[PATCH] mm, notifier: Fix early return case for new lockdep annotations

[John Hubbard]

On 9/6/19 10:47 AM, Daniel Vetter wrote:
> I missed that when extending the lockdep annotations to the
> nonblocking case.
> 
> I missed this while testing since in the i915 mmu notifiers is hitting
> a nice lockdep splat already before the point of going into oom killer
> mode :-/
> 
> Reported-by: syzbot+aaedc50d99a03250fe1f at syzkaller.appspotmail.com
> Fixes: d2b219ed03d4 ("mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end")
> Cc: Jason Gunthorpe <jgg at mellanox.com>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: "Jérôme Glisse" <jglisse at redhat.com>
> Cc: Ralph Campbell <rcampbell at nvidia.com>
> Cc: Jason Gunthorpe <jgg at ziepe.ca>
> Cc: Ira Weiny <ira.weiny at intel.com>
> Cc: Michal Hocko <mhocko at suse.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Sean Christopherson <sean.j.christopherson at intel.com>
> Cc: Jean-Philippe Brucker <jean-philippe at linaro.org>
> Cc: linux-mm at kvack.org
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  include/linux/mmu_notifier.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
> index 5a03417e5bf7..4edd98b06834 100644
> --- a/include/linux/mmu_notifier.h
> +++ b/include/linux/mmu_notifier.h
> @@ -356,13 +356,14 @@ mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
>  static inline int
>  mmu_notifier_invalidate_range_start_nonblock(struct mmu_notifier_range *range)
>  {
> +	int ret = 0;
>  	lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
>  	if (mm_has_notifiers(range->mm)) {
>  		range->flags &= ~MMU_NOTIFIER_RANGE_BLOCKABLE;
> -		return __mmu_notifier_invalidate_range_start(range);
> +		ret = __mmu_notifier_invalidate_range_start(range);
>  	}
>  	lock_map_release(&__mmu_notifier_invalidate_range_start_map);
> -	return 0;
> +	return ret;
>  }
>  
>  static inline void
> 

Reviewed-by: John Hubbard <jhubbard at nvidia.com>


thanks,
-- 
John Hubbard
NVIDIA