linux-kernel - Re: [PATCH v4 2/2] HWPOISON: soft offlining for non-lru movable page

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Date:   Mon, 30 Jan 2017 17:38:47 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Yisheng Xie <ysxie@...mail.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        n-horiguchi@...jp.nec.com, akpm@...ux-foundation.org,
        minchan@...nel.org, vbabka@...e.cz, guohanjun@...wei.com,
        qiuxishi@...wei.com
Subject: Re: [PATCH v4 2/2] HWPOISON: soft offlining for non-lru movable page

On Mon 30-01-17 23:04:13, Yisheng Xie wrote:
> Hi, Michal,
> Sorry for late reply.
> 
> On 01/26/2017 05:27 PM, Michal Hocko wrote:
> > On Wed 25-01-17 23:05:38, ysxie@...mail.com wrote:
> >> From: Yisheng Xie <xieyisheng1@...wei.com>
> >>
> >> This patch is to extends soft offlining framework to support
> >> non-lru page, which already support migration after
> >> commit bda807d44454 ("mm: migrate: support non-lru movable page
> >> migration")
> >>
> >> When memory corrected errors occur on a non-lru movable page,
> >> we can choose to stop using it by migrating data onto another
> >> page and disable the original (maybe half-broken) one.
> >>
> >> Signed-off-by: Yisheng Xie <xieyisheng1@...wei.com>
> >> Suggested-by: Michal Hocko <mhocko@...nel.org>
> >> Suggested-by: Minchan Kim <minchan@...nel.org>
> >> Reviewed-by: Minchan Kim <minchan@...nel.org>
> >> Acked-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> >> CC: Vlastimil Babka <vbabka@...e.cz>
> >> ---
> >>  mm/memory-failure.c | 26 ++++++++++++++++----------
> >>  1 file changed, 16 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> >> index f283c7e..56e39f8 100644
> >> --- a/mm/memory-failure.c
> >> +++ b/mm/memory-failure.c
> >> @@ -1527,7 +1527,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags)
> >>  {
> >>  	int ret = __get_any_page(page, pfn, flags);
> >>  
> >> -	if (ret == 1 && !PageHuge(page) && !PageLRU(page)) {
> >> +	if (ret == 1 && !PageHuge(page) &&
> >> +	    !PageLRU(page) && !__PageMovable(page)) {
> >>  		/*
> >>  		 * Try to free it.
> >>  		 */
> > Is this sufficient? Not that I am familiar with get_any_page() but
> > __get_any_page doesn't seem to be aware of movable pages and neither
> > shake_page is.
> Sorry,maybe I do not quite get what you mean.
>  If the page can be migrated, it can skip "shake_page and __get_any_page once more" here,
> though it is not a free page. right ?
> Please let me know if I miss anything.

No, you are right, it is me who read the code incorrectly. Sorry about
the confusion.
-- 
Michal Hocko
SUSE Labs