On Mon, 24 Jan 2022 at 03:37, 'Peng Liu' via kasan-dev
<kasan-dev@googlegroups.com> wrote:

The parameter kfence_sample_interval can be set via boot parameter
and late shell command. However, KFENCE test case just use compile
time CONFIG_KFENCE_SAMPLE_INTERVAL, this will make KFENCE test case
not run as user desired. This patch will make KFENCE test case
compatible with run-time-set sample interval.

Signed-off-by: Peng Liu <liupeng256@huawei.com>
---
 include/linux/kfence.h  | 2 ++
 mm/kfence/core.c        | 3 ++-
 mm/kfence/kfence_test.c | 8 ++++----
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/include/linux/kfence.h b/include/linux/kfence.h
index bf91b76b87ee..0fc913a7f017 100644
--- a/include/linux/kfence.h
+++ b/include/linux/kfence.h
@@ -19,6 +19,8 @@

 extern bool kfence_enabled;
 extern unsigned long kfence_num_objects;
+extern unsigned long kfence_sample_interval;
+
 /*
  * We allocate an even number of pages, as it simplifies calculations to map
  * address to metadata indices; effectively, the very first page serves as an
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 2301923182b8..e2fcae34cc84 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -50,7 +50,8 @@

 bool kfence_enabled __read_mostly;

-static unsigned long kfence_sample_interval __read_mostly = CONFIG_KFENCE_SAMPLE_INTERVAL;
+unsigned long kfence_sample_interval __read_mostly = CONFIG_KFENCE_SAMPLE_INTERVAL;
+EXPORT_SYMBOL(kfence_sample_interval); /* Export for test modules. */

While it would make some situations more convenient, I've wanted to
avoid exporting a new symbol just for the test. And in most cases it
only makes sense to run the test on a custom debug kernel.

Why do you need this?

To automatically do more tests.

Should you really need this, I suggest at least using
EXPORT_SYMBOL_GPL. Should you want it, you can resend this patch
standalone detached from the rest.

Thanks,
-- Marco
.

When KFENCE pool size can be adjusted by boot parameters(assumption),
automatically test and train KFENCE may be useful. So far, exporting
kfence.sample_interval is not necessary. 

Thanks,
-- Peng Liu
.