When 'echo 4 > /proc/sys/vm/drop_caches' the message is disabled,
but there is no interface to enable the message, only by restarting
the way, so add the 'echo 0 > /proc/sys/vm/drop_caches' way to
enabled the message again.
Signed-off-by: Ruiwu Chen <rwchen404@xxxxxxxxx>
---
v2: - updated Documentation/ to note this new API.
- renamed the variable.
- rebase this on top of sysctl-next [1].
[1] https://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl.git/log/?h=sysctl-next
Documentation/admin-guide/sysctl/vm.rst | 11 ++++++++++-
fs/drop_caches.c | 11 +++++++----
2 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst
index f48eaa98d22d..ef73d36e8b84 100644
--- a/Documentation/admin-guide/sysctl/vm.rst
+++ b/Documentation/admin-guide/sysctl/vm.rst
@@ -266,7 +266,16 @@ used::
cat (1234): drop_caches: 3
These are informational only. They do not mean that anything is wrong
-with your system. To disable them, echo 4 (bit 2) into drop_caches.
+with your system.
+
+To disable informational::
+
+ echo 4 > /proc/sys/vm/drop_caches
+
+To enable informational::
+
+ echo 0 > /proc/sys/vm/drop_caches
+
enable_soft_offline
===================
diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index 019a8b4eaaf9..a49af7023886 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -57,7 +57,7 @@ static int drop_caches_sysctl_handler(const struct ctl_table *table, int write,
if (ret)
return ret;
if (write) {
- static int stfu;
+ static bool silent;
if (sysctl_drop_caches & 1) {
lru_add_drain_all();
@@ -68,12 +68,15 @@ static int drop_caches_sysctl_handler(const struct ctl_table *table, int write,
drop_slab();
count_vm_event(DROP_SLAB);
}
- if (!stfu) {
+ if (!silent) {
pr_info("%s (%d): drop_caches: %d\n",
current->comm, task_pid_nr(current),
sysctl_drop_caches);
}
- stfu |= sysctl_drop_caches & 4;
+ if (sysctl_drop_caches == 0)
+ silent = true;
+ else if (sysctl_drop_caches == 4)
+ silent = false;
}
return 0;
}
@@ -85,7 +88,7 @@ static const struct ctl_table drop_caches_table[] = {
.maxlen = sizeof(int),
.mode = 0200,
.proc_handler = drop_caches_sysctl_handler,
- .extra1 = SYSCTL_ONE,
+ .extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_FOUR,
},
};
--
2.27.0
