On 9/7/22 16:34, Andrew Morton wrote:
On Tue, 6 Sep 2022 10:44:01 +0800 Chen Wandun <chenwandun@xxxxxxxxxx> wrote:
It is no need to walk page table and find pages if faultin_page success
and __get_user_pages does't care pages at all, so directly handle next
page.
...
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1198,7 +1198,10 @@ static long __get_user_pages(struct mm_struct *mm,
PTR_ERR(page) == -EMLINK, locked);
switch (ret) {
case 0:
- goto retry;
+ if (pages)
+ goto retry;
+ else
+ goto next_page;
Wow, good point. And it's been doing that for a *long* time!
case -EBUSY:
case -EAGAIN:
ret = 0;
Looks right to me. I redid the changelog somewhat:
: There is no need to walk page tables and find pages if faultin_page)_
: succeeds and __get_user_pages)_ doesn't care about populating the pages[]
: array. So directly go on to handle the next page.
With that re-worded commit description, please feel to add
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
thanks,
--
John Hubbard
NVIDIA
