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Date: Mon, 28 Mar 2016 11:42:05 -0700 (PDT)
From: Hugh Dickins <hughd@google.com>
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To: "Kirill A. Shutemov" <kirill@shutemov.name>
cc: Hugh Dickins <hughd@google.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@intel.com>, Vlastimil Babka <vbabka@suse.cz>,
        Christoph Lameter <cl@gentwo.org>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Jerome Marchand <jmarchan@redhat.com>, Yang Shi <yang.shi@linaro.org>,
        Sasha Levin <sasha.levin@oracle.com>, Ning Qu <quning@gmail.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCHv4 00/25] THP-enabled tmpfs/shmem
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On Mon, 28 Mar 2016, Kirill A. Shutemov wrote:
> 
> I think I found it. I have refcounting screwed up in faultaround.
> 
> This should fix the problem:

Yes, this fixes it for me - thanks.

Hugh

> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 94c097ec08e7..1325bb4568d1 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2292,19 +2292,18 @@ repeat:
>  		if (fe->pte)
>  			fe->pte += iter.index - last_pgoff;
>  		last_pgoff = iter.index;
> -		alloc_set_pte(fe, NULL, page);
> +		if (alloc_set_pte(fe, NULL, page))
> +			goto unlock;
>  		unlock_page(page);
> -		/* Huge page is mapped? No need to proceed. */
> -		if (pmd_trans_huge(*fe->pmd))
> -			break;
> -		/* Failed to setup page table? */
> -		VM_BUG_ON(!fe->pte);
>  		goto next;
>  unlock:
>  		unlock_page(page);
>  skip:
>  		page_cache_release(page);
>  next:
> +		/* Huge page is mapped? No need to proceed. */
> +		if (pmd_trans_huge(*fe->pmd))
> +			break;
>  		if (iter.index == end_pgoff)
>  			break;
>  	}
> -- 
>  Kirill A. Shutemov