ftrace: Optimize the allocation for mcount entries

stable inclusion
from stable-v5.10.156
commit 6ed60c60ec9050345f024b7e9c7c0db6e8cd31d2
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7MCG1

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6ed60c60ec9050345f024b7e9c7c0db6e8cd31d2

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

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: Nsanglipeng <sanglipeng1@jd.com>

kernel/trace/ftrace.c

@@ -3180,7 +3180,7 @@ 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;
 	}