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Subject: Re: [PATCH] mm, notifier: Fix early return case for new lockdep
 annotations
To:     Daniel Vetter <daniel.vetter@ffwll.ch>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     DRI Development <dri-devel@lists.freedesktop.org>,
        syzbot+aaedc50d99a03250fe1f@syzkaller.appspotmail.com,
        Jason Gunthorpe <jgg@mellanox.com>,
        Daniel Vetter <daniel.vetter@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Ira Weiny <ira.weiny@intel.com>,
        Michal Hocko <mhocko@suse.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        linux-mm@kvack.org
References: <20190906174730.22462-1-daniel.vetter@ffwll.ch>
From:   David Hildenbrand <david@redhat.com>
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Organization: Red Hat GmbH
Message-ID: <8fec380a-7dd1-846a-598a-90ec6f67eb43@redhat.com>
Date:   Mon, 9 Sep 2019 10:22:54 +0200
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On 06.09.19 19:47, 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@syzkaller.appspotmail.com
> Fixes: d2b219ed03d4 ("mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end")
> Cc: Jason Gunthorpe <jgg@mellanox.com>
> Cc: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: "Jérôme Glisse" <jglisse@redhat.com>
> Cc: Ralph Campbell <rcampbell@nvidia.com>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Cc: linux-mm@kvack.org
> Signed-off-by: Daniel Vetter <daniel.vetter@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: David Hildenbrand <david@redhat.com>

-- 

Thanks,

David / dhildenb