linux-kernel - Re: [resend][PATCH -mm] split_lru: fix pagevec_move

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Date:	Wed, 2 Jul 2008 14:00:25 +0900
From:	"MinChan Kim" <minchan.kim@...il.com>
To:	"KOSAKI Motohiro" <kosaki.motohiro@...fujitsu.com>
Cc:	"Rik van Riel" <riel@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	"Lee Schermerhorn" <Lee.Schermerhorn@...com>,
	"Andrew Morton" <akpm@...ux-foundation.org>
Subject: Re: [resend][PATCH -mm] split_lru: fix pagevec_move_tail() doesn't treat unevictable page

On Wed, Jul 2, 2008 at 12:30 PM, KOSAKI Motohiro
<kosaki.motohiro@...fujitsu.com> wrote:
> Hi Kim-san,
>
>> Hi, Rik and Kosaki-san
>>
>> I want to know exact race situation for remaining git log.
>> As you know, git log is important for me who is newbie to understand source
>>
>> There are many possibility in this race problem.
>>
>> Did you use hugepage in this test ?
>> I think that If you used hugepage, it seems to happen following race.
>
> I don't use hugepage. but use SYSV-shmem.
> so following scenario is very reasonable.

It is not reasonable if you don't use hugepage.
That's because file's address_space is still unevictable.
Am I missing your point?

I think following case is more reasonable rather than it,
Please, Let you review this scenario.
---

CPU1							CPU2

shrink_[in]active_list
cull_unevictable_page
putback_lru_page
TestClearPageUnevicetable
						rotate_reclaimable_page
						!PageUnevictable(page)
add_page_to_unevictable_list
						pagevec_move_tail



> OK.
> I resend my patch with following description.
>
>
>>
>> --------------
>>
>> CPU1                                                           CPU2
>>
>> shm_unlock
>> scan_mapping_unevictable_pages
>> check_move_unevictable_page
>> ClearPageUnevictable                                 rotate_reclaimable_page
>>
>> PageUnevictable(page) return 0
>> SetPageUnevictable
>> list_move(LRU_UNEVICTABLE)
>>
>> local_irq_save
>>
>> pagevec_move_tail
>>
>> Do you think it is possible ?
>
>
>



-- 
Kinds regards,
MinChan Kim
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