Patch "x86: mm: move mmap_sem unlock from mm_fault_error() to caller" has been added to the 3.14-stable tree

@@ -833,11 +833,8 @@ do_sigbus(struct pt_regs *regs, unsigned
 	  unsigned int fault)
 {
 	struct task_struct *tsk = current;
-	struct mm_struct *mm = tsk->mm;
 	int code = BUS_ADRERR;
 
-	up_read(&mm->mmap_sem);
-
 	/* Kernel mode? Handle exceptions or die: */
 	if (!(error_code & PF_USER)) {
 		no_context(regs, error_code, address, SIGBUS, BUS_ADRERR);

@@ -868,7 +865,6 @@ mm_fault_error(struct pt_regs *regs, uns
 	       unsigned long address, unsigned int fault)
 {
 	if (fatal_signal_pending(current) && !(error_code & PF_USER)) {
-		up_read(&current->mm->mmap_sem);
 		no_context(regs, error_code, address, 0, 0);
 		return;
 	}

@@ -876,14 +872,11 @@ mm_fault_error(struct pt_regs *regs, uns
 	if (fault & VM_FAULT_OOM) {
 		/* Kernel mode? Handle exceptions or die: */
 		if (!(error_code & PF_USER)) {
-			up_read(&current->mm->mmap_sem);
 			no_context(regs, error_code, address,
 				   SIGSEGV, SEGV_MAPERR);
 			return;
 		}
 
-		up_read(&current->mm->mmap_sem);
-
 		/*
 		 * We ran out of memory, call the OOM killer, and return the
 		 * userspace (which will retry the fault, or kill us if we got

@@ -1218,6 +1211,7 @@ good_area:
 		return;
 
 	if (unlikely(fault & VM_FAULT_ERROR)) {
+		up_read(&mm->mmap_sem);
 		mm_fault_error(regs, error_code, address, fault);
 		return;
 	}