Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758510AbcJQIPN (ORCPT ); Mon, 17 Oct 2016 04:15:13 -0400 Received: from mx2.suse.de ([195.135.220.15]:48788 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933745AbcJQINt (ORCPT ); Mon, 17 Oct 2016 04:13:49 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Arnd Bergmann , Michal Marek , Jiri Slaby Subject: [PATCH 3.12 01/84] gcov: disable tree-loop-im to reduce stack usage Date: Mon, 17 Oct 2016 09:50:48 +0200 Message-Id: <2d291fde5f706ac081e8cfc0ebe7e31dd534dfe7.1476690493.git.jslaby@suse.cz> X-Mailer: git-send-email 2.10.1 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1803 Lines: 52 From: Arnd Bergmann 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit c87bf431448b404a6ef5fbabd74c0e3e42157a7f upstream. Enabling CONFIG_GCOV_PROFILE_ALL produces us a lot of warnings like lib/lz4/lz4hc_compress.c: In function 'lz4_compresshcctx': lib/lz4/lz4hc_compress.c:514:1: warning: the frame size of 1504 bytes is larger than 1024 bytes [-Wframe-larger-than=] After some investigation, I found that this behavior started with gcc-4.9, and opened https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69702. A suggested workaround for it is to use the -fno-tree-loop-im flag that turns off one of the optimization stages in gcc, so the code runs a little slower but does not use excessive amounts of stack. We could make this conditional on the gcc version, but I could not find an easy way to do this in Kbuild and the benefit would be fairly small, given that most of the gcc version in production are affected now. I'm marking this for 'stable' backports because it addresses a bug with code generation in gcc that exists in all kernel versions with the affected gcc releases. Signed-off-by: Arnd Bergmann Acked-by: Peter Oberparleiter Signed-off-by: Michal Marek Signed-off-by: Jiri Slaby --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Makefile b/Makefile index a90b363b3493..4c1baa9b6bae 100644 --- a/Makefile +++ b/Makefile @@ -347,7 +347,7 @@ AFLAGS_MODULE = LDFLAGS_MODULE = CFLAGS_KERNEL = AFLAGS_KERNEL = -CFLAGS_GCOV = -fprofile-arcs -ftest-coverage +CFLAGS_GCOV = -fprofile-arcs -ftest-coverage -fno-tree-loop-im # Use USERINCLUDE when you must reference the UAPI directories only. -- 2.10.1