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

[Steven Rostedt]

On Wed, 29 May 2024 14:47:57 -0400
Steven Rostedt <rost...@goodmis.org> wrote:

> Let me make a debug patch (that crashes on this issue) for that kernel,
> and perhaps you could bisect it?

Can you try this on 6.6-rc1 and see if it gives you any other splats?

Hmm, you can switch it to WARN_ON and that way it may not crash the
machine, and you can use dmesg to get the output.

Thanks,

-- 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..9f6f303a9e58 100644
--- a/fs/tracefs/internal.h
+++ b/fs/tracefs/internal.h
@@ -9,6 +9,7 @@ enum {
 struct tracefs_inode {
        unsigned long           flags;
        void                    *private;
+       unsigned long           magic;
        struct inode            vfs_inode;
 };