exit/exec: Seperate mm_release()

commit 4610ba7ad877fafc0a25a30c6c82015304120426 upstream.

mm_release() contains the futex exit handling. mm_release() is called from
do_exit()->exit_mm() and from exec()->exec_mm().

In the exit_mm() case PF_EXITING and the futex state is updated. In the
exec_mm() case these states are not touched.

As the futex exit code needs further protections against exit races, this
needs to be split into two functions.

Preparatory only, no functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.240518241@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/exec.c b/fs/exec.c
index 4623fc3ac86b8d913f0fb4f1a4baca2d45e22c95..7def97f6aac24e9b2d1b29c821e9537fae41e367 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1007,7 +1007,7 @@ static int exec_mmap(struct mm_struct *mm)
        /* Notify parent that we're no longer interested in the old VM */
        tsk = current;
        old_mm = current->mm;
-       mm_release(tsk, old_mm);
+       exec_mm_release(tsk, old_mm);
 
        if (old_mm) {
                sync_mm_rss(old_mm);

diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 9f7cc1d7ec4a89a9e293a4b6c7f67f3a2f865217..efb9e12e7f917602b68b87dcb19cd3782ba171d1 100644 (file)
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -125,8 +125,10 @@ extern struct mm_struct *get_task_mm(struct task_struct *task);
  * succeeds.
  */
 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
-/* Remove the current tasks stale references to the old mm_struct */
-extern void mm_release(struct task_struct *, struct mm_struct *);
+/* Remove the current tasks stale references to the old mm_struct on exit() */
+extern void exit_mm_release(struct task_struct *, struct mm_struct *);
+/* Remove the current tasks stale references to the old mm_struct on exec() */
+extern void exec_mm_release(struct task_struct *, struct mm_struct *);
 
 #ifdef CONFIG_MEMCG
 extern void mm_update_next_owner(struct mm_struct *mm);

diff --git a/kernel/exit.c b/kernel/exit.c
index c5435a2d37c3325d3abd864fa430f8584b2fa86d..844678c57756cc47880e3ed8de1c6f71108f69f9 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -497,7 +497,7 @@ static void exit_mm(void)
        struct mm_struct *mm = current->mm;
        struct core_state *core_state;
 
-       mm_release(current, mm);
+       exit_mm_release(current, mm);
        if (!mm)
                return;
        sync_mm_rss(mm);

diff --git a/kernel/fork.c b/kernel/fork.c
index 1dc6b9ecc33ac181b81b0fa0a97dc3c73acfa3da..768a57aaf00d11e25f408dfd754c34f407ce6608 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1132,7 +1132,7 @@ static int wait_for_vfork_done(struct task_struct *child,
  * restoring the old one. . .
  * Eric Biederman 10 January 1998
  */
-void mm_release(struct task_struct *tsk, struct mm_struct *mm)
+static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 {
        /* Get rid of any futexes when releasing the mm */
        futex_mm_release(tsk);
@@ -1169,6 +1169,16 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
                complete_vfork_done(tsk);
 }
 
+void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
+{
+       mm_release(tsk, mm);
+}
+
+void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
+{
+       mm_release(tsk, mm);
+}
+
 /*
  * Allocate a new mm structure and copy contents from the
  * mm structure of the passed in task structure.