mm: export symbol find_get_task_by_vpid

maillist inclusion
category: feature
bugzilla: 51855
CVE: NA

Reference: https://jpbrucker.net/git/linux/commit/?h=sva/2021-03-01&id=176b3454e53ffdd4a4f6dbc51f128f1f35a1b357

---------------------------------------------

Userspace drivers implemented with VFIO might want to bind sub-processes
to their devices. In a VFIO ioctl, they provide a pid that is used to find
a task and its mm. Since VFIO can be built as a module, export the
find_get_task_by_vpid symbol.
Signed-off-by: NJean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: NLijun Fang <fanglijun3@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/pid.c

@@ -434,6 +434,7 @@ struct task_struct *find_get_task_by_vpid(pid_t nr)
 
 	return task;
 }
+EXPORT_SYMBOL_GPL(find_get_task_by_vpid);
 
 struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
 {