linux-kernel - Re: [PATCH] swap: redirty page if page write fails on swap file

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Date:	Fri, 03 May 2013 11:12:44 +0200
From:	Jerome Marchand <jmarchan@...hat.com>
To:	Simon Jeons <simon.jeons@...il.com>
CC:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Mel Gorman <mgorman@...e.de>
Subject: Re: [PATCH] swap: redirty page if page write fails on swap file

On 05/01/2013 09:39 AM, Simon Jeons wrote:
> Ping, ;-)
> On 04/18/2013 08:13 AM, Simon Jeons wrote:
>> Hi Jerome,
>> On 04/17/2013 08:11 PM, Jerome Marchand wrote:
>>> Since commit 62c230b, swap_writepage() calls direct_IO on swap files.
>>> However, in that case page isn't redirtied if I/O fails, and is 
>>> therefore
>>> handled afterwards as if it has been successfully written to the swap
>>> file, leading to memory corruption when the page is eventually swapped
>>> back in.
>>> This patch sets the page dirty when direct_IO() fails. It fixes a memory
>>
>> If swapfile has related page cache which cached swapfile in memory? It 
>> is not necessary, correct?

I'm not sure I understand the question. What I can tell you is that it is 
necessary if the swapfile is located on a fs that uses swap_activate (only
NFS so far). Other swap file hasn't been impacted by commit 62c230b.

>>
>>> corruption that happened while using swap-over-NFS.
>>>
>>> Signed-off-by: Jerome Marchand <jmarchan@...hat.com>
>>> ---
>>>   mm/page_io.c |    2 ++
>>>   1 files changed, 2 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/mm/page_io.c b/mm/page_io.c
>>> index 78eee32..04ca00d 100644
>>> --- a/mm/page_io.c
>>> +++ b/mm/page_io.c
>>> @@ -222,6 +222,8 @@ int swap_writepage(struct page *page, struct 
>>> writeback_control *wbc)
>>>           if (ret == PAGE_SIZE) {
>>>               count_vm_event(PSWPOUT);
>>>               ret = 0;
>>> +        } else {
>>> +            set_page_dirty(page);
>>>           }
>>>           return ret;
>>>       }
>>>
>>> -- 
>>> To unsubscribe, send a message with 'unsubscribe linux-mm' in
>>> the body to majordomo@...ck.org.  For more info on Linux MM,
>>> see: http://www.linux-mm.org/ .
>>> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
>>
> 

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