[PATCH 2/4] KVM: Only log about debugfs directory collision once

[Oliver Upton]

In all likelihood, a debugfs directory name collision is the result of a
userspace bug. If userspace closes the VM fd without releasing all
references to said VM then the debugfs directory is never cleaned.

Even a ratelimited print statement can fill up dmesg, making it
particularly annoying for the person debugging what exactly went wrong.
Furthermore, a userspace that wants to be a nuisance could clog up the
logs by deliberately holding a VM reference after closing the VM fd.

Dial back logging to print at most once, given that userspace is most
likely to blame. Leave the statement in place for the small chance that
KVM actually got it wrong.

Cc: stable at kernel.org
Fixes: 85cd39af14f4 ("KVM: Do not leak memory for duplicate debugfs directories")
Signed-off-by: Oliver Upton <oupton at google.com>
---
 virt/kvm/kvm_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 69c318fdff61..38b30bd60f34 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -959,7 +959,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
 	mutex_lock(&kvm_debugfs_lock);
 	dent = debugfs_lookup(dir_name, kvm_debugfs_dir);
 	if (dent) {
-		pr_warn_ratelimited("KVM: debugfs: duplicate directory %s\n", dir_name);
+		pr_warn_once("KVM: debugfs: duplicate directory %s\n", dir_name);
 		dput(dent);
 		mutex_unlock(&kvm_debugfs_lock);
 		return 0;
-- 
2.35.1.1094.g7c7d902a7c-goog