From: Jérôme Glisse <jglisse@xxxxxxxxxx>
This code was lost in translation at one point. This properly call
mmu_notifier_unregister_no_release() once last user is gone. This
fix the zombie mm_struct as without this patch we do not drop the
refcount we have on it.
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Evgeny Baskakov <ebaskakov@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Mark Hairgrove <mhairgrove@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
---
mm/hmm.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/mm/hmm.c b/mm/hmm.c
index 6088fa6ed137..667944630dc9 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -244,10 +244,29 @@ EXPORT_SYMBOL(hmm_mirror_register);
void hmm_mirror_unregister(struct hmm_mirror *mirror)
{
struct hmm *hmm = mirror->hmm;
+ struct mm_struct *mm = NULL;
+ bool unregister = false;
down_write(&hmm->mirrors_sem);
list_del_init(&mirror->list);
+ unregister = list_empty(&hmm->mirrors);
up_write(&hmm->mirrors_sem);
+
+ if (!unregister)
+ return;
+
+ spin_lock(&hmm->mm->page_table_lock);
+ if (hmm->mm->hmm == hmm) {
+ mm = hmm->mm;
+ mm->hmm = NULL;
+ }
+ spin_unlock(&hmm->mm->page_table_lock);
+
+ if (mm == NULL)
+ return;
+
+ mmu_notifier_unregister_no_release(&hmm->mmu_notifier, mm);
+ kfree(hmm);
}
EXPORT_SYMBOL(hmm_mirror_unregister);
--
2.14.3
