mm/kfence: print disabling or re-enabling message

By printing information, we can friendly prompt the status change
information of kfence by dmesg and record by syslog.

Also, set kfence_enabled to false only when needed.

Link: https://lkml.kernel.org/r/20220518073105.3160335-1-liu.yun@linux.dev
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Co-developed-by: Marco Elver <elver@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 6e69986c3f0de66084e6b4d35e410c762dec011a..2b9f89749154c34515f72734275dfd2d9e9b0a35 100644 (file)
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -69,8 +69,11 @@ static int param_set_sample_interval(const char *val, const struct kernel_param
        if (ret < 0)
                return ret;
 
-       if (!num) /* Using 0 to indicate KFENCE is disabled. */
+       /* Using 0 to indicate KFENCE is disabled. */
+       if (!num && READ_ONCE(kfence_enabled)) {
+               pr_info("disabled\n");
                WRITE_ONCE(kfence_enabled, false);
+       }
 
        *((unsigned long *)kp->arg) = num;
 
@@ -898,6 +901,7 @@ static int kfence_enable_late(void)
 
        WRITE_ONCE(kfence_enabled, true);
        queue_delayed_work(system_unbound_wq, &kfence_timer, 0);
+       pr_info("re-enabled\n");
        return 0;
 }