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SubjectRe: [PATCH 5/5] mm/vmscan: fix misleading comment in isolate_lru_pages()
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On 2021/7/12 15:28, Michal Hocko wrote:
> On Sat 10-07-21 18:03:29, Miaohe Lin wrote:
>> We couldn't know whether the page is being freed elsewhere until we failed
>> to increase the page count.
>
> This is moving a hard to understand comment from one place to another.

If get_page_unless_zero failed, the page could have been freed elsewhere. I think
this looks straightforward but doesn't help a lot. Are you preferring to just
remove this comment ?

Thank you.

> If anything this would benefit from what that elsewhere might be
> typically or simply drop the comment altogether.
>
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>> ---
>> mm/vmscan.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index a74760c48bd8..6e26b3c93242 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1891,7 +1891,6 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
>> */
>> scan += nr_pages;
>> if (!__isolate_lru_page_prepare(page, mode)) {
>> - /* It is being freed elsewhere */
>> list_move(&page->lru, src);
>> continue;
>> }
>> @@ -1901,6 +1900,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
>> * page release code relies on it.
>> */
>> if (unlikely(!get_page_unless_zero(page))) {
>> + /* It is being freed elsewhere. */
>> list_move(&page->lru, src);
>> continue;
>> }
>> --
>> 2.23.0
>

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