Hi Minchan Thanks for reviewing. On 2017/2/2 15:28, Minchan Kim wrote: > On Wed, Feb 01, 2017 at 11:00:23AM +0100, Michal Hocko wrote: >> On Wed 01-02-17 18:46:36, Minchan Kim wrote: >>> On Wed, Feb 01, 2017 at 08:59:24AM +0100, Michal Hocko wrote: >>>> On Wed 01-02-17 15:48:21, Minchan Kim wrote: >>>>> Hi Yisheng, >>>>> >>>>> On Tue, Jan 31, 2017 at 09:06:18PM +0800, ysxie@xxxxxxxxxxx wrote: >>>>>> From: Yisheng Xie <xieyisheng1@xxxxxxxxxx> >>>>>> >>>>>> This patch changes the return type of isolate_movable_page() >>>>>> from bool to int. It will return 0 when isolate movable page >>>>>> successfully, return -EINVAL when the page is not a non-lru movable >>>>>> page, and for other cases it will return -EBUSY. >>>>>> >>>>>> There is no functional change within this patch but prepare >>>>>> for later patch. >>>>>> >>>>>> Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx> >>>>>> Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx> >>>>> >>>>> Sorry for missing this one you guys were discussing. >>>>> I don't understand the patch's goal although I read later patches. >>>> >>>> The point is that the failed isolation has to propagate error up the >>>> call chain to the userspace which has initiated the migration. >>>> >>>>> isolate_movable_pages returns success/fail so that's why I selected >>>>> bool rather than int but it seems you guys want to propagate more >>>>> detailed error to the user so added -EBUSY and -EINVAL. >>>>> >>>>> But the question is why isolate_lru_pages doesn't have -EINVAL? >>>> >>>> It doesn't have to same as isolate_movable_pages. We should just return >>>> EBUSY when the page is no longer movable. >>> >>> Why isolate_lru_page is okay to return -EBUSY in case of race while >>> isolate_movable_page should return -EINVAL? >>> What's the logic in your mind? I totally cannot understand. >> >> Let me rephrase. Both should return EBUSY. > > It means it's binary return value(success: 0 fail : -EBUSY) so IMO, > bool is better and caller should return -EBUSY if that functions > returns *false*. No need to make deeper propagation level. > Anyway, it's trivial so I'm not against it if you want to make > isolate_movable_page returns int. Insetad, please remove -EINVAL > in this patch and just return -EBUSY for isolate_movable_page to > be consistent with isolate_lru_page. > Then, we don't need to fix any driver side, either. Even, no need to > update any document because you don't add any new error value. > Ok, I will remove the -EINVAL. Thanks. Yisheng Xie. > That's enough. > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > > . > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
