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From: Ding Hui <dinghui@sangfor.com.cn>
To: "HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>
Cc: "david@redhat.com" <david@redhat.com>,
	"osalvador@suse.de" <osalvador@suse.de>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH v2] mm/page_alloc: fix counting of free pages after take off from buddy
Date: Wed, 26 May 2021 08:43:28 +0800	[thread overview]
Message-ID: <1eabe244-4568-e1e1-7f9e-235175cc8c1d@sangfor.com.cn> (raw)
In-Reply-To: <20210525083228.GA3327407@hori.linux.bs1.fc.nec.co.jp>

On 2021/5/25 16:32, HORIGUCHI NAOYA(堀口 直也) wrote:
> On Sat, May 08, 2021 at 11:55:33AM +0800, Ding Hui wrote:
>> Recently we found there is a lot MemFree left in /proc/meminfo after
>> do a lot of pages soft offline.
>>
>> I think it's incorrect since NR_FREE_PAGES should not contain HWPoison pages.
>> For offline free pages, after a successful call take_page_off_buddy(), the
>> page is no longer belong to buddy allocator, and will not be used any more,
>> but we missed accounting NR_FREE_PAGES in this situation.
>>
>> Do update like rmqueue() does.
>>
>> Signed-off-by: Ding Hui <dinghui@sangfor.com.cn>
>> ---
>> V2:
>> use __mod_zone_freepage_state instead of __mod_zone_page_state
>>
>>   mm/page_alloc.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index cfc72873961d..e124a615303b 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -8947,6 +8947,7 @@ bool take_page_off_buddy(struct page *page)
>>   			del_page_from_free_list(page_head, zone, page_order);
>>   			break_down_buddy_pages(zone, page_head, page, 0,
>>   						page_order, migratetype);
>> +			__mod_zone_freepage_state(zone, -1, migratetype);
> 
> Page offline code (see set_migratetype_isolate()) seems to handle
> NR_FREE_PAGES counter in its own way, so I think that it's more correct to
> call __mod_zone_freepage_state() only when is_migrate_isolate(migratetype))
> is false.
> 
> Otherwise, the patch looks good to me.
> 

Thanks for reply and suggestion, I'll send v3 patch later.

>>   			ret = true;
>>   			break;
>>   		}
>> -- 
>> 2.17.1


-- 
Thanks,
- Ding Hui

  reply	other threads:[~2021-05-26  0:43 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-21  2:04 [RFC PATCH] " Ding Hui
2021-04-28 14:54 ` David Hildenbrand
2021-04-30  9:43   ` Ding Hui
2021-05-08  3:55     ` [PATCH v2] " Ding Hui
2021-05-25  8:32       ` HORIGUCHI NAOYA(堀口 直也)
2021-05-26  0:43         ` Ding Hui [this message]
2021-05-06  2:49   ` [RFC PATCH] " HORIGUCHI NAOYA(堀口 直也)
2021-05-06  4:01     ` Ding Hui
2021-05-06  7:30       ` HORIGUCHI NAOYA(堀口 直也)
2021-05-07  1:46         ` Ding Hui

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