Bug 519172 (PR61801)

Summary:	sys-devel/gcc-4.9.0 - sched2 miscompiles syscall sequence with -g Random panic in load_balance() with kernel 3.16-rc
Product:	Gentoo Linux	Reporter:	Mark Wright <gienah>
Component:	[OLD] Core system	Assignee:	Gentoo Toolchain Maintainers <toolchain>
Status:	RESOLVED FIXED
Severity:	normal	Keywords:	PATCH
Priority:	Normal
Version:	unspecified
Hardware:	All
OS:	Linux
URL:	https://gcc.gnu.org/PR61801
See Also:	https://bugs.gentoo.org/show_bug.cgi?id=527480 https://bugs.gentoo.org/show_bug.cgi?id=547420
Whiteboard:
Package list:		Runtime testing required:	---
Bug Depends on:
Bug Blocks:	915000
Attachments:	gcc 4.9.0 patch from upstream

Description Mark Wright gentoo-dev

2014-08-06 00:49:04 UTC

Created attachment 382364 [details, diff]
gcc 4.9.0 patch from upstream

Linus colourfully describes how gcc 4.9.0 and the compiler versions 4.5.0 (when debug_insn came in) to 4.8.3 and 4.9.0 and 4.9.1 generate incorrect code with -g
leading to random kernel crashes:

http://lkml.iu.edu/hypermail/linux/kernel/1407.3/00650.html

The gcc bug report including the fix:

Bug 61801 - sched2 miscompiles syscall sequence with -g
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801

The attached patch contains the fix from upstream:

https://gcc.gnu.org/viewcvs/gcc/branches/gcc-4_9-branch/gcc/sched-deps.c?r1=209304&r2=212739&pathrev=212739

Comment 1 Ryan Hill (RETIRED) gentoo-dev

2014-08-07 00:39:57 UTC

Fixed in 4.9.1 p1.0 so far.

Comment 2 Anthony Basile gentoo-dev

2014-10-30 23:16:22 UTC

(In reply to Ryan Hill from comment #1)
> Fixed in 4.9.1 p1.0 so far.

This fix is now in 4.9.2 and we no longer need patch/91_all_4.9.2_pr61801.patch.  See bug #527480.  If someone wants to produce the new 4.9.2 patchset.

Comment 3 SpanKY gentoo-dev

2014-11-01 06:44:59 UTC

this is fixed in Gentoo's gcc-4.9.1 already