exit: Move oops specific logic from do_exit into make_task_dead

The beginning of do_exit has become cluttered and difficult to read as
it is filled with checks to handle things that can only happen when
the kernel is operating improperly.

Now that we have a dedicated function for cleaning up a task when the
kernel is operating improperly move the checks there.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

diff --git a/kernel/exit.c b/kernel/exit.c
index bfa513c5b2271555ba1653b8bfa7a146403754dd..d0ec6f6b41cb49bbec942361b0ed4b36537a5063 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -735,36 +735,8 @@ void __noreturn do_exit(long code)
        struct task_struct *tsk = current;
        int group_dead;
 
-       /*
-        * We can get here from a kernel oops, sometimes with preemption off.
-        * Start by checking for critical errors.
-        * Then fix up important state like USER_DS and preemption.
-        * Then do everything else.
-        */
-
        WARN_ON(blk_needs_flush_plug(tsk));
 
-       if (unlikely(in_interrupt()))
-               panic("Aiee, killing interrupt handler!");
-       if (unlikely(!tsk->pid))
-               panic("Attempted to kill the idle task!");
-
-       /*
-        * If do_exit is called because this processes oopsed, it's possible
-        * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
-        * continuing. Amongst other possible reasons, this is to prevent
-        * mm_release()->clear_child_tid() from writing to a user-controlled
-        * kernel address.
-        */
-       force_uaccess_begin();
-
-       if (unlikely(in_atomic())) {
-               pr_info("note: %s[%d] exited with preempt_count %d\n",
-                       current->comm, task_pid_nr(current),
-                       preempt_count());
-               preempt_count_set(PREEMPT_ENABLED);
-       }
-
        profile_task_exit(tsk);
        kcov_task_exit(tsk);
 
@@ -773,17 +745,6 @@ void __noreturn do_exit(long code)
 
        validate_creds_for_do_exit(tsk);
 
-       /*
-        * We're taking recursive faults here in do_exit. Safest is to just
-        * leave this task alone and wait for reboot.
-        */
-       if (unlikely(tsk->flags & PF_EXITING)) {
-               pr_alert("Fixing recursive fault but reboot is needed!\n");
-               futex_exit_recursive(tsk);
-               set_current_state(TASK_UNINTERRUPTIBLE);
-               schedule();
-       }
-
        io_uring_files_cancel();
        exit_signals(tsk);  /* sets PF_EXITING */
 
@@ -889,7 +850,46 @@ void __noreturn make_task_dead(int signr)
        /*
         * Take the task off the cpu after something catastrophic has
         * happened.
+        *
+        * We can get here from a kernel oops, sometimes with preemption off.
+        * Start by checking for critical errors.
+        * Then fix up important state like USER_DS and preemption.
+        * Then do everything else.
         */
+       struct task_struct *tsk = current;
+
+       if (unlikely(in_interrupt()))
+               panic("Aiee, killing interrupt handler!");
+       if (unlikely(!tsk->pid))
+               panic("Attempted to kill the idle task!");
+
+       /*
+        * If make_task_dead is called because this processes oopsed, it's possible
+        * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
+        * continuing. Amongst other possible reasons, this is to prevent
+        * mm_release()->clear_child_tid() from writing to a user-controlled
+        * kernel address.
+        */
+       force_uaccess_begin();
+
+       if (unlikely(in_atomic())) {
+               pr_info("note: %s[%d] exited with preempt_count %d\n",
+                       current->comm, task_pid_nr(current),
+                       preempt_count());
+               preempt_count_set(PREEMPT_ENABLED);
+       }
+
+       /*
+        * We're taking recursive faults here in make_task_dead. Safest is to just
+        * leave this task alone and wait for reboot.
+        */
+       if (unlikely(tsk->flags & PF_EXITING)) {
+               pr_alert("Fixing recursive fault but reboot is needed!\n");
+               futex_exit_recursive(tsk);
+               set_current_state(TASK_UNINTERRUPTIBLE);
+               schedule();
+       }
+
        do_exit(signr);
 }
 

diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index 25d8a88b32e5b0566723c6d8064053ae87755d50..39a1522865b53ff5fb07f47bf05a96d2d80f2285 100644 (file)
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -1044,7 +1044,7 @@ static void futex_cleanup(struct task_struct *tsk)
  * actually finished the futex cleanup. The worst case for this is that the
  * waiter runs through the wait loop until the state becomes visible.
  *
- * This is called from the recursive fault handling path in do_exit().
+ * This is called from the recursive fault handling path in make_task_dead().
  *
  * This is best effort. Either the futex exit code has run already or
  * not. If the OWNER_DIED bit has been set on the futex then the waiter can

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 5a5d192a89ac307169f203480053387745b600b4..68480f731192ebe325f607953dbdcc70d2dfbe18 100644 (file)
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -81,7 +81,7 @@ int kexec_should_crash(struct task_struct *p)
        if (crash_kexec_post_notifiers)
                return 0;
        /*
-        * There are 4 panic() calls in do_exit() path, each of which
+        * There are 4 panic() calls in make_task_dead() path, each of which
         * corresponds to each of these 4 conditions.
         */
        if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)