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    Subject[PATCH 1/6] memcg: move charge swapin under lock
    While page-cache's charge/uncharge is done under page_lock(), swap-cache
    isn't. (anonymous page is charged when it's newly allocated.)

    This patch moves do_swap_page()'s charge() call under lock.
    I don't see any bad problem *now* but this fix will be good for future
    for avoiding unneccesary racy state.


    Changelog: (v6) -> (v7)
    - no changes.
    Changelog: (v5) -> (v6)
    - mark_page_accessed() is moved before lock_page().
    - fixed missing unlock_page()
    (no changes in previous version)

    Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
    Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>


    mm/memory.c | 11 ++++++-----
    1 file changed, 6 insertions(+), 5 deletions(-)

    Index: mmotm-2.6.27-rc7+/mm/memory.c
    ===================================================================
    --- mmotm-2.6.27-rc7+.orig/mm/memory.c
    +++ mmotm-2.6.27-rc7+/mm/memory.c
    @@ -2326,16 +2326,17 @@ static int do_swap_page(struct mm_struct
    count_vm_event(PGMAJFAULT);
    }

    + mark_page_accessed(page);
    +
    + lock_page(page);
    + delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
    +
    if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
    - delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
    ret = VM_FAULT_OOM;
    + unlock_page(page);
    goto out;
    }

    - mark_page_accessed(page);
    - lock_page(page);
    - delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
    -
    /*
    * Back out if somebody else already faulted in this pte.
    */


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