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From: Andrew Morton <akpm@linux-foundation.org>
To: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Nitin Gupta <ngupta@vflare.org>, Minchan Kim <minchan@kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Dan Magenheimer <dan.magenheimer@oracle.com>,
	Robert Jennings <rcj@linux.vnet.ibm.com>,
	Jenifer Hopper <jhopper@us.ibm.com>, Mel Gorman <mgorman@suse.de>,
	Johannes Weiner <jweiner@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Larry Woodman <lwoodman@redhat.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Dave Hansen <dave@sr71.net>, Joe Perches <joe@perches.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Cody P Schafer <cody@linux.vnet.ibm.com>,
	Hugh Dickens <hughd@google.com>,
	Paul Mackerras <paulus@samba.org>,
	Heesub Shin <heesub.shin@samsung.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	devel@driverdev.osuosl.org
Subject: Re: [PATCHv12 2/4] zbud: add to mm/
Date: Wed, 29 May 2013 13:48:35 -0700	[thread overview]
Message-ID: <20130529134835.58dd89774f47205da4a06202@linux-foundation.org> (raw)
In-Reply-To: <20130529204236.GD428@cerebellum>

On Wed, 29 May 2013 15:42:36 -0500 Seth Jennings <sjenning@linux.vnet.ibm.com> wrote:

> > > > I worry about any code which independently looks at the pageframe
> > > > tables and expects to find page struts there.  One example is probably
> > > > memory_failure() but there are probably others.
> > 
> > ^^ this, please.  It could be kinda fatal.
> 
> I'll look into this.
> 
> The expected behavior is that memory_failure() should handle zbud pages in the
> same way that it handles in-use slub/slab/slob pages and return -EBUSY.

memory_failure() is merely an example of a general problem: code which
reads from the memmap[] array and expects its elements to be of type
`struct page'.  Other examples might be memory hotplugging, memory leak
checkers etc.  I have vague memories of out-of-tree patches
(bigphysarea?) doing this as well.

It's a general problem to which we need a general solution.

WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Nitin Gupta <ngupta@vflare.org>, Minchan Kim <minchan@kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Dan Magenheimer <dan.magenheimer@oracle.com>,
	Robert Jennings <rcj@linux.vnet.ibm.com>,
	Jenifer Hopper <jhopper@us.ibm.com>, Mel Gorman <mgorman@suse.de>,
	Johannes Weiner <jweiner@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Larry Woodman <lwoodman@redhat.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Dave Hansen <dave@sr71.net>, Joe Perches <joe@perches.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Cody P Schafer <cody@linux.vnet.ibm.com>,
	Hugh Dickens <hughd@google.com>,
	Paul Mackerras <paulus@samba.org>,
	Heesub Shin <heesub.shin@samsung.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	devel@driverdev.osuosl.org
Subject: Re: [PATCHv12 2/4] zbud: add to mm/
Date: Wed, 29 May 2013 13:48:35 -0700	[thread overview]
Message-ID: <20130529134835.58dd89774f47205da4a06202@linux-foundation.org> (raw)
In-Reply-To: <20130529204236.GD428@cerebellum>

On Wed, 29 May 2013 15:42:36 -0500 Seth Jennings <sjenning@linux.vnet.ibm.com> wrote:

> > > > I worry about any code which independently looks at the pageframe
> > > > tables and expects to find page struts there.  One example is probably
> > > > memory_failure() but there are probably others.
> > 
> > ^^ this, please.  It could be kinda fatal.
> 
> I'll look into this.
> 
> The expected behavior is that memory_failure() should handle zbud pages in the
> same way that it handles in-use slub/slab/slob pages and return -EBUSY.

memory_failure() is merely an example of a general problem: code which
reads from the memmap[] array and expects its elements to be of type
`struct page'.  Other examples might be memory hotplugging, memory leak
checkers etc.  I have vague memories of out-of-tree patches
(bigphysarea?) doing this as well.

It's a general problem to which we need a general solution.

--
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  reply	other threads:[~2013-05-29 20:48 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-05-20 16:26 [PATCHv12 0/4] zswap: compressed swap caching Seth Jennings
2013-05-20 16:26 ` Seth Jennings
2013-05-20 16:26 ` [PATCHv12 1/4] debugfs: add get/set for atomic types Seth Jennings
2013-05-20 16:26   ` Seth Jennings
2013-05-29 17:42   ` Konrad Rzeszutek Wilk
2013-05-29 17:42     ` Konrad Rzeszutek Wilk
2013-05-20 16:26 ` [PATCHv12 2/4] zbud: add to mm/ Seth Jennings
2013-05-20 16:26   ` Seth Jennings
2013-05-21  3:37   ` Bob Liu
2013-05-21  3:37     ` Bob Liu
2013-05-28 21:59   ` Andrew Morton
2013-05-28 21:59     ` Andrew Morton
2013-05-29 15:45     ` Seth Jennings
2013-05-29 15:45       ` Seth Jennings
2013-05-29 18:34       ` Andrew Morton
2013-05-29 18:34         ` Andrew Morton
2013-05-29 20:42         ` Seth Jennings
2013-05-29 20:42           ` Seth Jennings
2013-05-29 20:48           ` Andrew Morton [this message]
2013-05-29 20:48             ` Andrew Morton
2013-05-29 21:09             ` Dan Magenheimer
2013-05-29 21:09               ` Dan Magenheimer
2013-05-29 21:29               ` Andrew Morton
2013-05-29 21:29                 ` Andrew Morton
2013-05-30 17:43                 ` Seth Jennings
2013-05-30 17:43                   ` Seth Jennings
2013-05-30 21:20                   ` Seth Jennings
2013-05-30 21:20                     ` Seth Jennings
2013-05-31  1:48                     ` Bob Liu
2013-05-31  1:48                       ` Bob Liu
2013-06-03 13:48                   ` Konrad Rzeszutek Wilk
2013-06-03 13:48                     ` Konrad Rzeszutek Wilk
2013-05-29 20:45         ` Seth Jennings
2013-05-29 20:45           ` Seth Jennings
2013-05-20 16:26 ` [PATCHv12 3/4] zswap: " Seth Jennings
2013-05-20 16:26   ` Seth Jennings
2013-05-21  3:31   ` Bob Liu
2013-05-21  3:31     ` Bob Liu
2013-05-28 21:59   ` Andrew Morton
2013-05-28 21:59     ` Andrew Morton
2013-05-29 14:57     ` Seth Jennings
2013-05-29 14:57       ` Seth Jennings
2013-05-29 18:29       ` Andrew Morton
2013-05-29 18:29         ` Andrew Morton
2013-05-29 19:50         ` Seth Jennings
2013-05-29 19:50           ` Seth Jennings
2013-05-29 19:57           ` Andrew Morton
2013-05-29 19:57             ` Andrew Morton
2013-05-29 21:08             ` Seth Jennings
2013-05-29 21:08               ` Seth Jennings
2013-05-29 21:16               ` Andrew Morton
2013-05-29 21:16                 ` Andrew Morton
2013-05-20 16:26 ` [PATCHv12 4/4] zswap: add documentation Seth Jennings
2013-05-20 16:26   ` Seth Jennings

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