[PATCH] mm: vmscan: fix typo in isolating lru pages

[PATCH] mm: vmscan: fix typo in isolating lru pages

[Hillf Danton]

It is not the tag page but the cursor page that we should process, and it looks
a typo.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
---

--- a/mm/vmscan.c	Thu Dec 29 20:20:16 2011
+++ b/mm/vmscan.c	Thu Dec 29 20:23:30 2011
@@ -1231,13 +1231,13 @@ static unsigned long isolate_lru_pages(u

 				mem_cgroup_lru_del(cursor_page);
 				list_move(&cursor_page->lru, dst);
-				isolated_pages = hpage_nr_pages(page);
+				isolated_pages = hpage_nr_pages(cursor_page);
 				nr_taken += isolated_pages;
 				nr_lumpy_taken += isolated_pages;
 				if (PageDirty(cursor_page))
 					nr_lumpy_dirty += isolated_pages;
 				scan++;
-				pfn += isolated_pages-1;
+				pfn += isolated_pages - 1;
 			} else {
 				/*
 				 * Check if the page is freed already.

Re: [PATCH] mm: vmscan: fix typo in isolating lru pages

[KOSAKI Motohiro]

(12/29/11 7:38 AM), Hillf Danton wrote:
> It is not the tag page but the cursor page that we should process, and it looks
> a typo.
>
> Signed-off-by: Hillf Danton<dhillf@gmail.com>
> Cc: Michal Hocko<mhocko@suse.cz>
> Cc: KAMEZAWA Hiroyuki<kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Andrew Morton<akpm@linux-foundation.org>
> Cc: David Rientjes<rientjes@google.com>
> Cc: Hugh Dickins<hughd@google.com>
> ---
>
> --- a/mm/vmscan.c	Thu Dec 29 20:20:16 2011
> +++ b/mm/vmscan.c	Thu Dec 29 20:23:30 2011
> @@ -1231,13 +1231,13 @@ static unsigned long isolate_lru_pages(u
>
>   				mem_cgroup_lru_del(cursor_page);
>   				list_move(&cursor_page->lru, dst);
> -				isolated_pages = hpage_nr_pages(page);
> +				isolated_pages = hpage_nr_pages(cursor_page);
>   				nr_taken += isolated_pages;
>   				nr_lumpy_taken += isolated_pages;
>   				if (PageDirty(cursor_page))
>   					nr_lumpy_dirty += isolated_pages;
>   				scan++;
> -				pfn += isolated_pages-1;
> +				pfn += isolated_pages - 1;
>   			} else {
>   				/*
>   				 * Check if the page is freed already.

Looks correct.

Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

Re: [PATCH] mm: vmscan: fix typo in isolating lru pages

[Andrew Morton]

On Thu, 29 Dec 2011 20:38:41 +0800
Hillf Danton <dhillf@gmail.com> wrote:

> It is not the tag page but the cursor page that we should process, and it looks
> a typo.
> 
> Signed-off-by: Hillf Danton <dhillf@gmail.com>
> Cc: Michal Hocko <mhocko@suse.cz>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Hugh Dickins <hughd@google.com>
> ---
> 
> --- a/mm/vmscan.c	Thu Dec 29 20:20:16 2011
> +++ b/mm/vmscan.c	Thu Dec 29 20:23:30 2011
> @@ -1231,13 +1231,13 @@ static unsigned long isolate_lru_pages(u
> 
>  				mem_cgroup_lru_del(cursor_page);
>  				list_move(&cursor_page->lru, dst);
> -				isolated_pages = hpage_nr_pages(page);
> +				isolated_pages = hpage_nr_pages(cursor_page);
>  				nr_taken += isolated_pages;
>  				nr_lumpy_taken += isolated_pages;
>  				if (PageDirty(cursor_page))
>  					nr_lumpy_dirty += isolated_pages;
>  				scan++;
> -				pfn += isolated_pages-1;
> +				pfn += isolated_pages - 1;
>  			} else {
>  				/*
>  				 * Check if the page is freed already.

This problem looks pretty benign in mainline.  But Andrea's "mm:
vmscan: check if we isolated a compound page during lumpy scan" came
along and uses isolated_pages rather a lot more, including using it to
advance across the pfn array.

I jiggled your patch to suit current mainline then reworked everything
else so we end up with this result.

Re: [PATCH] mm: vmscan: fix typo in isolating lru pages

[Hillf Danton]

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[-- Attachment #1: Type: text/plain; charset=UTF-8, Size: 2388 bytes --]

On Fri, Dec 30, 2011 at 7:07 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Thu, 29 Dec 2011 20:38:41 +0800
> Hillf Danton <dhillf@gmail.com> wrote:
>
>> It is not the tag page but the cursor page that we should process, and it looks
>> a typo.
>>
>> Signed-off-by: Hillf Danton <dhillf@gmail.com>
>> Cc: Michal Hocko <mhocko@suse.cz>
>> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: David Rientjes <rientjes@google.com>
>> Cc: Hugh Dickins <hughd@google.com>
>> ---
>>
>> --- a/mm/vmscan.c     Thu Dec 29 20:20:16 2011
>> +++ b/mm/vmscan.c     Thu Dec 29 20:23:30 2011
>> @@ -1231,13 +1231,13 @@ static unsigned long isolate_lru_pages(u
>>
>>                               mem_cgroup_lru_del(cursor_page);
>>                               list_move(&cursor_page->lru, dst);
>> -                             isolated_pages = hpage_nr_pages(page);
>> +                             isolated_pages = hpage_nr_pages(cursor_page);
>>                               nr_taken += isolated_pages;
>>                               nr_lumpy_taken += isolated_pages;
>>                               if (PageDirty(cursor_page))
>>                                       nr_lumpy_dirty += isolated_pages;
>>                               scan++;
>> -                             pfn += isolated_pages-1;
>> +                             pfn += isolated_pages - 1;
>>                       } else {
>>                               /*
>>                                * Check if the page is freed already.
>
> This problem looks pretty benign in mainline.  But Andrea's "mm:
> vmscan: check if we isolated a compound page during lumpy scan" came
> along and uses isolated_pages rather a lot more, including using it to
> advance across the pfn array.
>
> I jiggled your patch to suit current mainline then reworked everything
> else so we end up with this result.
>
Hi folks

Thanks for your comments, ack and nack, in 2011.

Happy New Year

Hillf Danton
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Re: [PATCH] mm: vmscan: fix typo in isolating lru pages

[KAMEZAWA Hiroyuki]

On Thu, 29 Dec 2011 20:38:41 +0800
Hillf Danton <dhillf@gmail.com> wrote:

> It is not the tag page but the cursor page that we should process, and it looks
> a typo.
> 
> Signed-off-by: Hillf Danton <dhillf@gmail.com>
> Cc: Michal Hocko <mhocko@suse.cz>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Hugh Dickins <hughd@google.com>

Nice.
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>