linux-kernel - Re: [PATCH 3/3] mm: thp: split_huge_pmd

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Message-ID: <20160506173347.GB9879@node.shutemov.name>
Date:	Fri, 6 May 2016 20:33:47 +0300
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Andrea Arcangeli <aarcange@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Alex Williamson <alex.williamson@...hat.com>
Subject: Re: [PATCH 3/3] mm: thp: split_huge_pmd_address() comment improvement

On Fri, May 06, 2016 at 05:04:00PM +0200, Andrea Arcangeli wrote:
> Comment is partly wrong, this improves it by including the case of
> split_huge_pmd_address() called by try_to_unmap_one if
> TTU_SPLIT_HUGE_PMD is set.
> 
> Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

> ---
>  mm/huge_memory.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 9086793..1fbe13d 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -3031,8 +3031,10 @@ void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
>  		return;
>  
>  	/*
> -	 * Caller holds the mmap_sem write mode, so a huge pmd cannot
> -	 * materialize from under us.
> +	 * Caller holds the mmap_sem write mode or the anon_vma lock,
> +	 * so a huge pmd cannot materialize from under us (khugepaged
> +	 * holds both the mmap_sem write mode and the anon_vma lock
> +	 * write mode).
>  	 */
>  	__split_huge_pmd(vma, pmd, address, freeze);
>  }

-- 
 Kirill A. Shutemov