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-rw-r--r--mm/memory.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c
index e158f7ac6730..c717b5bcc80e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3910,8 +3910,18 @@ int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
* further.
*/
if (unlikely((current->flags & PF_KTHREAD) && !(ret & VM_FAULT_ERROR)
- && test_bit(MMF_UNSTABLE, &vma->vm_mm->flags)))
+ && test_bit(MMF_UNSTABLE, &vma->vm_mm->flags))) {
+
+ /*
+ * We are going to enforce SIGBUS but the PF path might have
+ * dropped the mmap_sem already so take it again so that
+ * we do not break expectations of all arch specific PF paths
+ * and g-u-p
+ */
+ if (ret & VM_FAULT_RETRY)
+ down_read(&vma->vm_mm->mmap_sem);
ret = VM_FAULT_SIGBUS;
+ }
return ret;
}