linux-kernel - Re: Random panic in load

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+55aFw3eJDJmRJb9pZiLk4wTN1GCRN+BsxOXV+SwqcV1SfQmQ@mail.gmail.com>
Date:	Mon, 28 Jul 2014 11:28:37 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Markus Trippelsdorf <markus@...ppelsdorf.de>
Cc:	Alexei Starovoitov <ast@...nel.org>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Michel Dänzer <michel@...nzer.net>,
	Jakub Jelinek <jakub@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Debian GCC Maintainers <debian-gcc@...ts.debian.org>,
	Debian Kernel Team <debian-kernel@...ts.debian.org>
Subject: Re: Random panic in load_balance() with 3.16-rc

On Mon, Jul 28, 2014 at 11:09 AM, Markus Trippelsdorf
<markus@...ppelsdorf.de> wrote:
>
> It shouldn't be too hard to implement a simple check for the bug in the
> next release. Just compile the gcc/testsuite/gcc.target/i386/pr61801.c
> testcase with -fcompare-debug. If gcc returns 0 then
> -fvar-tracking-assignments could safely be enabled again.

We don't really have any good infrastructure for things like this,
though. We probably *should* have a way to generate config options by
compiler version, but right now we don't. We do random ugly things
from within Makefile shell escapes (see all the helpers for this we do
in scripts/Kbuild.include, for example), and we could add yet another
one. But this is a whole new level of "ugly hack". It would be better
if we could do things like this at config time, not at build-time with
Makefile hacks.

Also, the test-case seems to be very sensitive to compiler options: it
passes with "-O", but fails with "-O2" or "-Os" for me. So I wonder
how reliable it is in the face of compiler version differences (ie is
it really robust wrt the bug actually being *fixed*, or is it a bit of
a happenstance)

          Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/