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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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