Re: [PATCH] kernfs: Move faulting copy_user operations outside of the mutex

From: Tejun Heo
Date: Thu Mar 31 2016 - 12:49:21 EST

On Thu, Mar 31, 2016 at 11:45:06AM +0100, Chris Wilson wrote:
> A fault in a user provided buffer may lead anywhere, and lockdep warns
> that we have a potential deadlock between the mm->mmap_sem and the
> kernfs file mutex:
> Reported-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Bugzilla:
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: NeilBrown <neilb@xxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx

Acked-by: Tejun Heo <tj@xxxxxxxxxx>