From: Minchan Kim <minchan@kernel.org>
To: Shaohua Li <shli@fb.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Kernel-team@fb.com, mhocko@suse.com, hughd@google.com,
hannes@cmpxchg.org, riel@redhat.com, mgorman@techsingularity.net,
akpm@linux-foundation.org
Subject: Re: [PATCH V5 4/6] mm: reclaim MADV_FREE pages
Date: Tue, 28 Feb 2017 14:02:16 +0900 [thread overview]
Message-ID: <20170228050216.GB2702@bbox> (raw)
In-Reply-To: <20170227161907.GC62304@shli-mbp.local>
On Mon, Feb 27, 2017 at 08:19:08AM -0800, Shaohua Li wrote:
> On Mon, Feb 27, 2017 at 03:33:15PM +0900, Minchan Kim wrote:
> > Hi Shaohua,
> >
> > On Fri, Feb 24, 2017 at 01:31:47PM -0800, Shaohua Li wrote:
> > > When memory pressure is high, we free MADV_FREE pages. If the pages are
> > > not dirty in pte, the pages could be freed immediately. Otherwise we
> > > can't reclaim them. We put the pages back to anonumous LRU list (by
> > > setting SwapBacked flag) and the pages will be reclaimed in normal
> > > swapout way.
> > >
> > > We use normal page reclaim policy. Since MADV_FREE pages are put into
> > > inactive file list, such pages and inactive file pages are reclaimed
> > > according to their age. This is expected, because we don't want to
> > > reclaim too many MADV_FREE pages before used once pages.
> > >
> > > Based on Minchan's original patch
> > >
> > > Cc: Michal Hocko <mhocko@suse.com>
> > > Cc: Minchan Kim <minchan@kernel.org>
> > > Cc: Hugh Dickins <hughd@google.com>
> > > Cc: Johannes Weiner <hannes@cmpxchg.org>
> > > Cc: Rik van Riel <riel@redhat.com>
> > > Cc: Mel Gorman <mgorman@techsingularity.net>
> > > Cc: Andrew Morton <akpm@linux-foundation.org>
> > > Signed-off-by: Shaohua Li <shli@fb.com>
> > > ---
> > > include/linux/rmap.h | 2 +-
> > > mm/huge_memory.c | 2 ++
> > > mm/madvise.c | 1 +
> > > mm/rmap.c | 40 +++++++++++++++++-----------------------
> > > mm/vmscan.c | 34 ++++++++++++++++++++++------------
> > > 5 files changed, 43 insertions(+), 36 deletions(-)
> > >
> > > diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> > > index 7a39414..fee10d7 100644
> > > --- a/include/linux/rmap.h
> > > +++ b/include/linux/rmap.h
> > > @@ -298,6 +298,6 @@ static inline int page_mkclean(struct page *page)
> > > #define SWAP_AGAIN 1
> > > #define SWAP_FAIL 2
> > > #define SWAP_MLOCK 3
> > > -#define SWAP_LZFREE 4
> > > +#define SWAP_DIRTY 4
> >
> > I still don't convinced why we should introduce SWAP_DIRTY in try_to_unmap.
> > https://marc.info/?l=linux-mm&m=148797879123238&w=2
> >
> > We have been SetPageMlocked in there but why cannot we SetPageSwapBacked
> > in there? It's not a thing to change LRU type but it's just indication
> > we found the page's status changed in late.
>
> This one I don't have strong preference. Personally I agree with Johannes,
> handling failure in vmscan sounds better. But since the failure handling is
> just one statement, this probably doesn't make too much difference. If Johannes
> and you made an agreement, I'll follow.
I don't want to add unnecessary new return value(i.e., SWAP_DIRTY).
If VM found lazyfree page dirty in try_to_unmap_one, it means "non-swappable page"
so it's natural to set SetPageSwapBacked in there and return just SWAP_FAIL to
activate it in vmscan.c. SWAP_FAIL means the page is non-swappable so it should be
activated. I don't see any problem in there like software engineering pov.
However, it seems everyone are happy with introdcuing SWAP_DIRTY so I don't
insist on it which is not critical for this patchset.
I looked over try_to_unmap and callers. Now, I think we could remove SWAP_MLOCK
and maybe SWAP_AGAIN as well as SWAP_DIRTY that is to make try_to_unmap *bool*.
So, it could be done by separate patchset. I will look into that in more.
Acked-by: Minchan Kim <minchan@kernel.org>
Thanks.
next prev parent reply other threads:[~2017-02-28 5:48 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-24 21:31 [PATCH V5 0/6] mm: fix some MADV_FREE issues Shaohua Li
2017-02-24 21:31 ` [PATCH V5 1/6] mm: delete unnecessary TTU_* flags Shaohua Li
2017-02-27 13:48 ` Michal Hocko
2017-02-24 21:31 ` [PATCH V5 2/6] mm: don't assume anonymous pages have SwapBacked flag Shaohua Li
2017-02-27 6:48 ` Hillf Danton
2017-02-27 14:35 ` Michal Hocko
2017-02-27 16:10 ` Shaohua Li
2017-02-27 16:28 ` Michal Hocko
2017-02-24 21:31 ` [PATCH V5 3/6] mm: move MADV_FREE pages into LRU_INACTIVE_FILE list Shaohua Li
2017-02-27 6:28 ` Minchan Kim
2017-02-27 16:13 ` Shaohua Li
2017-02-27 16:30 ` Michal Hocko
2017-02-28 2:53 ` Minchan Kim
2017-02-27 14:53 ` Michal Hocko
2017-02-27 17:15 ` Johannes Weiner
2017-02-28 3:19 ` Hillf Danton
2017-02-24 21:31 ` [PATCH V5 4/6] mm: reclaim MADV_FREE pages Shaohua Li
2017-02-27 6:33 ` Minchan Kim
2017-02-27 16:19 ` Shaohua Li
2017-02-27 16:32 ` Michal Hocko
2017-02-28 5:02 ` Minchan Kim [this message]
2017-02-27 15:05 ` Michal Hocko
2017-02-27 17:21 ` Johannes Weiner
2017-02-28 3:21 ` Hillf Danton
2017-02-24 21:31 ` [PATCH V5 5/6] mm: enable MADV_FREE for swapless system Shaohua Li
2017-02-27 15:06 ` Michal Hocko
2017-02-28 3:22 ` Hillf Danton
2017-02-28 5:02 ` Minchan Kim
2017-02-24 21:31 ` [PATCH V5 6/6] proc: show MADV_FREE pages info in smaps Shaohua Li
2017-02-27 15:06 ` Michal Hocko
2017-02-28 3:23 ` Hillf Danton
2017-03-01 13:36 ` Michal Hocko
2017-03-01 17:37 ` Shaohua Li
2017-03-01 17:49 ` Michal Hocko
2017-03-01 18:18 ` Shaohua Li
2017-03-01 18:31 ` Johannes Weiner
2017-03-01 18:57 ` Michal Hocko
2017-03-02 7:39 ` Minchan Kim
2017-03-02 14:01 ` Johannes Weiner
2017-03-02 16:30 ` Michal Hocko
2017-03-04 0:10 ` Andrew Morton
2017-03-07 10:05 ` Michal Hocko
2017-03-07 22:43 ` Andrew Morton
2017-03-08 5:36 ` Minchan Kim
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