• KAMEZAWA Hiroyuki's avatar
    hibernation: freeze swap at hibernation · d2997b10
    KAMEZAWA Hiroyuki authored
    When taking a memory snapshot in hibernate_snapshot(), all (directly
    called) memory allocations use GFP_ATOMIC.  Hence swap misusage during
    hibernation never occurs.
    
    But from a pessimistic point of view, there is no guarantee that no page
    allcation has __GFP_WAIT.  It is better to have a global indication "we
    enter hibernation, don't use swap!".
    
    This patch tries to freeze new-swap-allocation during hibernation.  (All
    user processes are frozenm so swapin is not a concern).
    
    This way, no updates will happen to swap_map[] between
    hibernate_snapshot() and save_image().  Swap is thawed when swsusp_free()
    is called.  We can be assured that swap corruption will not occur.
    Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Cc: Ondrej Zary <linux@rainbow-software.org>
    Cc: Balbir Singh <balbir@in.ibm.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    d2997b10
swap.c 15.5 KB