signal: Move MMCID exit out of sighand lock

There is no need anymore to keep this under sighand lock as the current
code and the upcoming replacement are not depending on the exit state of a
task anymore.

That allows to use a mutex in the exit path.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251119172549.706439391@linutronix.de

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 64f080d6ed6e4b333edf2a26e36254e9e86f0dac..c411ae021bc5523c1a3dad53f487a30e49e8c40d 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2298,7 +2298,7 @@ static __always_inline void alloc_tag_restore(struct alloc_tag *tag, struct allo
 void sched_mm_cid_before_execve(struct task_struct *t);
 void sched_mm_cid_after_execve(struct task_struct *t);
 void sched_mm_cid_fork(struct task_struct *t);
-void sched_mm_cid_exit_signals(struct task_struct *t);
+void sched_mm_cid_exit(struct task_struct *t);
 static inline int task_mm_cid(struct task_struct *t)
 {
        return t->mm_cid.cid;
@@ -2307,7 +2307,7 @@ static inline int task_mm_cid(struct task_struct *t)
 static inline void sched_mm_cid_before_execve(struct task_struct *t) { }
 static inline void sched_mm_cid_after_execve(struct task_struct *t) { }
 static inline void sched_mm_cid_fork(struct task_struct *t) { }
-static inline void sched_mm_cid_exit_signals(struct task_struct *t) { }
+static inline void sched_mm_cid_exit(struct task_struct *t) { }
 static inline int task_mm_cid(struct task_struct *t)
 {
        /*

diff --git a/kernel/exit.c b/kernel/exit.c
index 9f74e8f1c431b6aa6e391ff71aadf9895a3857ae..324616f690b7b1c77a11fdd8fceda060237eec04 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -910,6 +910,7 @@ void __noreturn do_exit(long code)
        user_events_exit(tsk);
 
        io_uring_files_cancel();
+       sched_mm_cid_exit(tsk);
        exit_signals(tsk);  /* sets PF_EXITING */
 
        seccomp_filter_release(tsk);

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9a114b6f6a6fddab9645bdea4e9149bcdf66c250..3fdf90a7074d80828e5f9d93ddde98c80dfaacdd 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -10392,7 +10392,7 @@ static inline void mm_update_cpus_allowed(struct mm_struct *mm, const struct cpu
        WRITE_ONCE(mm->mm_cid.nr_cpus_allowed, weight);
 }
 
-void sched_mm_cid_exit_signals(struct task_struct *t)
+void sched_mm_cid_exit(struct task_struct *t)
 {
        struct mm_struct *mm = t->mm;
 
@@ -10410,7 +10410,7 @@ void sched_mm_cid_exit_signals(struct task_struct *t)
 /* Deactivate MM CID allocation across execve() */
 void sched_mm_cid_before_execve(struct task_struct *t)
 {
-       sched_mm_cid_exit_signals(t);
+       sched_mm_cid_exit(t);
 }
 
 /* Reactivate MM CID after successful execve() */

diff --git a/kernel/signal.c b/kernel/signal.c
index fe9190d84f281e650a2f2b356f6fe692e22dadd4..e42b8bd6922fcb08a09de7b35e8160a5acf79133 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3125,7 +3125,6 @@ void exit_signals(struct task_struct *tsk)
        cgroup_threadgroup_change_begin(tsk);
 
        if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
-               sched_mm_cid_exit_signals(tsk);
                tsk->flags |= PF_EXITING;
                cgroup_threadgroup_change_end(tsk);
                return;
@@ -3136,7 +3135,6 @@ void exit_signals(struct task_struct *tsk)
         * From now this task is not visible for group-wide signals,
         * see wants_signal(), do_signal_stop().
         */
-       sched_mm_cid_exit_signals(tsk);
        tsk->flags |= PF_EXITING;
 
        cgroup_threadgroup_change_end(tsk);