On Wed, Sep 11, 2019 at 08:31:10PM -0600, Yu Zhao wrote:
> If we are already under list_lock, don't call kmalloc(). Otherwise we
> will run into deadlock because kmalloc() also tries to grab the same
> lock.
>
> Fixing the problem by using a static bitmap instead.
>
> WARNING: possible recursive locking detected
> --------------------------------------------
> mount-encrypted/4921 is trying to acquire lock:
> (&(&n->list_lock)->rlock){-.-.}, at: ___slab_alloc+0x104/0x437
>
> but task is already holding lock:
> (&(&n->list_lock)->rlock){-.-.}, at: __kmem_cache_shutdown+0x81/0x3cb
>
> other info that might help us debug this:
> Possible unsafe locking scenario:
>
> CPU0
> ----
> lock(&(&n->list_lock)->rlock);
> lock(&(&n->list_lock)->rlock);
>
> *** DEADLOCK ***
>
> Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
--
Kirill A. Shutemov
