linux-kernel - Re: [BUGFIX][PATCH] fix wrong lru rotate back at lumpty reclaim

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Message-ID: <7ca0521d9b798ef8b56212e5b17ea713.squirrel@webmail-b.css.fujitsu.com>
Date:	Tue, 9 Jun 2009 20:47:45 +0900 (JST)
From:	"KAMEZAWA Hiroyuki" <kamezawa.hiroyu@...fujitsu.com>
To:	"Minchan Kim" <minchan.kim@...il.com>
Cc:	"KAMEZAWA Hiroyuki" <kamezawa.hiroyu@...fujitsu.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"kosaki.motohiro@...fujitsu.com" <kosaki.motohiro@...fujitsu.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	riel@...hat.com
Subject: Re: [BUGFIX][PATCH] fix wrong lru rotate back at lumpty reclaim

Minchan Kim wrote:

> I mean follow as
>  908         /*
>  909          * Attempt to take all pages in the order aligned region
>  910          * surrounding the tag page.  Only take those pages of
>  911          * the same active state as that tag page.  We may safely
>  912          * round the target page pfn down to the requested order
>  913          * as the mem_map is guarenteed valid out to MAX_ORDER,
>  914          * where that page is in a different zone we will detect
>  915          * it from its zone id and abort this block scan.
>  916          */
>  917         zone_id = page_zone_id(page);
>
But what this code really do is.
==
931                         /* Check that we have not crossed a zone
boundary. */
 932                         if (unlikely(page_zone_id(cursor_page) !=
zone_id))
 933                                 continue;
==
continue. I think this should be "break"
I wonder what "This block scan" means is "scanning this aligned block".

But I think the whoe code is not written as commented.

>
>>> If I understand it properly , don't we add goto phrase ?
>>>
>> No.
>
> If it is so, the break also is meaningless.
>
yes. I'll remove it. But need to add "exit from for loop" logic again.

I'm sorry that the wrong logic of this loop was out of my sight.
I'll review and rewrite this part all, tomorrow.

Thanks,
-Kame

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