Re: + mm-move_pages-fix-the-return-value-if-there-are-not-migrated-pages.patch added to -mm tree

[Wei Yang <richardw.yang@linux.intel.com>]

On Sat, Jan 18, 2020 at 02:47:54PM -0800, akpm@linux-foundation.org wrote:
>
>The patch titled
>     Subject: mm/migrate.c: move_pages: fix the return value if there are not-migrated pages
>has been added to the -mm tree.  Its filename is
>     mm-move_pages-fix-the-return-value-if-there-are-not-migrated-pages.patch
>
>This patch should soon appear at
>    http://ozlabs.org/~akpm/mmots/broken-out/mm-move_pages-fix-the-return-value-if-there-are-not-migrated-pages.patch
>and later at
>    http://ozlabs.org/~akpm/mmotm/broken-out/mm-move_pages-fix-the-return-value-if-there-are-not-migrated-pages.patch
>
>Before you just go and hit "reply", please:
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>   b) Prefer to cc a suitable mailing list as well
>   c) Ideally: find the original patch on the mailing list and do a
>      reply-to-all to that, adding suitable additional cc's
>
>*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
>
>The -mm tree is included into linux-next and is updated
>there every 3-4 working days

Hi Andrew

I am afraid this patch doesn't fully fix the problem. Please wait a minute.

>
>------------------------------------------------------
>From: Yang Shi <yang.shi@linux.alibaba.com>
>Subject: mm/migrate.c: move_pages: fix the return value if there are not-migrated pages
>
>do_move_pages_to_node() might return > 0 value, the number of pages that
>are not migrated, then the value will be returned to userspace directly. 
>But, move_pages() syscall would just return 0 or errno.  So, we need reset
>the return value to 0 for such case as pre-v4.17 did.
>
>Link: http://lkml.kernel.org/r/1579325203-16405-1-git-send-email-yang.shi@linux.alibaba.com
>Fixes: a49bd4d71637 ("mm, numa: rework do_pages_move")
>Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
>Cc: Michal Hocko <mhocko@suse.com>
>Cc: Wei Yang <richardw.yang@linux.intel.com>
>Cc: <stable@vger.kernel.org>    [4.17+]
>Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>---
>
> mm/migrate.c |    5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
>--- a/mm/migrate.c~mm-move_pages-fix-the-return-value-if-there-are-not-migrated-pages
>+++ a/mm/migrate.c
>@@ -1659,8 +1659,11 @@ static int do_pages_move(struct mm_struc
> 			goto out_flush;
> 
> 		err = do_move_pages_to_node(mm, &pagelist, current_node);
>-		if (err)
>+		if (err) {
>+			if (err > 0)
>+				err = 0;
> 			goto out;
>+		}
> 		if (i > start) {
> 			err = store_status(status, start, current_node, i - start);
> 			if (err)
>_
>
>Patches currently in -mm which might be from yang.shi@linux.alibaba.com are
>
>mm-move_pages-fix-the-return-value-if-there-are-not-migrated-pages.patch

-- 
Wei Yang
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