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    Subject[-mm][PATCH 3/4] cgroup mm owner callback changes to add task info (v5)

    This patch adds an additional field to the mm_owner callbacks. This field
    is required to get to the mm that changed. Hold mmap_sem in write mode
    before calling the mm_owner_changed callback

    Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
    ---

    include/linux/cgroup.h | 3 ++-
    kernel/cgroup.c | 4 +++-
    kernel/exit.c | 3 +++
    3 files changed, 8 insertions(+), 2 deletions(-)

    diff -puN include/linux/cgroup.h~cgroup-add-task-to-mm-owner-callbacks include/linux/cgroup.h
    --- linux-2.6.26-rc2/include/linux/cgroup.h~cgroup-add-task-to-mm-owner-callbacks 2008-05-21 20:56:54.000000000 +0530
    +++ linux-2.6.26-rc2-balbir/include/linux/cgroup.h 2008-05-21 20:56:54.000000000 +0530
    @@ -310,7 +310,8 @@ struct cgroup_subsys {
    */
    void (*mm_owner_changed)(struct cgroup_subsys *ss,
    struct cgroup *old,
    - struct cgroup *new);
    + struct cgroup *new,
    + struct task_struct *p);
    int subsys_id;
    int active;
    int disabled;
    diff -puN kernel/cgroup.c~cgroup-add-task-to-mm-owner-callbacks kernel/cgroup.c
    --- linux-2.6.26-rc2/kernel/cgroup.c~cgroup-add-task-to-mm-owner-callbacks 2008-05-21 20:56:54.000000000 +0530
    +++ linux-2.6.26-rc2-balbir/kernel/cgroup.c 2008-05-21 20:56:54.000000000 +0530
    @@ -2758,6 +2758,8 @@ void cgroup_fork_callbacks(struct task_s
    * Called on every change to mm->owner. mm_init_owner() does not
    * invoke this routine, since it assigns the mm->owner the first time
    * and does not change it.
    + *
    + * The callbacks are invoked with mmap_sem held in read mode.
    */
    void cgroup_mm_owner_callbacks(struct task_struct *old, struct task_struct *new)
    {
    @@ -2772,7 +2774,7 @@ void cgroup_mm_owner_callbacks(struct ta
    if (oldcgrp == newcgrp)
    continue;
    if (ss->mm_owner_changed)
    - ss->mm_owner_changed(ss, oldcgrp, newcgrp);
    + ss->mm_owner_changed(ss, oldcgrp, newcgrp, new);
    }
    }
    }
    diff -puN kernel/exit.c~cgroup-add-task-to-mm-owner-callbacks kernel/exit.c
    --- linux-2.6.26-rc2/kernel/exit.c~cgroup-add-task-to-mm-owner-callbacks 2008-05-21 20:56:54.000000000 +0530
    +++ linux-2.6.26-rc2-balbir/kernel/exit.c 2008-05-21 20:56:54.000000000 +0530
    @@ -621,6 +621,7 @@ retry:
    assign_new_owner:
    BUG_ON(c == p);
    get_task_struct(c);
    + down_write(&mm->mmap_sem);
    /*
    * The task_lock protects c->mm from changing.
    * We always want mm->owner->mm == mm
    @@ -634,12 +635,14 @@ assign_new_owner:
    if (c->mm != mm) {
    task_unlock(c);
    put_task_struct(c);
    + up_write(&mm->mmap_sem);
    goto retry;
    }
    cgroup_mm_owner_callbacks(mm->owner, c);
    mm->owner = c;
    task_unlock(c);
    put_task_struct(c);
    + up_write(&mm->mmap_sem);
    }
    #endif /* CONFIG_MM_OWNER */

    _
    --
    Warm Regards,
    Balbir Singh
    Linux Technology Center
    IBM, ISTL


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