Re: [patch] x86, pat: freeing invalid memtype messages

[Xiaotian Feng]

On 06/18/2010 12:17 AM, Marcin Slusarz wrote:
> On Thu, Jun 17, 2010 at 03:45:59PM +0200, Dan Carpenter wrote:
> > Commit 20413f27163 "x86, pat: Fix memory leak in free_memtype" added an
> > error message in free_memtype() if rbt_memtype_erase() returns NULL.
> > The problem is that if CONFIG_X86_PAT is enabled, we use a different
> > implimentation of rbt_memtype_erase() that always returns NULL.
> >
> > I've modified rbt_memtype_erase() to return an ERR_PTR() on errors and
> > made free_memtype() check for that instead.
> >
> > Addresses:  https://bugzilla.kernel.org/show_bug.cgi?id=16205
> >
> > Signed-off-by: Dan Carpenter<error27@xxxxxxxxx>
>
> This patch is probably ok, but it does not address my bug.
> I have CONFIG_X86_PAT=y, so rbt_memtype_erase does not always return NULL.

Could you please try boot with kernel parameter "debugpat", and
show me the output of reserve_memtype/free_memtype ?

> > diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
> > index acc15b2..81b7735 100644
> > --- a/arch/x86/mm/pat.c
> > +++ b/arch/x86/mm/pat.c
> > @@ -359,10 +359,10 @@ int free_memtype(u64 start, u64 end)
> >   	entry = rbt_memtype_erase(start, end);
> >   	spin_unlock(&memtype_lock);
> >
> > -	if (!entry) {
> > +	if (IS_ERR(entry)) {
> >   		printk(KERN_INFO "%s:%d freeing invalid memtype %Lx-%Lx\n",
> >   			current->comm, current->pid, start, end);
> > -		return -EINVAL;
> > +		return PTR_ERR(entry);
> >   	}
> >
> >   	kfree(entry);
> > diff --git a/arch/x86/mm/pat_rbtree.c b/arch/x86/mm/pat_rbtree.c
> > index f537087..90e5cbe 100644
> > --- a/arch/x86/mm/pat_rbtree.c
> > +++ b/arch/x86/mm/pat_rbtree.c
> > @@ -236,8 +236,10 @@ struct memtype *rbt_memtype_erase(u64 start, u64 end)
> >   	struct memtype *data;
> >
> >   	data = memtype_rb_exact_match(&memtype_rbroot, start, end);
> > -	if (!data)
> > +	if (!data) {
> > +		data = ERR_PTR(-EINVAL);
> >   		goto out;
> > +	}
> >
> >   	rb_erase(&data->rb,&memtype_rbroot);
> >   out:

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