lkml.org 
[lkml]   [2011]   [Jan]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[BUGFIX][PATCH v4] memcg: fix memory migration of shmem swapcache
    > Sorry for nit-picking but succeed is not as good as succeeded,
    > successful, successful_migration or migration_ok
    >
    OK, I use "migration_ok".

    ===
    From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>

    In current implimentation, mem_cgroup_end_migration() decides whether the page
    migration has succeeded or not by checking "oldpage->mapping".

    But if we are tring to migrate a shmem swapcache, the page->mapping of it is
    NULL from the begining, so the check would be invalid.
    As a result, mem_cgroup_end_migration() assumes the migration has succeeded
    even if it's not, so "newpage" would be freed while it's not uncharged.

    This patch fixes it by passing mem_cgroup_end_migration() the result of the
    page migration.

    Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
    Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
    Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    ---
    v3->v4
    - s/succeed/migration_ok
    v2->v3
    - s/success/succeed
    v1->v2
    - pass mem_cgroup_end_migration() "bool" instead of "int".

    include/linux/memcontrol.h | 5 ++---
    mm/memcontrol.c | 5 ++---
    mm/migrate.c | 2 +-
    3 files changed, 5 insertions(+), 7 deletions(-)

    diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
    index 159a076..769c318 100644
    --- a/include/linux/memcontrol.h
    +++ b/include/linux/memcontrol.h
    @@ -93,7 +93,7 @@ extern int
    mem_cgroup_prepare_migration(struct page *page,
    struct page *newpage, struct mem_cgroup **ptr);
    extern void mem_cgroup_end_migration(struct mem_cgroup *mem,
    - struct page *oldpage, struct page *newpage);
    + struct page *oldpage, struct page *newpage, bool migration_ok);

    /*
    * For memory reclaim.
    @@ -231,8 +231,7 @@ mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
    }

    static inline void mem_cgroup_end_migration(struct mem_cgroup *mem,
    - struct page *oldpage,
    - struct page *newpage)
    + struct page *oldpage, struct page *newpage, bool migration_ok)
    {
    }

    diff --git a/mm/memcontrol.c b/mm/memcontrol.c
    index 61678be..c35f817 100644
    --- a/mm/memcontrol.c
    +++ b/mm/memcontrol.c
    @@ -2856,7 +2856,7 @@ int mem_cgroup_prepare_migration(struct page *page,

    /* remove redundant charge if migration failed*/
    void mem_cgroup_end_migration(struct mem_cgroup *mem,
    - struct page *oldpage, struct page *newpage)
    + struct page *oldpage, struct page *newpage, bool migration_ok)
    {
    struct page *used, *unused;
    struct page_cgroup *pc;
    @@ -2865,8 +2865,7 @@ void mem_cgroup_end_migration(struct mem_cgroup *mem,
    return;
    /* blocks rmdir() */
    cgroup_exclude_rmdir(&mem->css);
    - /* at migration success, oldpage->mapping is NULL. */
    - if (oldpage->mapping) {
    + if (!migration_ok) {
    used = oldpage;
    unused = newpage;
    } else {
    diff --git a/mm/migrate.c b/mm/migrate.c
    index 6ae8a66..be66b23 100644
    --- a/mm/migrate.c
    +++ b/mm/migrate.c
    @@ -756,7 +756,7 @@ rcu_unlock:
    rcu_read_unlock();
    uncharge:
    if (!charge)
    - mem_cgroup_end_migration(mem, page, newpage);
    + mem_cgroup_end_migration(mem, page, newpage, rc == 0);
    unlock:
    unlock_page(page);

    --
    1.7.1


    \
     
     \ /
      Last update: 2011-01-06 07:41    [W:0.026 / U:59.724 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site