From: Nathan_Lynch@mentor•com (Nathan Lynch)
To: linux-arm-kernel@lists•infradead.org
Subject: RCU bug with v3.17-rc3 ?
Date: Fri, 10 Oct 2014 20:44:33 -0500 [thread overview]
Message-ID: <54388B81.5020306@mentor.com> (raw)
In-Reply-To: <20141010162531.GL12379@n2100.arm.linux.org.uk>
On 10/10/2014 11:25 AM, Russell King - ARM Linux wrote:
>
> Right, so GCC 4.8.{1,2} are totally unsuitable for kernel building (and
> it seems that this has been known about for some time.)
Looking at http://gcc.gnu.org/PR58854 it seems that all 4.8.x for x < 3
are affected, as well as 4.9.0.
> We can blacklist these GCC versions quite easily. We already have GCC
> 3.3 blacklisted, and it's trivial to add others. I would want to include
> some proper details about the bug, just like the other existing entries
> we already have in asm-offsets.c, where we name the functions that the
> compiler is known to break where appropriate.
Before blacklisting anything, it's worth considering that simple version
checks would break existing pre-4.8.3 compilers that have been patched
for PR58854. It looks like Yocto and Buildroot issued releases with
patched 4.8.2 compilers well before the (fixed) 4.8.3 release. I think
the most we can reasonably do without breaking some correctly-behaving
toolchains is to emit a warning.
Hopefully nobody's still using gcc 4.8 from the Linaro 2013.11 toolchain
release -- since it's a 4.8.3 prerelease from before the fix was
committed you'll get GCC_VERSION == 40803 but still generate bad code.
> However, I'm rather annoyed that there are people here who have known
> for some time that GCC 4.8.1 and GCC 4.8.2 _can_ lead to filesystem
> corruption, and have sat on their backsides doing nothing about getting
> it blacklisted for something like a year.
Mea culpa, although I hadn't drawn the connection to FS corruption
reports until now. I have known about the issue for some time, but
figured the prevalence of the fix in downstream projects largely
mitigated the issue.
next prev parent reply other threads:[~2014-10-11 1:44 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20140904184021.GA13421@saruman.home>
[not found] ` <20140904191642.GJ5001@linux.vnet.ibm.com>
[not found] ` <20140904192535.GJ13421@saruman.home>
[not found] ` <20140904200403.GL13421@saruman.home>
[not found] ` <20140905213216.GD5001@linux.vnet.ibm.com>
2014-10-08 17:13 ` RCU bug with v3.17-rc3 ? Felipe Balbi
2014-10-08 17:57 ` Felipe Balbi
2014-10-08 21:29 ` Felipe Balbi
2014-10-09 16:01 ` Johannes Weiner
2014-10-09 16:26 ` Felipe Balbi
2014-10-09 20:35 ` Felipe Balbi
2014-10-09 20:41 ` Rabin Vincent
2014-10-09 20:46 ` Felipe Balbi
2014-10-09 21:07 ` Felipe Balbi
2014-10-10 13:57 ` Felipe Balbi
2014-10-10 16:25 ` Russell King - ARM Linux
2014-10-11 1:44 ` Nathan Lynch [this message]
2014-10-11 2:40 ` Peter Hurley
2014-10-11 3:54 ` Peter Chen
2014-10-11 14:16 ` Russell King - ARM Linux
2014-10-11 14:51 ` Otavio Salvador
2014-10-11 18:15 ` Peter Hurley
2014-10-11 14:14 ` Russell King - ARM Linux
2014-10-11 19:27 ` Nathan Lynch
2014-10-13 9:11 ` David Laight
2014-10-13 11:43 ` Russell King - ARM Linux
2014-10-14 2:06 ` Greg KH
2014-10-14 10:27 ` Peter Hurley
2014-10-15 21:23 ` Russell King - ARM Linux
2014-10-15 21:25 ` Russell King - ARM Linux
2014-10-19 9:54 ` Russell King - ARM Linux
2014-10-19 15:28 ` Felipe Balbi
2014-10-19 20:48 ` Olof Johansson
2014-10-09 21:47 ` Aaro Koskinen
2014-10-10 16:18 ` Russell King - ARM Linux
2014-10-10 20:52 ` Aaro Koskinen
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