Re: [PATCH 7/8] vrange: Add method to purge volatile ranges

[Minchan Kim]

On Tue, Jun 11, 2013 at 09:22:50PM -0700, John Stultz wrote:
> From: Minchan Kim <minchan@xxxxxxxxxx>
> 
> This patch adds discarding function to purge volatile ranges under
> memory pressure. Logic is as following:
> 
> 1. Memory pressure happens
> 2. VM start to reclaim pages
> 3. Check the page is in volatile range.
> 4. If so, zap the page from the process's page table.
>    (By semantic vrange(2), we should mark it with another one to
>     make page fault when you try to access the address. It will
>     be introduced later patch)
> 5. If page is unmapped from all processes, discard it instead of swapping.
> 
> This patch does not address the case where there is no swap, which
> keeps anonymous pages from being aged off the LRUs. Minchan has
> additional patches that add support for purging anonymous pages
> 
> XXX: First pass at file purging. Seems to work, but is likely broken
> and needs close review.
> 
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Android Kernel Team <kernel-team@xxxxxxxxxxx>
> Cc: Robert Love <rlove@xxxxxxxxxx>
> Cc: Mel Gorman <mel@xxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Dmitry Adamushko <dmitry.adamushko@xxxxxxxxx>
> Cc: Dave Chinner <david@xxxxxxxxxxxxx>
> Cc: Neil Brown <neilb@xxxxxxx>
> Cc: Andrea Righi <andrea@xxxxxxxxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> Cc: Mike Hommey <mh@xxxxxxxxxxxx>
> Cc: Taras Glek <tglek@xxxxxxxxxxx>
> Cc: Dhaval Giani <dgiani@xxxxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx>
> Cc: Michel Lespinasse <walken@xxxxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx <linux-mm@xxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> [jstultz: Reworked to add purging of file pages, commit log tweaks]
> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
> ---
>  include/linux/rmap.h   |  12 +-
>  include/linux/swap.h   |   1 +
>  include/linux/vrange.h |   7 ++
>  mm/ksm.c               |   2 +-
>  mm/rmap.c              |  30 +++--
>  mm/swapfile.c          |  36 ++++++
>  mm/vmscan.c            |  16 ++-
>  mm/vrange.c            | 332 +++++++++++++++++++++++++++++++++++++++++++++++++
>  8 files changed, 420 insertions(+), 16 deletions(-)

This patch has some bugs so below patch should fix them and pass my
simple cases.