[PATCH 04/11] x86/fault: Document the locking in the fault_signal_pending() path

[Andy Lutomirski]

If fault_signal_pending() returns true, then the core mm has unlocked the
mm for us.  Add a comment to help future readers of this code.

Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
 arch/x86/mm/fault.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 87d30daa5e0a..b52064920f0d 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1343,8 +1343,11 @@ void do_user_addr_fault(struct pt_regs *regs,
 	 */
 	fault = handle_mm_fault(vma, address, flags, regs);
 
-	/* Quick path to respond to signals */
 	if (fault_signal_pending(fault, regs)) {
+		/*
+		 * Quick path to respond to signals.  The core mm code
+		 * has unlocked the mm for us if we get here.
+		 */
 		if (!user_mode(regs))
 			no_context(regs, error_code, address, SIGBUS,
 				   BUS_ADRERR);
-- 
2.29.2