linux-kernel - Re: [RESEND PATCH v2] thp: Remove unused vma parameter from khugepaged_alloc

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Message-ID: <563A229A.4030000@suse.cz>
Date:	Wed, 4 Nov 2015 16:22:02 +0100
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Aaron Tomlin <atomlin@...hat.com>, akpm@...ux-foundation.org
Cc:	riel@...hat.com, lwoodman@...hat.com, aarcange@...hat.com,
	kirill.shutemov@...ux.intel.com, mgorman@...e.de,
	willy@...ux.intel.com, aneesh.kumar@...ux.vnet.ibm.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v2] thp: Remove unused vma parameter from
 khugepaged_alloc_page

On 11/04/2015 01:48 PM, Aaron Tomlin wrote:
> Resending due to incomplete subject.
>
> Changes since v2:
>
>   - Fixed incorrect commit message
>
> The "vma" parameter to khugepaged_alloc_page() is unused.
> It has to remain unused or the drop read lock 'map_sem' optimisation
> introduce by commit 8b1645685acf ("mm, THP: don't hold mmap_sem in
> khugepaged when allocating THP") wouldn't be safe. So let's remove it.
>
> Signed-off-by: Aaron Tomlin <atomlin@...hat.com>

Pretty sure the compiler inlines it away anyway, but sure, why not.
Acked-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>   mm/huge_memory.c | 8 +++-----
>   1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index bbac913..490fa81 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2413,8 +2413,7 @@ static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
>
>   static struct page *
>   khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
> -		       struct vm_area_struct *vma, unsigned long address,
> -		       int node)
> +		       unsigned long address, int node)
>   {
>   	VM_BUG_ON_PAGE(*hpage, *hpage);
>
> @@ -2481,8 +2480,7 @@ static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
>
>   static struct page *
>   khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
> -		       struct vm_area_struct *vma, unsigned long address,
> -		       int node)
> +		       unsigned long address, int node)
>   {
>   	up_read(&mm->mmap_sem);
>   	VM_BUG_ON(!*hpage);
> @@ -2530,7 +2528,7 @@ static void collapse_huge_page(struct mm_struct *mm,
>   		__GFP_THISNODE;
>
>   	/* release the mmap_sem read lock. */
> -	new_page = khugepaged_alloc_page(hpage, gfp, mm, vma, address, node);
> +	new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node);
>   	if (!new_page)
>   		return;
>
>

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