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    SubjectRe: [RFC PATCH 0/3] Obey mark_page_accessed hint given by filesystems
    Hi Mel,
    On 04/30/2013 12:31 AM, Mel Gorman wrote:
    > Andrew Perepechko reported a problem whereby pages are being prematurely
    > evicted as the mark_page_accessed() hint is ignored for pages that are
    > currently on a pagevec -- http://www.spinics.net/lists/linux-ext4/msg37340.html .
    > Alexey Lyahkov and Robin Dong have also reported problems recently that
    > could be due to hot pages reaching the end of the inactive list too quickly
    > and be reclaimed.

    Both shrink_active_list and shrink_inactive_list can call
    lru_add_drain(), why the hot pages can't be mark Actived during this time?

    > Rather than addressing this on a per-filesystem basis, this series aims
    > to fix the mark_page_accessed() interface by deferring what LRU a page
    > is added to pagevec drain time and allowing mark_page_accessed() to call
    > SetPageActive on a pagevec page. This opens some important races that
    > I think should be harmless but needs double checking. The races and the
    > VM_BUG_ON checks that are removed are all described in patch 2.
    >
    > This series received only very light testing but it did not immediately
    > blow up and a debugging patch confirmed that pages are now getting added
    > to the active file LRU list that would previously have been added to the
    > inactive list.
    >
    > fs/cachefiles/rdwr.c | 30 ++++++------------------
    > fs/nfs/dir.c | 7 ++----
    > include/linux/pagevec.h | 34 +--------------------------
    > mm/swap.c | 61 ++++++++++++++++++++++++-------------------------
    > mm/vmscan.c | 3 ---
    > 5 files changed, 40 insertions(+), 95 deletions(-)
    >



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