_zero_pages() -- performs its own merge checks. Link: https://lkml.kernel.org/r/20230803143208.383663-7-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Peter Xu <peterx@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: liubo <liubo254@huawei.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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@ -30,6 +30,7 @@
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static int ksm_fd;
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static int ksm_fd;
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static int ksm_full_scans_fd;
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static int ksm_full_scans_fd;
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static int proc_self_ksm_stat_fd;
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static int proc_self_ksm_stat_fd;
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static int proc_self_ksm_merging_pages_fd;
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static int ksm_use_zero_pages_fd;
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static int ksm_use_zero_pages_fd;
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static int pagemap_fd;
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static int pagemap_fd;
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static size_t pagesize;
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static size_t pagesize;
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@ -88,6 +89,22 @@ static long get_my_ksm_zero_pages(void)
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return my_ksm_zero_pages;
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return my_ksm_zero_pages;
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}
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}
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static long get_my_merging_pages(void)
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{
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char buf[10];
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ssize_t ret;
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if (proc_self_ksm_merging_pages_fd < 0)
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return proc_self_ksm_merging_pages_fd;
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ret = pread(proc_self_ksm_merging_pages_fd, buf, sizeof(buf) - 1, 0);
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if (ret <= 0)
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return -errno;
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buf[ret] = 0;
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return strtol(buf, NULL, 10);
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}
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static long ksm_get_full_scans(void)
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static long ksm_get_full_scans(void)
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{
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{
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char buf[10];
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char buf[10];
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@ -120,11 +137,29 @@ static int ksm_merge(void)
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return 0;
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return 0;
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}
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}
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static int ksm_unmerge(void)
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{
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if (write(ksm_fd, "2", 1) != 1)
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return -errno;
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return 0;
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}
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static char *mmap_and_merge_range(char val, unsigned long size, bool use_prctl)
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static char *mmap_and_merge_range(char val, unsigned long size, bool use_prctl)
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{
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{
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char *map;
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char *map;
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int ret;
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int ret;
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/* Stabilize accounting by disabling KSM completely. */
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if (ksm_unmerge()) {
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ksft_test_result_fail("Disabling (unmerging) KSM failed\n");
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goto unmap;
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}
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if (get_my_merging_pages() > 0) {
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ksft_test_result_fail("Still pages merged\n");
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goto unmap;
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}
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map = mmap(NULL, size, PROT_READ|PROT_WRITE,
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map = mmap(NULL, size, PROT_READ|PROT_WRITE,
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MAP_PRIVATE|MAP_ANON, -1, 0);
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MAP_PRIVATE|MAP_ANON, -1, 0);
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if (map == MAP_FAILED) {
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if (map == MAP_FAILED) {
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@ -160,6 +195,16 @@ static char *mmap_and_merge_range(char val, unsigned long size, bool use_prctl)
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ksft_test_result_fail("Running KSM failed\n");
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ksft_test_result_fail("Running KSM failed\n");
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goto unmap;
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goto unmap;
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}
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}
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/*
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* Check if anything was merged at all. Ignore the zero page that is
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* accounted differently (depending on kernel support).
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*/
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if (val && !get_my_merging_pages()) {
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ksft_test_result_fail("No pages got merged\n");
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goto unmap;
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}
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return map;
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return map;
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unmap:
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unmap:
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munmap(map, size);
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munmap(map, size);
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@ -473,6 +518,8 @@ int main(int argc, char **argv)
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if (pagemap_fd < 0)
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if (pagemap_fd < 0)
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ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n");
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ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n");
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proc_self_ksm_stat_fd = open("/proc/self/ksm_stat", O_RDONLY);
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proc_self_ksm_stat_fd = open("/proc/self/ksm_stat", O_RDONLY);
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proc_self_ksm_merging_pages_fd = open("/proc/self/ksm_merging_pages",
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O_RDONLY);
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ksm_use_zero_pages_fd = open("/sys/kernel/mm/ksm/use_zero_pages", O_RDWR);
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ksm_use_zero_pages_fd = open("/sys/kernel/mm/ksm/use_zero_pages", O_RDWR);
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test_unmerge();
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test_unmerge();
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