diff mbox series

NFSv4.2: fix failure to unregister shrinker

Message ID 20201021143415.GA27122@fieldses.org
State New
Headers show
Series NFSv4.2: fix failure to unregister shrinker | expand

Commit Message

J. Bruce Fields Oct. 21, 2020, 2:34 p.m. UTC
From: "J. Bruce Fields" <bfields@redhat.com>

We forgot to unregister the nfs4_xattr_large_entry_shrinker.

That leaves the global list of shrinkers corrupted after unload of the
nfs module, after which possibly unrelated code that calls
register_shrinker() or unregister_shrinker() gets a BUG() with
"supervisor write access in kernel mode".

And similarly for the nfs4_xattr_large_entry_lru.

Reported-by: Kris Karas <bugs-a17@moonlit-rail.com>
Tested-By: Kris Karas <bugs-a17@moonlit-rail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/nfs/nfs42xattr.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

J. Bruce Fields Nov. 12, 2020, 2:03 p.m. UTC | #1
Looks like this patch got lost, do you need me to resend?

I should also have added a stable cc and a

	Fixes: 95ad37f90c33 "NFSv4.2: add client side xattr caching."

--b.

On Wed, Oct 21, 2020 at 10:34:15AM -0400, bfields wrote:
> From: "J. Bruce Fields" <bfields@redhat.com>
> 
> We forgot to unregister the nfs4_xattr_large_entry_shrinker.
> 
> That leaves the global list of shrinkers corrupted after unload of the
> nfs module, after which possibly unrelated code that calls
> register_shrinker() or unregister_shrinker() gets a BUG() with
> "supervisor write access in kernel mode".
> 
> And similarly for the nfs4_xattr_large_entry_lru.
> 
> Reported-by: Kris Karas <bugs-a17@moonlit-rail.com>
> Tested-By: Kris Karas <bugs-a17@moonlit-rail.com>
> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
> ---
>  fs/nfs/nfs42xattr.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/nfs/nfs42xattr.c b/fs/nfs/nfs42xattr.c
> index 86777996cfec..55b44a42d625 100644
> --- a/fs/nfs/nfs42xattr.c
> +++ b/fs/nfs/nfs42xattr.c
> @@ -1048,8 +1048,10 @@ int __init nfs4_xattr_cache_init(void)
>  
>  void nfs4_xattr_cache_exit(void)
>  {
> +	unregister_shrinker(&nfs4_xattr_large_entry_shrinker);
>  	unregister_shrinker(&nfs4_xattr_entry_shrinker);
>  	unregister_shrinker(&nfs4_xattr_cache_shrinker);
> +	list_lru_destroy(&nfs4_xattr_large_entry_lru);
>  	list_lru_destroy(&nfs4_xattr_entry_lru);
>  	list_lru_destroy(&nfs4_xattr_cache_lru);
>  	kmem_cache_destroy(nfs4_xattr_cache_cachep);
> -- 
> 2.26.2
>
Anna Schumaker Nov. 12, 2020, 2:07 p.m. UTC | #2
No need to resend! I'll make sure the fixes & cc line get added to the commit

On Thu, Nov 12, 2020 at 9:03 AM J. Bruce Fields <bfields@fieldses.org> wrote:
>
> Looks like this patch got lost, do you need me to resend?
>
> I should also have added a stable cc and a
>
>         Fixes: 95ad37f90c33 "NFSv4.2: add client side xattr caching."
>
> --b.
>
> On Wed, Oct 21, 2020 at 10:34:15AM -0400, bfields wrote:
> > From: "J. Bruce Fields" <bfields@redhat.com>
> >
> > We forgot to unregister the nfs4_xattr_large_entry_shrinker.
> >
> > That leaves the global list of shrinkers corrupted after unload of the
> > nfs module, after which possibly unrelated code that calls
> > register_shrinker() or unregister_shrinker() gets a BUG() with
> > "supervisor write access in kernel mode".
> >
> > And similarly for the nfs4_xattr_large_entry_lru.
> >
> > Reported-by: Kris Karas <bugs-a17@moonlit-rail.com>
> > Tested-By: Kris Karas <bugs-a17@moonlit-rail.com>
> > Signed-off-by: J. Bruce Fields <bfields@redhat.com>
> > ---
> >  fs/nfs/nfs42xattr.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/fs/nfs/nfs42xattr.c b/fs/nfs/nfs42xattr.c
> > index 86777996cfec..55b44a42d625 100644
> > --- a/fs/nfs/nfs42xattr.c
> > +++ b/fs/nfs/nfs42xattr.c
> > @@ -1048,8 +1048,10 @@ int __init nfs4_xattr_cache_init(void)
> >
> >  void nfs4_xattr_cache_exit(void)
> >  {
> > +     unregister_shrinker(&nfs4_xattr_large_entry_shrinker);
> >       unregister_shrinker(&nfs4_xattr_entry_shrinker);
> >       unregister_shrinker(&nfs4_xattr_cache_shrinker);
> > +     list_lru_destroy(&nfs4_xattr_large_entry_lru);
> >       list_lru_destroy(&nfs4_xattr_entry_lru);
> >       list_lru_destroy(&nfs4_xattr_cache_lru);
> >       kmem_cache_destroy(nfs4_xattr_cache_cachep);
> > --
> > 2.26.2
> >
diff mbox series

Patch

diff --git a/fs/nfs/nfs42xattr.c b/fs/nfs/nfs42xattr.c
index 86777996cfec..55b44a42d625 100644
--- a/fs/nfs/nfs42xattr.c
+++ b/fs/nfs/nfs42xattr.c
@@ -1048,8 +1048,10 @@  int __init nfs4_xattr_cache_init(void)
 
 void nfs4_xattr_cache_exit(void)
 {
+	unregister_shrinker(&nfs4_xattr_large_entry_shrinker);
 	unregister_shrinker(&nfs4_xattr_entry_shrinker);
 	unregister_shrinker(&nfs4_xattr_cache_shrinker);
+	list_lru_destroy(&nfs4_xattr_large_entry_lru);
 	list_lru_destroy(&nfs4_xattr_entry_lru);
 	list_lru_destroy(&nfs4_xattr_cache_lru);
 	kmem_cache_destroy(nfs4_xattr_cache_cachep);