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

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Date: Wed, 29 May 2024 15:48:24 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Ilkka Naulapää <digirigawa@...il.com>
Cc: "Linux regression tracking (Thorsten Leemhuis)"
 <regressions@...mhuis.info>, Linux regressions mailing list
 <regressions@...ts.linux.dev>, stable@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: Bug in Kernel 6.8.x, 6.9.x Causing Trace/Panic During
 Shutdown/Reboot

On Wed, 29 May 2024 14:47:57 -0400
Steven Rostedt <rostedt@...dmis.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;
 };