Re: [mm-unstable PATCH v4 5/9] mm, hwpoison: make unpoison aware of raw error info in hwpoisoned hugepage

[Miaohe Lin <linmiaohe@huawei.com>]

On 2022/7/7 9:35, HORIGUCHI NAOYA(堀口 直也) wrote:
> On Wed, Jul 06, 2022 at 11:06:28PM +0000, HORIGUCHI NAOYA(堀口 直也) wrote:
>> On Wed, Jul 06, 2022 at 10:58:53AM +0800, Miaohe Lin wrote:
>>> On 2022/7/4 9:33, Naoya Horiguchi wrote:
>>>> From: Naoya Horiguchi <naoya.horiguchi@nec.com>
>>>>
>>>> Raw error info list needs to be removed when hwpoisoned hugetlb is
>>>> unpoisoned.  And unpoison handler needs to know how many errors there
>>>> are in the target hugepage. So add them.
>>>>
>>>> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
>>>> ---
>>>> @@ -2287,6 +2301,7 @@ int unpoison_memory(unsigned long pfn)
>>>
>>> Is it safe to unpoison hugepage when HPageRawHwpUnreliable? I'm afraid because
>>> some raw error info is missing..
>>
>> Ah, right. We need prevent it.  I'll fix it by inserting the check.
>>
>>  static inline long free_raw_hwp_pages(struct page *hpage, bool move_flag)
>>  {
>>          struct llist_head *head;
>>          struct llist_node *t, *tnode;
>>          long count = 0;
>>  
>> +        if (!HPageRawHwpUnreliable(hpage))
>> +                return 0;

IIUC, even if we return 0 here, the caller will still do TestClearPageHWPoison(please see below
code diff) and succeeds to unpoison the page. Or am I miss something?

@@ -2334,6 +2349,8 @@ int unpoison_memory(unsigned long pfn)

 	ret = get_hwpoison_page(p, MF_UNPOISON);
 	if (!ret) {
+		if (PageHuge(p))
+			count = free_raw_hwp_pages(page, false);
 		ret = TestClearPageHWPoison(page) ? 0 : -EBUSY;
 	} else if (ret < 0) {
 		if (ret == -EHWPOISON) {

> 
> No, I meant "if (HPageRawHwpUnreliable(hpage))", sorry for the noise :(

No, thanks for your hard work!

> 
> - Naoya Horiguchi

Thanks.

>