There are some places that are known to operate on tasks'
global pids only:

* the rest_init() call (called on boot)
* the kgdb's getthread
* the create_kthread() (since the kthread is run in init ns)

So use the find_task_by_pid_ns(..., &init_pid_ns) there
and schedule the find_task_by_pid for removal.

Signed-off-by: Pavel Emelyanov <[EMAIL PROTECTED]>

---
 Documentation/feature-removal-schedule.txt |   19 +++++++++++++++++++
 include/linux/sched.h                      |    2 +-
 init/main.c                                |    2 +-
 kernel/kgdb.c                              |    2 +-
 kernel/kthread.c                           |    2 +-
 5 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/Documentation/feature-removal-schedule.txt 
b/Documentation/feature-removal-schedule.txt
index be6c2db..1e6960d 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -264,3 +264,22 @@ Why:       These drivers are superseded by i810fb, intelfb 
and savagefb.
 Who:   Jean Delvare <[EMAIL PROTECTED]>
 
 ---------------------------
+
+What:  find_task_by_pid
+When:  2.6.26
+Why:   With pid namespaces, calling this funciton will return the
+       wrong task when called from inside a namespace.
+
+       The best way to save a task pid and find a task by this
+       pid later, is to find this task's struct pid pointer (or get
+       it directly from the task) and call pid_task() later.
+
+       If someone really needs to get a task by its pid_t, then
+       he most likely needs the find_task_by_vpid() to get the
+       task from the same namespace as the current task is in, but
+       this may be not so in general.
+
+Who:   Pavel Emelyanov <[EMAIL PROTECTED]>
+
+---------------------------
+
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 198659b..ccb9bba 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1617,7 +1617,7 @@ extern struct pid_namespace init_pid_ns;
 extern struct task_struct *find_task_by_pid_type_ns(int type, int pid,
                struct pid_namespace *ns);
 
-extern struct task_struct *find_task_by_pid(pid_t nr);
+extern struct task_struct *find_task_by_pid(pid_t nr) __deprecated;
 extern struct task_struct *find_task_by_vpid(pid_t nr);
 extern struct task_struct *find_task_by_pid_ns(pid_t nr,
                struct pid_namespace *ns);
diff --git a/init/main.c b/init/main.c
index e702632..38a16ba 100644
--- a/init/main.c
+++ b/init/main.c
@@ -437,7 +437,7 @@ static void noinline __init_refok rest_init(void)
        kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
        numa_default_policy();
        pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
-       kthreadd_task = find_task_by_pid(pid);
+       kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
        unlock_kernel();
 
        /*
diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 87b0463..6de0fd0 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -621,7 +621,7 @@ static struct task_struct *getthread(struct pt_regs *regs, 
int tid)
        if (!tid)
                return NULL;
 
-       return find_task_by_pid(tid);
+       return find_task_by_pid_ns(tid, &init_pid_ns);
 }
 
 #ifdef CONFIG_SMP
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 0ac8878..b9caa46 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -99,7 +99,7 @@ static void create_kthread(struct kthread_create_info *create)
                struct sched_param param = { .sched_priority = 0 };
                wait_for_completion(&create->started);
                read_lock(&tasklist_lock);
-               create->result = find_task_by_pid(pid);
+               create->result = find_task_by_pid_ns(pid, &init_pid_ns);
                read_unlock(&tasklist_lock);
                /*
                 * root may have changed our (kthreadd's) priority or CPU mask.
-- 
1.5.3.4

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