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Bug 519172 (PR61801) - sys-devel/gcc-4.9.0 - sched2 miscompiles syscall sequence with -g Random panic in load_balance() with kernel 3.16-rc
Summary: sys-devel/gcc-4.9.0 - sched2 miscompiles syscall sequence with -g Random pani...
Status: RESOLVED FIXED
Alias: PR61801
Product: Gentoo Linux
Classification: Unclassified
Component: [OLD] Core system (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Gentoo Toolchain Maintainers
URL: https://gcc.gnu.org/PR61801
Whiteboard:
Keywords: PATCH
Depends on:
Blocks: 915000
  Show dependency tree
 
Reported: 2014-08-06 00:49 UTC by Mark Wright
Modified: 2023-10-01 06:04 UTC (History)
0 users

See Also:
Package list:
Runtime testing required: ---

Attachments
gcc 4.9.0 patch from upstream (gcc-4.9.0-Bug-61801-sched2-miscompiles-syscall-sequence-with-g.patch,628 bytes, patch)
2014-08-06 00:49 UTC, Mark Wright 		Details | Diff
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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