From: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxxxxxxxx Fixes: 4441fca0a27f5 ("lib: test module for find_*_bit() functions") Signed-off-by: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/find_bit_benchmark.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff -puN lib/find_bit_benchmark.c~lib-avoid-soft-lockup-in-test_find_first_bit lib/find_bit_benchmark.c --- a/lib/find_bit_benchmark.c~lib-avoid-soft-lockup-in-test_find_first_bit +++ a/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"); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
