Re: Bug in Kernel 6.8.x, 6.9.x Causing Trace/Panic During Shutdown/Reboot

[Steven Rostedt <rostedt@xxxxxxxxxxx>]

On Thu, 30 May 2024 16:02:37 +0300
Ilkka Naulapää <digirigawa@xxxxxxxxx> wrote:

> applied your patch and here's the output.
> 

Unfortunately, it doesn't give me any new information. I added one more
BUG on, want to try this? Otherwise, I'm pretty much at a lost. :-/

-- Steve

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index de5b72216b1a..a090495e78c9 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -39,13 +39,17 @@ static struct inode *tracefs_alloc_inode(struct super_block *sb)
 		return NULL;
 
 	ti->flags = 0;
+	ti->magic = 20240823;
 
 	return &ti->vfs_inode;
 }
 
 static void tracefs_free_inode(struct inode *inode)
 {
-	kmem_cache_free(tracefs_inode_cachep, get_tracefs(inode));
+	struct tracefs_inode *ti = get_tracefs(inode);
+
+	BUG_ON(ti->magic != 20240823);
+	kmem_cache_free(tracefs_inode_cachep, ti);
 }
 
 static ssize_t default_read_file(struct file *file, char __user *buf,
@@ -147,16 +151,6 @@ static const struct inode_operations tracefs_dir_inode_operations = {
 	.rmdir		= tracefs_syscall_rmdir,
 };
 
-struct inode *tracefs_get_inode(struct super_block *sb)
-{
-	struct inode *inode = new_inode(sb);
-	if (inode) {
-		inode->i_ino = get_next_ino();
-		inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode);
-	}
-	return inode;
-}
-
 struct tracefs_mount_opts {
 	kuid_t uid;
 	kgid_t gid;
@@ -384,6 +378,7 @@ static void tracefs_dentry_iput(struct dentry *dentry, struct inode *inode)
 		return;
 
 	ti = get_tracefs(inode);
+	BUG_ON(ti->magic != 20240823);
 	if (ti && ti->flags & TRACEFS_EVENT_INODE)
 		eventfs_set_ef_status_free(dentry);
 	iput(inode);
@@ -568,6 +563,18 @@ struct dentry *eventfs_end_creating(struct dentry *dentry)
 	return dentry;
 }
 
+struct inode *tracefs_get_inode(struct super_block *sb)
+{
+	struct inode *inode = new_inode(sb);
+
+	BUG_ON(sb->s_op != &tracefs_super_operations);
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode);
+	}
+	return inode;
+}
+
 /**
  * tracefs_create_file - create a file in the tracefs filesystem
  * @name: a pointer to a string containing the name of the file to create.
diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h
index 69c2b1d87c46..9059b8b11bb6 100644
--- a/fs/tracefs/internal.h
+++ b/fs/tracefs/internal.h
@@ -9,12 +9,15 @@ enum {
 struct tracefs_inode {
 	unsigned long           flags;
 	void                    *private;
+	unsigned long		magic;
 	struct inode            vfs_inode;
 };
 
 static inline struct tracefs_inode *get_tracefs(const struct inode *inode)
 {
-	return container_of(inode, struct tracefs_inode, vfs_inode);
+	struct tracefs_inode *ti = container_of(inode, struct tracefs_inode, vfs_inode);
+	BUG_ON(ti->magic != 20240823);
+	return ti;
 }
 
 struct dentry *tracefs_start_creating(const char *name, struct dentry *parent);