There're some random failure for split_huge_page_test when khugepaged collapses pages into pmd again which had split by the test.
Prevent the khugepaged's collapses for split page by setting the mapped pmd-huge-page with MADV_NOHUGEPAGE before split. Suggested-by: Kevin Brodsky <[email protected]> Suggested-by: Lorenzo Stoakes (ARM) <[email protected]> Signed-off-by: Yeoreum Yun <[email protected]> --- tools/testing/selftests/mm/split_huge_page_test.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index 86a603692826..4bbad892bc57 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -168,6 +168,14 @@ static char *allocate_zero_filled_hugepage(size_t len) return result; } +static void madv_nohuge(void *addr, size_t len) +{ + if (!madvise(addr, len, MADV_NOHUGEPAGE)) + return; + + ksft_exit_fail_msg("MADV_NOHUGEPAGE failed, err=%d\n", errno); +} + static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hpages, size_t len) { unsigned long rss_anon_before, rss_anon_after; @@ -180,6 +188,9 @@ static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hp if (!rss_anon_before) ksft_exit_fail_msg("No RssAnon is allocated before split\n"); + /* Prevent khugepaged from collapsing the pages. */ + madv_nohuge(one_page, len); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, 0); @@ -227,6 +238,9 @@ static void split_pmd_thp_to_order(int order) if (!check_huge_anon(one_page, 4 * pmd_pagesize, 4, pmd_pagesize)) ksft_exit_fail_msg("No THP is allocated\n"); + /* Prevent khugepaged from collapsing the pages. */ + madv_nohuge(one_page, len); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, order); @@ -275,6 +289,9 @@ static void split_pte_mapped_thp(void) goto out; } + /* Prevent khugepaged from collapsing the pages. */ + madv_nohuge(thp_area, thp_area_size); + /* * To challenge spitting code, we will mremap a single page of each * THP (page[i] of thp[i]) in the thp_area into page_area. This will @@ -542,6 +559,8 @@ static int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, ksft_test_result_skip("Pagecache folio split skipped\n"); return -2; } + /* Prevent khugepaged from collapsing the pages. */ + madv_nohuge(*addr, fd_size); return 0; err_out_close: close(*fd); -- 2.43.0
