• Minchan Kim's avatar
    mm: move lazily freed pages to inactive list · 10853a03
    Minchan Kim authored
    MADV_FREE is a hint that it's okay to discard pages if there is memory
    pressure and we use reclaimers(ie, kswapd and direct reclaim) to free
    them so there is no value keeping them in the active anonymous LRU so
    this patch moves them to inactive LRU list's head.
    
    This means that MADV_FREE-ed pages which were living on the inactive
    list are reclaimed first because they are more likely to be cold rather
    than recently active pages.
    
    An arguable issue for the approach would be whether we should put the
    page to the head or tail of the inactive list.  I chose head because the
    kernel cannot make sure it's really cold or warm for every MADV_FREE
    usecase but at least we know it's not *hot*, so landing of inactive head
    would be a comprimise for various usecases.
    
    This fixes suboptimal behavior of MADV_FREE when pages living on the
    active list will sit there for a long time even under memory pressure
    while the inactive list is reclaimed heavily.  This basically breaks the
    whole purpose of using MADV_FREE to help the system to free memory which
    is might not be used.
    Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
    Acked-by: default avatarHugh Dickins <hughd@google.com>
    Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Shaohua Li <shli@kernel.org>
    Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
    Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
    Cc: <yalin.wang2010@gmail.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Chen Gang <gang.chen.5i5j@gmail.com>
    Cc: Chris Zankel <chris@zankel.net>
    Cc: Daniel Micay <danielmicay@gmail.com>
    Cc: Darrick J. Wong <darrick.wong@oracle.com>
    Cc: David S. Miller <davem@davemloft.net>
    Cc: Helge Deller <deller@gmx.de>
    Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
    Cc: Jason Evans <je@fb.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Cc: Kirill A. Shutemov <kirill@shutemov.name>
    Cc: Matt Turner <mattst88@gmail.com>
    Cc: Max Filippov <jcmvbkbc@gmail.com>
    Cc: Michael Kerrisk <mtk.manpages@gmail.com>
    Cc: Mika Penttil <mika.penttila@nextfour.com>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: Richard Henderson <rth@twiddle.net>
    Cc: Roland Dreier <roland@kernel.org>
    Cc: Russell King <rmk@arm.linux.org.uk>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Wu Fengguang <fengguang.wu@intel.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    10853a03
madvise.c 18.4 KB