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Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:45446) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kxyNx-0004SJ-2y; Fri, 08 Jan 2021 20:29:25 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1kxyNw-0002SW-4O; Fri, 08 Jan 2021 20:29:24 +0000 Date: Fri, 8 Jan 2021 20:29:24 +0000 From: Russell King - ARM Linux admin To: Linus Torvalds Subject: Re: Aarch64 EXT4FS inode checksum failures - seems to be weak memory ordering issues Message-ID: <20210108202924.GY1551@shell.armlinux.org.uk> References: <20210106172033.GA2165@willie-the-truck> <20210106223223.GM1551@shell.armlinux.org.uk> <20210107111841.GN1551@shell.armlinux.org.uk> <20210107124506.GO1551@shell.armlinux.org.uk> <20210107133747.GP1551@shell.armlinux.org.uk> <20210108092655.GA4031@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210108_152934_155652_EF8D32E3 X-CRM114-Status: GOOD ( 17.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Arnd Bergmann , Theodore Ts'o , Peter Zijlstra , "linux-kernel@vger.kernel.org" , Andreas Dilger , linux-toolchains@vger.kernel.org, Ext4 Developers List , Will Deacon , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jan 08, 2021 at 12:02:53PM -0800, Linus Torvalds wrote: > Well, honestly, I'm always in favor of having people not use ancient > compilers, but both of the issues at hand do seem to be specific to > arm64. > > The "gcc before 5.1 generates incorrect stack pointer writes on arm64" > sounds pretty much deadly, and I think means that yes, for arm64 we > simply need to require 5.1 or newer. > > I also suspect there is much less reason to use old gcc's on arm64. I > can't imagine that people really run very old setups, Is some old RHEL > version even relevant for arm64? For me, six years old for a compiler is really not "very old" - and, when I first encountered this problem, it was over 12 months ago. Apart from the kernel, I am not in the habbit of upgrading stuff for the sake of upgrading - I tend to stick with what I have and what works. Not everyone on this planet has a desire to have the latest and greatest all the time. Since then, I've _not_ wanted to change the compiler in case the problem vanishes without explanation - it had the feeling of being way more serious than a compiler bug, potentially a memory ordering bug. It took about a year just to start being able to work out what was going on - it would take up to about three months to show for me, and when it did, it spat out an ext4 inode checksum error and made the rootfs read-only. To "hide" that by upgrading the compiler, and then to be in the situation where you do not trust any aarch64 machine with your data is no real solution. That's exactly where I was until this had been found. The aarch64 architecture had completely lost my trust as a viable computing platform - and I was at the point of considering disposing of all my aarch64 hardware and replacing it with x86. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel