1 files changed, 29 insertions, 8 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 52e725d4a866..beb31725f7e2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -799,6 +799,29 @@ struct file *get_mm_exe_file(struct mm_struct *mm)
 EXPORT_SYMBOL(get_mm_exe_file);
 
 /**
+ * get_task_exe_file - acquire a reference to the task's executable file
+ *
+ * Returns %NULL if task's mm (if any) has no associated executable file or
+ * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
+ * User must release file via fput().
+ */
+struct file *get_task_exe_file(struct task_struct *task)
+{
+        struct file *exe_file = NULL;
+        struct mm_struct *mm;
+
+        task_lock(task);
+        mm = task->mm;
+        if (mm) {
+                if (!(task->flags & PF_KTHREAD))
+                        exe_file = get_mm_exe_file(mm);
+        }
+        task_unlock(task);
+        return exe_file;
+}
+EXPORT_SYMBOL(get_task_exe_file);
+
+/**
  * get_task_mm - acquire a reference to the task's mm
  *
  * Returns %NULL if the task has no mm.  Checks PF_KTHREAD (meaning
@@ -913,14 +936,12 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
         deactivate_mm(tsk, mm);
 
         /*
-         * If we're exiting normally, clear a user-space tid field if
-         * requested.  We leave this alone when dying by signal, to leave
-         * the value intact in a core dump, and to save the unnecessary
-         * trouble, say, a killed vfork parent shouldn't touch this mm.
-         * Userland only wants this done for a sys_exit.
+         * Signal userspace if we're not exiting with a core dump
+         * because we want to leave the value intact for debugging
+         * purposes.
          */
         if (tsk->clear_child_tid) {
-                if (!(tsk->flags & PF_SIGNALED) &&
+                if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) &&
                     atomic_read(&mm->mm_users) > 1) {
                         /*
                          * We don't check the error code - if userspace has
@@ -1404,7 +1425,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         p->real_start_time = ktime_get_boot_ns();
         p->io_context = NULL;
         p->audit_context = NULL;
-        threadgroup_change_begin(current);
         cgroup_fork(p);
 #ifdef CONFIG_NUMA
         p->mempolicy = mpol_dup(p->mempolicy);
@@ -1556,6 +1576,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         INIT_LIST_HEAD(&p->thread_group);
         p->task_works = NULL;
 
+        threadgroup_change_begin(current);
         /*
          * Ensure that the cgroup subsystem policies allow the new process to be
          * forked. It should be noted the the new process's css_set can be changed
@@ -1656,6 +1677,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 bad_fork_cancel_cgroup:
         cgroup_cancel_fork(p);
 bad_fork_free_pid:
+        threadgroup_change_end(current);
         if (pid != &init_struct_pid)
                 free_pid(pid);
 bad_fork_cleanup_thread:
@@ -1688,7 +1710,6 @@ bad_fork_cleanup_policy:
         mpol_put(p->mempolicy);
 bad_fork_cleanup_threadgroup_lock:
 #endif
-        threadgroup_change_end(current);
         delayacct_tsk_free(p);
 bad_fork_cleanup_count:
         atomic_dec(&p->cred->user->processes);