On 2022/8/4 09:19, Miaohe Lin wrote:
> On 2022/8/3 21:01, Matthew Wilcox wrote:
>> On Wed, Aug 03, 2022 at 10:52:43AM +0800, Yin Fengwei wrote:
>>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>>> index da39ec8afca8..08e21973b120 100644
>>> --- a/mm/memory-failure.c
>>> +++ b/mm/memory-failure.c
>>> @@ -1484,7 +1484,16 @@ static int identify_page_state(unsigned long pfn, struct page *p,
>>>
>>> static int try_to_split_thp_page(struct page *page, const char *msg)
>>> {
>>> + struct page *head = compound_head(page);
>> > +
>>> lock_page(page);
>>> + /*
>>> + * If thp page has private data attached, thp split will fail.
>>> + * Release private data before split thp.
>>> + */
>>> + if (page_has_private(head))
>>> + try_to_release_page(head, GFP_KERNEL);
>>> +
>>> if (unlikely(split_huge_page(page))) {
>>> unsigned long pfn = page_to_pfn(page);
>>
>> It seems a shame to use the old page approach instead of the
>> shiny new folio approach. We're quite close to being able to remove
>> try_to_release_page() in 6.1 or 6.2 so adding a new caller is a bad idea.
>> How about this:
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index da39ec8afca8..765b383288b1 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1484,16 +1484,21 @@ static int identify_page_state(unsigned long pfn, struct page *p,
>>
>> static int try_to_split_thp_page(struct page *page, const char *msg)
>> {
>> - lock_page(page);
>> + struct folio *folio = page_folio(page);
>> +
>> + folio_lock(folio);
>> + if (folio_test_private(folio))
>> + filemap_release_folio(folio, GFP_KERNEL);
>
> If filemap_release_folio fails, we could avoid trying split_huge_page here?
Maybe we could stick to this regarding this is error recovery path
instead of hot path?
>
>> if (unlikely(split_huge_page(page))) {
>> unsigned long pfn = page_to_pfn(page);
>>
>> - unlock_page(page);
>> + folio_unlock(folio);
>> pr_info("%s: %#lx: thp split failed\n", msg, pfn);
>> - put_page(page);
>> + folio_put(folio);
>> return -EBUSY;
>> }
>> - unlock_page(page);
>> + folio = page_folio(page);
>
> Above line (re-fetching folio) might need a comment to avoid future confusing ?
I will add one line comment about why page_folio need here.
>
> Anyway, this patch looks good to me. Thanks for fixing.
Thanks.
Regards
Yin, Fengwei
>
>> + folio_unlock(folio);
>>
>> return 0;
>> }
>>
>> .
>>
>
