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    SubjectRe: [PATCH] tmpfs: Insert tmpfs cache pages to inactive list at first
    On Wed, May 19, 2010 at 05:44:49PM +0900, KOSAKI Motohiro wrote:
    > Shaohua Li reported parallel file copy on tmpfs can lead to
    > OOM killer. This is regression of caused by commit 9ff473b9a7
    > (vmscan: evict streaming IO first). Wow, It is 2 years old patch!
    >
    > Currently, tmpfs file cache is inserted active list at first. It
    > mean the insertion doesn't only increase numbers of pages in anon LRU,
    > but also reduce anon scanning ratio. Therefore, vmscan will get totally
    > confusion. It scan almost only file LRU even though the system have
    > plenty unused tmpfs pages.
    >
    > Historically, lru_cache_add_active_anon() was used by two reasons.
    > 1) Intend to priotize shmem page rather than regular file cache.
    > 2) Intend to avoid reclaim priority inversion of used once pages.
    >
    > But we've lost both motivation because (1) Now we have separate
    > anon and file LRU list. then, to insert active list doesn't help
    > such priotize. (2) In past, one pte access bit will cause page
    > activation. then to insert inactive list with pte access bit mean
    > higher priority than to insert active list. Its priority inversion
    > may lead to uninteded lru chun. but it was already solved by commit
    > 645747462 (vmscan: detect mapped file pages used only once).
    > (Thanks Hannes, you are great!)
    >
    > Thus, now we can use lru_cache_add_anon() instead.
    >
    > Reported-by: Shaohua Li <shaohua.li@intel.com>
    > Cc: Wu Fengguang <fengguang.wu@intel.com>
    > Cc: Johannes Weiner <hannes@cmpxchg.org>

    Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>

    > Cc: Rik van Riel <riel@redhat.com>
    > Cc: Minchan Kim <minchan.kim@gmail.com>
    > Cc: Hugh Dickins <hughd@google.com>
    > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    > ---
    > mm/filemap.c | 2 +-
    > 1 files changed, 1 insertions(+), 1 deletions(-)
    >
    > diff --git a/mm/filemap.c b/mm/filemap.c
    > index b941996..023ef61 100644
    > --- a/mm/filemap.c
    > +++ b/mm/filemap.c
    > @@ -452,7 +452,7 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
    > if (page_is_file_cache(page))
    > lru_cache_add_file(page);
    > else
    > - lru_cache_add_active_anon(page);
    > + lru_cache_add_anon(page);

    Looks like the active_anon and active_file versions have no users
    anymore..


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