From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:42276 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752164AbcFEU40 (ORCPT ); Sun, 5 Jun 2016 16:56:26 -0400 Subject: Patch "gcov: disable tree-loop-im to reduce stack usage" has been added to the 4.4-stable tree To: arnd@arndb.de, gregkh@linuxfoundation.org, mmarek@suse.com, oberpar@linux.vnet.ibm.com Cc: , From: Date: Sun, 05 Jun 2016 13:56:26 -0700 Message-ID: <1465160186198109@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled gcov: disable tree-loop-im to reduce stack usage to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: gcov-disable-tree-loop-im-to-reduce-stack-usage.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From c87bf431448b404a6ef5fbabd74c0e3e42157a7f Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Mon, 25 Apr 2016 17:35:30 +0200 Subject: gcov: disable tree-loop-im to reduce stack usage From: Arnd Bergmann 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: Greg Kroah-Hartman --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/Makefile +++ b/Makefile @@ -364,7 +364,7 @@ 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. Patches currently in stable-queue which might be from arnd@arndb.de are queue-4.4/gcov-disable-tree-loop-im-to-reduce-stack-usage.patch