diff options
authorYury Norov <>2018-05-12 02:01:39 +0300
committerLinus Torvalds <>2018-05-12 03:28:45 +0300
commit4ba281d5bd9907355e6b79fb72049c9ed50cc670 (patch)
parentc9cf87ea6a4725bc586cc5776c3fb6042a264b7d (diff)
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: 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 <>
1 files changed, 6 insertions, 1 deletions
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");