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-rw-r--r--include/linux/mm_types.h2
-rw-r--r--include/linux/sched.h5
-rw-r--r--kernel/fork.c50
-rw-r--r--mm/oom_kill.c8
4 files changed, 48 insertions, 17 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 1fda9c99ef95..d553855503e6 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -12,6 +12,7 @@
#include <linux/cpumask.h>
#include <linux/uprobes.h>
#include <linux/page-flags-layout.h>
+#include <linux/workqueue.h>
#include <asm/page.h>
#include <asm/mmu.h>
@@ -513,6 +514,7 @@ struct mm_struct {
#ifdef CONFIG_HUGETLB_PAGE
atomic_long_t hugetlb_usage;
#endif
+ struct work_struct async_put_work;
};
static inline void mm_init_cpumask(struct mm_struct *mm)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 40eabf176ce2..479e3cade7e9 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2730,6 +2730,11 @@ static inline void mmdrop(struct mm_struct * mm)
/* mmput gets rid of the mappings and all user-space */
extern void mmput(struct mm_struct *);
+/* same as above but performs the slow path from the async kontext. Can
+ * be called from the atomic context as well
+ */
+extern void mmput_async(struct mm_struct *);
+
/* Grab a reference to a task's mm, if it is not already going away */
extern struct mm_struct *get_task_mm(struct task_struct *task);
/*
diff --git a/kernel/fork.c b/kernel/fork.c
index 3e8451527cbe..8fbed7194af1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -699,6 +699,26 @@ void __mmdrop(struct mm_struct *mm)
}
EXPORT_SYMBOL_GPL(__mmdrop);
+static inline void __mmput(struct mm_struct *mm)
+{
+ VM_BUG_ON(atomic_read(&mm->mm_users));
+
+ uprobe_clear_state(mm);
+ exit_aio(mm);
+ ksm_exit(mm);
+ khugepaged_exit(mm); /* must run before exit_mmap */
+ exit_mmap(mm);
+ set_mm_exe_file(mm, NULL);
+ if (!list_empty(&mm->mmlist)) {
+ spin_lock(&mmlist_lock);
+ list_del(&mm->mmlist);
+ spin_unlock(&mmlist_lock);
+ }
+ if (mm->binfmt)
+ module_put(mm->binfmt->module);
+ mmdrop(mm);
+}
+
/*
* Decrement the use count and release all resources for an mm.
*/
@@ -706,24 +726,24 @@ void mmput(struct mm_struct *mm)
{
might_sleep();
+ if (atomic_dec_and_test(&mm->mm_users))
+ __mmput(mm);
+}
+EXPORT_SYMBOL_GPL(mmput);
+
+static void mmput_async_fn(struct work_struct *work)
+{
+ struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work);
+ __mmput(mm);
+}
+
+void mmput_async(struct mm_struct *mm)
+{
if (atomic_dec_and_test(&mm->mm_users)) {
- uprobe_clear_state(mm);
- exit_aio(mm);
- ksm_exit(mm);
- khugepaged_exit(mm); /* must run before exit_mmap */
- exit_mmap(mm);
- set_mm_exe_file(mm, NULL);
- if (!list_empty(&mm->mmlist)) {
- spin_lock(&mmlist_lock);
- list_del(&mm->mmlist);
- spin_unlock(&mmlist_lock);
- }
- if (mm->binfmt)
- module_put(mm->binfmt->module);
- mmdrop(mm);
+ INIT_WORK(&mm->async_put_work, mmput_async_fn);
+ schedule_work(&mm->async_put_work);
}
}
-EXPORT_SYMBOL_GPL(mmput);
/**
* set_mm_exe_file - change a reference to the mm's executable file
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index c0376efa79ec..c0e37dd1422f 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -446,7 +446,6 @@ static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait);
static struct task_struct *oom_reaper_list;
static DEFINE_SPINLOCK(oom_reaper_lock);
-
static bool __oom_reap_task(struct task_struct *tsk)
{
struct mmu_gather tlb;
@@ -520,7 +519,12 @@ static bool __oom_reap_task(struct task_struct *tsk)
*/
set_bit(MMF_OOM_REAPED, &mm->flags);
out:
- mmput(mm);
+ /*
+ * Drop our reference but make sure the mmput slow path is called from a
+ * different context because we shouldn't risk we get stuck there and
+ * put the oom_reaper out of the way.
+ */
+ mmput_async(mm);
return ret;
}