[PATCH v2] kernel/fork: Update obsolete use_mm references to kthread_use_mm

["mingzhu.wang(王明珠)" <mingzhu.wang@transsion.com>]

The comment for get_task_mm() in kernel/fork.c incorrectly
references the deprecated function `use_mm()`, which has been renamed
to `kthread_use_mm()` in kernel/kthread.c.

This patch updates the documentation to reflect the current function
names, ensuring accuracy when developers refer to the kernel thread
memory context API.

No functional changes were introduced.

Signed-off-by: mingzhu.wang <mingzhu.wang@transsion.com>
---
v2:
- Unwrap the comment line in kernel/fork.c as requested by Michal Hocko.
- Wrap commit message lines to 75 characters as suggested by David Hildenbrand.

 kernel/fork.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index b1f3915d5f8e..0c5f985cf369 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1356,7 +1356,7 @@ struct file *get_task_exe_file(struct task_struct *task)
  * @task: The task.
  *
  * Returns %NULL if the task has no mm.  Checks PF_KTHREAD (meaning
- * this kernel workthread has transiently adopted a user mm with use_mm,
+ * this kernel workthread has transiently adopted a user mm with kthread_use_mm,
  * to do its AIO) is not set and if so returns a reference to it, after
  * bumping up the use count.  User must release the mm via mmput()
  * after use.  Typically used by /proc and ptrace.
--
2.34.1