linux-kernel - Re: [PATCH -mm v8 2/7] hwpoison: use page_cgroup

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Date:	Wed, 15 Jul 2015 12:00:13 -0700
From:	Andres Lagar-Cavilla <andreslc@...gle.com>
To:	Vladimir Davydov <vdavydov@...allels.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Minchan Kim <minchan@...nel.org>,
	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>,
	Greg Thelen <gthelen@...gle.com>,
	Michel Lespinasse <walken@...gle.com>,
	David Rientjes <rientjes@...gle.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Jonathan Corbet <corbet@....net>, linux-api@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-mm@...ck.org,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -mm v8 2/7] hwpoison: use page_cgroup_ino for filtering by memcg

On Wed, Jul 15, 2015 at 6:54 AM, Vladimir Davydov
<vdavydov@...allels.com> wrote:
> Hwpoison allows to filter pages by memory cgroup ino. Currently, it
> calls try_get_mem_cgroup_from_page to obtain the cgroup from a page and
> then its ino using cgroup_ino, but now we have an apter method for that,
> page_cgroup_ino, so use it instead.
>
> Signed-off-by: Vladimir Davydov <vdavydov@...allels.com>

Reviewed-by: Andres Lagar-Cavilla <andreslc@...gle.com>

> ---
>  mm/hwpoison-inject.c |  5 +----
>  mm/memory-failure.c  | 16 ++--------------
>  2 files changed, 3 insertions(+), 18 deletions(-)
>
> diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
> index bf73ac17dad4..5015679014c1 100644
> --- a/mm/hwpoison-inject.c
> +++ b/mm/hwpoison-inject.c
> @@ -45,12 +45,9 @@ static int hwpoison_inject(void *data, u64 val)
>         /*
>          * do a racy check with elevated page count, to make sure PG_hwpoison
>          * will only be set for the targeted owner (or on a free page).
> -        * We temporarily take page lock for try_get_mem_cgroup_from_page().
>          * memory_failure() will redo the check reliably inside page lock.
>          */
> -       lock_page(hpage);
>         err = hwpoison_filter(hpage);
> -       unlock_page(hpage);
>         if (err)
>                 goto put_out;
>
> @@ -126,7 +123,7 @@ static int pfn_inject_init(void)
>         if (!dentry)
>                 goto fail;
>
> -#ifdef CONFIG_MEMCG_SWAP
> +#ifdef CONFIG_MEMCG
>         dentry = debugfs_create_u64("corrupt-filter-memcg", 0600,
>                                     hwpoison_dir, &hwpoison_filter_memcg);
>         if (!dentry)
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 1cf7f2988422..97005396a507 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -130,27 +130,15 @@ static int hwpoison_filter_flags(struct page *p)
>   * can only guarantee that the page either belongs to the memcg tasks, or is
>   * a freed page.
>   */
> -#ifdef CONFIG_MEMCG_SWAP
> +#ifdef CONFIG_MEMCG
>  u64 hwpoison_filter_memcg;
>  EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
>  static int hwpoison_filter_task(struct page *p)
>  {
> -       struct mem_cgroup *mem;
> -       struct cgroup_subsys_state *css;
> -       unsigned long ino;
> -
>         if (!hwpoison_filter_memcg)
>                 return 0;
>
> -       mem = try_get_mem_cgroup_from_page(p);
> -       if (!mem)
> -               return -EINVAL;
> -
> -       css = mem_cgroup_css(mem);
> -       ino = cgroup_ino(css->cgroup);
> -       css_put(css);
> -
> -       if (ino != hwpoison_filter_memcg)
> +       if (page_cgroup_ino(p) != hwpoison_filter_memcg)
>                 return -EINVAL;
>
>         return 0;
> --
> 2.1.4
>



-- 
Andres Lagar-Cavilla | Google Kernel Team | andreslc@...gle.com
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