From 4ba281d5bd9907355e6b79fb72049c9ed50cc670 Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 11 May 2018 16:01:39 -0700 Subject: [PATCH] lib/find_bit_benchmark.c: avoid soft lockup in test_find_first_bit() test_find_first_bit() is intentionally sub-optimal, and may cause soft lockup due to long time of run on some systems. So decrease length of bitmap to traverse to avoid lockup. With the change below, time of test execution doesn't exceed 0.2 seconds on my testing system. Link: http://lkml.kernel.org/r/20180420171949.15710-1-ynorov@caviumnetworks.com Fixes: 4441fca0a27f5 ("lib: test module for find_*_bit() functions") Signed-off-by: Yury Norov Reviewed-by: Andrew Morton Reported-by: Fengguang Wu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/find_bit_benchmark.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c index 5985a25e6cbc..5367ffa5c18f 100644 --- a/lib/find_bit_benchmark.c +++ b/lib/find_bit_benchmark.c @@ -132,7 +132,12 @@ static int __init find_bit_test(void) test_find_next_bit(bitmap, BITMAP_LEN); test_find_next_zero_bit(bitmap, BITMAP_LEN); test_find_last_bit(bitmap, BITMAP_LEN); - test_find_first_bit(bitmap, BITMAP_LEN); + + /* + * test_find_first_bit() may take some time, so + * traverse only part of bitmap to avoid soft lockup. + */ + test_find_first_bit(bitmap, BITMAP_LEN / 10); test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN); pr_err("\nStart testing find_bit() with sparse bitmap\n");