linux-kernel - Re: [PATCH] mm/madvise: reduce code duplication in error handling paths

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Message-ID: <1944499597.6210303.1564641818536.JavaMail.zimbra@redhat.com>
Date:   Thu, 1 Aug 2019 02:43:38 -0400 (EDT)
From:   Pankaj Gupta <pagupta@...hat.com>
To:     Mike Rapoport <rppt@...ux.ibm.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/madvise: reduce code duplication in error handling
 paths


> 
> The madvise_behavior() function converts -ENOMEM to -EAGAIN in several
> places using identical code.
> 
> Move that code to a common error handling path.
> 
> No functional changes.
> 
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
> ---
>  mm/madvise.c | 52 ++++++++++++++++------------------------------------
>  1 file changed, 16 insertions(+), 36 deletions(-)
> 
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 968df3a..55d78fd 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -105,28 +105,14 @@ static long madvise_behavior(struct vm_area_struct
> *vma,
>  	case MADV_MERGEABLE:
>  	case MADV_UNMERGEABLE:
>  		error = ksm_madvise(vma, start, end, behavior, &new_flags);
> -		if (error) {
> -			/*
> -			 * madvise() returns EAGAIN if kernel resources, such as
> -			 * slab, are temporarily unavailable.
> -			 */
> -			if (error == -ENOMEM)
> -				error = -EAGAIN;
> -			goto out;
> -		}
> +		if (error)
> +			goto out_convert_errno;
>  		break;
>  	case MADV_HUGEPAGE:
>  	case MADV_NOHUGEPAGE:
>  		error = hugepage_madvise(vma, &new_flags, behavior);
> -		if (error) {
> -			/*
> -			 * madvise() returns EAGAIN if kernel resources, such as
> -			 * slab, are temporarily unavailable.
> -			 */
> -			if (error == -ENOMEM)
> -				error = -EAGAIN;
> -			goto out;
> -		}
> +		if (error)
> +			goto out_convert_errno;
>  		break;
>  	}
>  
> @@ -152,15 +138,8 @@ static long madvise_behavior(struct vm_area_struct *vma,
>  			goto out;
>  		}
>  		error = __split_vma(mm, vma, start, 1);
> -		if (error) {
> -			/*
> -			 * madvise() returns EAGAIN if kernel resources, such as
> -			 * slab, are temporarily unavailable.
> -			 */
> -			if (error == -ENOMEM)
> -				error = -EAGAIN;
> -			goto out;
> -		}
> +		if (error)
> +			goto out_convert_errno;
>  	}
>  
>  	if (end != vma->vm_end) {
> @@ -169,15 +148,8 @@ static long madvise_behavior(struct vm_area_struct *vma,
>  			goto out;
>  		}
>  		error = __split_vma(mm, vma, end, 0);
> -		if (error) {
> -			/*
> -			 * madvise() returns EAGAIN if kernel resources, such as
> -			 * slab, are temporarily unavailable.
> -			 */
> -			if (error == -ENOMEM)
> -				error = -EAGAIN;
> -			goto out;
> -		}
> +		if (error)
> +			goto out_convert_errno;
>  	}
>  
>  success:
> @@ -185,6 +157,14 @@ static long madvise_behavior(struct vm_area_struct *vma,
>  	 * vm_flags is protected by the mmap_sem held in write mode.
>  	 */
>  	vma->vm_flags = new_flags;
> +
> +out_convert_errno:
> +	/*
> +	 * madvise() returns EAGAIN if kernel resources, such as
> +	 * slab, are temporarily unavailable.
> +	 */
> +	if (error == -ENOMEM)
> +		error = -EAGAIN;
>  out:
>  	return error;
>  }

looks good.

Acked-by: Pankaj Gupta <pagupta@...hat.com>

> --
> 2.7.4
> 
>