We only use ->exit_mm to look up dumpability and the ->user_mm; we don't need to keep the PGD alive for this. mmgrab() is also inconvenient here, because it means that we need to use mmdrop_async() when dropping the reference to the mm from an RCU callback. Use mm_ref() instead of mmgrab() to make things neater. Signed-off-by: Jann Horn <jannh@xxxxxxxxxx> --- kernel/exit.c | 2 +- kernel/fork.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 97253ef33486..03ba6d13ef1e 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -476,7 +476,7 @@ static void exit_mm(void) /* more a memory barrier than a real lock */ task_lock(current); current->mm = NULL; - mmgrab(mm); /* for current->exit_mm */ + mm_ref(mm); /* for current->exit_mm */ current->exit_mm = mm; mmap_read_unlock(mm); enter_lazy_tlb(mm, current); diff --git a/kernel/fork.c b/kernel/fork.c index 59c119b03351..4383bf055b40 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -720,7 +720,7 @@ void free_task(struct task_struct *tsk) if (tsk->flags & PF_KTHREAD) free_kthread_struct(tsk); if (tsk->exit_mm) - mmdrop_async(tsk->exit_mm); + mm_unref(tsk->exit_mm); free_task_struct(tsk); } EXPORT_SYMBOL(free_task); -- 2.29.0.rc1.297.gfa9743e501-goog
