On Sat, 28 Jul 2012, JoonSoo Kim wrote:

2012/7/28 Christoph Lameter [off-list ref]:

quoted

On Sat, 28 Jul 2012, Joonsoo Kim wrote:

quoted

move_pages() syscall may return success in case that
do_move_page_to_node_array return positive value which means migration failed.

Nope. It only means that the migration for some pages has failed. This may
still be considered successful for the app if it moves 10000 pages and one
failed.

This patch would break the move_pages() syscall because an error code
return from do_move_pages_to_node_array() will cause the status byte for
each page move to not be updated anymore. Application will not be able to
tell anymore which pages were successfully moved and which are not.

In case of returning non-zero, valid status is not required according
to man page.

Cannot find a statement like that in the man page. The return code
description is incorrect. It should that that is returns the number of
pages not moved otherwise an error code (Michael please fix the manpage).

So, this patch would not break the move_pages() syscall.

It changes the way the system call is behaving right now.

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