ftrace: Optimize the allocation for mcount entries

stable inclusion
from stable-v4.19.267
commit d110bb57a7e9831465aa3abb6c0d1cc658b05fbe
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I63UEU
CVE: NA

--------------------------------

commit bcea02b0 upstream.

If we can't allocate this size, try something smaller with half of the
size. Its order should be decreased by one instead of divided by two.

Link: https://lkml.kernel.org/r/20221109094434.84046-3-wangwensheng4@huawei.com

Cc: <mhiramat@kernel.org>
Cc: <mark.rutland@arm.com>
Cc: stable@vger.kernel.org
Fixes: a7900875 ("ftrace: Allocate the mcount record pages as groups")
Signed-off-by: NWang Wensheng <wangwensheng4@huawei.com>
Signed-off-by: NSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

kernel/trace/ftrace.c

@@ -3023,7 +3023,7 @@ static int ftrace_allocate_records(struct ftrace_page *pg, int count)
 		/* if we can't allocate this size, try something smaller */
 		if (!order)
 			return -ENOMEM;
-		order >>= 1;
+		order--;
 		goto again;
 	}