Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210420002821.2749748-1-jane.chu@oracle.com>
In-Reply-To: <20210420002821.2749748-1-jane.chu@oracle.com>
From:   Dan Williams <dan.j.williams@intel.com>
Date:   Mon, 19 Apr 2021 17:33:10 -0700
Message-ID: <CAPcyv4j-JANFd_b0x8fPd3=OsfGk+SDmdSZhMVyrQowex5r6KQ@mail.gmail.com>
Subject: Re: [PATCH] mm/memory-failure: unecessary amount of unmapping
To:     Jane Chu <jane.chu@oracle.com>
Cc:     Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux MM <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Apr 19, 2021 at 5:28 PM Jane Chu <jane.chu@oracle.com> wrote:
>
> It appears that unmap_mapping_range() actually takes a 'size' as its
> third argument rather than a location,

Indeed.

> the current calling fashion
> causes unecessary amount of unmapping to occur.

s/unecessary/unnecessary/

>
> Fixes: 6100e34b2526e ("mm, memory_failure: Teach memory_failure() about dev_pagemap pages")
> Signed-off-by: Jane Chu <jane.chu@oracle.com>

Other than changelog fixup, looks good.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

> ---
>  mm/memory-failure.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index f7ed9559d494..85ad98c00fd9 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1368,7 +1368,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
>                  * communicated in siginfo, see kill_proc()
>                  */
>                 start = (page->index << PAGE_SHIFT) & ~(size - 1);
> -               unmap_mapping_range(page->mapping, start, start + size, 0);
> +               unmap_mapping_range(page->mapping, start, size, 0);
>         }
>         kill_procs(&tokill, flags & MF_MUST_KILL, !unmap_success, pfn, flags);
>         rc = 0;
> --
> 2.18.4
>