linux-kernel - Re: [v3 PATCH 1/7] mm: khugepaged: check THP flag in hugepage_vma

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Message-ID: <85932a40-a05b-3610-5836-aab36d2664f0@huawei.com>
Date:   Fri, 10 Jun 2022 15:09:35 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Yang Shi <shy828301@...il.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <vbabka@...e.cz>, <kirill.shutemov@...ux.intel.com>,
        <willy@...radead.org>, <akpm@...ux-foundation.org>
Subject: Re: [v3 PATCH 1/7] mm: khugepaged: check THP flag in
 hugepage_vma_check()

On 2022/6/7 5:44, Yang Shi wrote:
> Currently the THP flag check in hugepage_vma_check() will fallthrough if
> the flag is NEVER and VM_HUGEPAGE is set.  This is not a problem for now
> since all the callers have the flag checked before or can't be invoked if
> the flag is NEVER.
> 
> However, the following patch will call hugepage_vma_check() in more
> places, for example, page fault, so this flag must be checked in
> hugepge_vma_check().
> 
> Signed-off-by: Yang Shi <shy828301@...il.com>

Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>

Thanks!

> ---
>  mm/khugepaged.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 671ac7800e53..84b9cf4b9be9 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -458,6 +458,9 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
>  	if (shmem_file(vma->vm_file))
>  		return shmem_huge_enabled(vma);
>  
> +	if (!khugepaged_enabled())
> +		return false;
> +
>  	/* THP settings require madvise. */
>  	if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
>  		return false;
>