On Mon, Sep 09, 2019 at 12:10:16AM -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.
>
> Instead, allocate pages directly. Given currently page->objects has
> 15 bits, we only need 1 page. We may waste some memory but we only do
> so when slub debug is on.
>
> 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>
Looks sane to me:
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
--
Kirill A. Shutemov
