pstore/ram: Rate-limit "uncorrectable error in header" message

There is a quite huge "uncorrectable error in header" flood in KMSG
on a clean system boot since there is no pstore buffer saved in RAM.
Let's silence the redundant noisy messages by rate-limiting the printk
message. Now there are maximum 10 messages printed repeatedly instead
of 35+.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210302095850.30894-1-digetx@gmail.com

fs/pstore/ram_core.c

@@ -246,7 +246,7 @@ static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 		pr_info("error in header, %d\n", numerr);
 		prz->corrected_bytes += numerr;
 	} else if (numerr < 0) {
-		pr_info("uncorrectable error in header\n");
+		pr_info_ratelimited("uncorrectable error in header\n");
 		prz->bad_blocks++;
 	}