Re: [PATCH V2] MCE: fix an error of mce_bad_pages statistics

[Xishi Qiu <qiuxishi@huawei.com>]

On 2012/12/11 11:48, Simon Jeons wrote:

> On Tue, 2012-12-11 at 04:19 +0100, Andi Kleen wrote:
>> On Mon, Dec 10, 2012 at 09:13:11PM -0600, Simon Jeons wrote:
>>> On Tue, 2012-12-11 at 04:01 +0100, Andi Kleen wrote:
>>>>> Oh, it will be putback to lru list during migration. So does your "some
>>>>> time" mean before call check_new_page?
>>>>
>>>> Yes until the next check_new_page() whenever that is. If the migration
>>>> works it will be earlier, otherwise later.
>>>
>>> But I can't figure out any page reclaim path check if the page is set
>>> PG_hwpoison, can poisoned pages be rclaimed?
>>
>> The only way to reclaim a page is to free and reallocate it.
> 
> Then why there doesn't have check in reclaim path to avoid relcaim
> poisoned page?
> 
> 			-Simon

Hi Simon,

If the page is free, it will be set PG_hwpoison, and soft_offline_page() is done.
When the page is alocated later, check_new_page() will find the poisoned page and
isolate the whole buddy block(just drop the block).

If the page is not free, soft_offline_page() try to free it first, if this is
failed, it will migrate the page, but the page is still in LRU list after migration,
migrate_pages()
	unmap_and_move()
		if (rc != -EAGAIN) {
			...
			putback_lru_page(page);
		}
We can use lru_add_drain_all() to drain lru pagevec, at last free_hot_cold_page()
will be called, and free_pages_prepare() check the poisoned pages.
free_pages_prepare()
	free_pages_check()
		bad_page()

Is this right, Andi?

Thanks
Xishi Qiu

>>
>> -Andi
> 
> 
> 
> 



--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>