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-rw-r--r--include/linux/mm_types.h2
-rw-r--r--include/linux/sched.h14
-rw-r--r--kernel/fork.c6
3 files changed, 19 insertions, 3 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 903200f4ec41..4a8acedf4b7d 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -515,9 +515,7 @@ struct mm_struct {
#ifdef CONFIG_HUGETLB_PAGE
atomic_long_t hugetlb_usage;
#endif
-#ifdef CONFIG_MMU
struct work_struct async_put_work;
-#endif
};
static inline void mm_init_cpumask(struct mm_struct *mm)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 67ea79610e67..c4b588358296 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2877,6 +2877,20 @@ static inline void mmdrop(struct mm_struct *mm)
__mmdrop(mm);
}
+static inline void mmdrop_async_fn(struct work_struct *work)
+{
+ struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work);
+ __mmdrop(mm);
+}
+
+static inline void mmdrop_async(struct mm_struct *mm)
+{
+ if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
+ INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
+ schedule_work(&mm->async_put_work);
+ }
+}
+
static inline bool mmget_not_zero(struct mm_struct *mm)
{
return atomic_inc_not_zero(&mm->mm_users);
diff --git a/kernel/fork.c b/kernel/fork.c
index 48cafe787b75..5650e35dda43 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -359,8 +359,12 @@ static inline void free_signal_struct(struct signal_struct *sig)
{
taskstats_tgid_free(sig);
sched_autogroup_exit(sig);
+ /*
+ * __mmdrop is not safe to call from softirq context on x86 due to
+ * pgd_dtor so postpone it to the async context
+ */
if (sig->oom_mm)
- mmdrop(sig->oom_mm);
+ mmdrop_async(sig->oom_mm);
kmem_cache_free(signal_cachep, sig);
}