coredump: fix wrong comments on core limits of pipe coredump case

In commit 898b374 ("exec: replace call_usermodehelper_pipe with use
of umh init function and resolve limit"), the core limits recursive
check value was changed from 0 to 1, but the corresponding comments were
not updated.

Signed-off-by: Jovi Zhang <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Neil Horman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/exec.c

@@ -2174,15 +2174,16 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
 		}
 
 		if (cprm.limit == 1) {
-			/*
+			/* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
+			 *
 			 * Normally core limits are irrelevant to pipes, since
 			 * we're not writing to the file system, but we use
-			 * cprm.limit of 1 here as a speacial value. Any
-			 * non-1 limit gets set to RLIM_INFINITY below, but
-			 * a limit of 0 skips the dump.  This is a consistent
-			 * way to catch recursive crashes.  We can still crash
-			 * if the core_pattern binary sets RLIM_CORE =  !1
-			 * but it runs as root, and can do lots of stupid things
+			 * cprm.limit of 1 here as a speacial value, this is a
+			 * consistent way to catch recursive crashes.
+			 * We can still crash if the core_pattern binary sets
+			 * RLIM_CORE = !1, but it runs as root, and can do
+			 * lots of stupid things.
+			 *
 			 * Note that we use task_tgid_vnr here to grab the pid
 			 * of the process group leader.  That way we get the
 			 * right pid if a thread in a multi-threaded