Date: Tue, 21 Jul 2015 16:34:12 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Vladimir Davydov <vdavydov@parallels.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>,
        Minchan Kim <minchan@kernel.org>,
        Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>,
        Greg Thelen <gthelen@google.com>,
        Michel Lespinasse <walken@google.com>,
        David Rientjes <rientjes@google.com>,
        Pavel Emelyanov <xemul@parallels.com>,
        Cyrill Gorcunov <gorcunov@openvz.org>,
        Jonathan Corbet <corbet@lwn.net>, <linux-api@vger.kernel.org>,
        <linux-doc@vger.kernel.org>, <linux-mm@kvack.org>,
        <cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -mm v9 2/8] hwpoison: use page_cgroup_ino for filtering
 by memcg
Message-Id: <20150721163412.1b44e77f5ac3b742734d1ce6@linux-foundation.org>
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References: <cover.1437303956.git.vdavydov@parallels.com>
	<94215634d13582d2a1453686d6cc6b1a59b07d2a.1437303956.git.vdavydov@parallels.com>
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On Sun, 19 Jul 2015 15:31:11 +0300 Vladimir Davydov <vdavydov@parallels.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.

I assume "an apter" was supposed to be "a helper"?

> --- 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)

Confused.  We're changing the conditions under which this debugfs file
is created.  Is this a typo or some unchangelogged thing or what?


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