Date: Tue, 14 Mar 2017 16:34:16 +0900
From: Minchan Kim <minchan@kernel.org>
To: Hillf Danton <hillf.zj@alibaba-inc.com>
CC: "'Andrew Morton'" <akpm@linux-foundation.org>,
        <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        <kernel-team@lge.com>, "'Johannes Weiner'" <hannes@cmpxchg.org>,
        "'Michal Hocko'" <mhocko@suse.com>,
        "'Kirill A. Shutemov'" <kirill.shutemov@linux.intel.com>,
        "'Anshuman Khandual'" <khandual@linux.vnet.ibm.com>
Subject: Re: [PATCH v1 02/10] mm: remove SWAP_DIRTY in ttu
Message-ID: <20170314073416.GA29720@bbox>
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 <099201d29bc3$e3ab2d60$ab018820$@alibaba-inc.com>
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Hello Hillf,

On Mon, Mar 13, 2017 at 02:34:37PM +0800, Hillf Danton wrote:
> 
> On March 13, 2017 8:36 AM Minchan Kim wrote: 
> > 
> > If we found lazyfree page is dirty, try_to_unmap_one can just
> > SetPageSwapBakced in there like PG_mlocked page and just return
> > with SWAP_FAIL which is very natural because the page is not
> > swappable right now so that vmscan can activate it.
> > There is no point to introduce new return value SWAP_DIRTY
> > in ttu at the moment.
> > 
> > Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > Signed-off-by: Minchan Kim <minchan@kernel.org>
> > ---
> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
> 
> >  include/linux/rmap.h | 1 -
> >  mm/rmap.c            | 6 +++---
> >  mm/vmscan.c          | 3 ---
> >  3 files changed, 3 insertions(+), 7 deletions(-)
> > 
> > diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> > index fee10d7..b556eef 100644
> > --- a/include/linux/rmap.h
> > +++ b/include/linux/rmap.h
> > @@ -298,6 +298,5 @@ static inline int page_mkclean(struct page *page)
> >  #define SWAP_AGAIN	1
> >  #define SWAP_FAIL	2
> >  #define SWAP_MLOCK	3
> > -#define SWAP_DIRTY	4
> > 
> >  #endif	/* _LINUX_RMAP_H */
> > diff --git a/mm/rmap.c b/mm/rmap.c
> > index 9dbfa6f..d47af09 100644
> > --- a/mm/rmap.c
> > +++ b/mm/rmap.c
> > @@ -1414,7 +1414,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> >  			 */
> >  			if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
> >  				WARN_ON_ONCE(1);
> > -				ret = SWAP_FAIL;
> > +				ret = false;
> Nit:
> Hm looks like stray merge.
> Not sure it's really needed. 

rebase fail ;-O

Thanks!