From nobody Sat Mar 02 00:08:08 2024 X-Original-To: questions@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4TmlfZ1PDyz5DJP1 for ; Sat, 2 Mar 2024 00:08:22 +0000 (UTC) (envelope-from kh@panix.com) Received: from mailbackend.panix.com (mailbackend.panix.com [166.84.1.89]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4TmlfY2vd5z4PKr for ; Sat, 2 Mar 2024 00:08:21 +0000 (UTC) (envelope-from kh@panix.com) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=panix.com header.s=panix header.b=nGdJKY7j; dmarc=pass (policy=none) header.from=panix.com; spf=pass (mx1.freebsd.org: domain of kh@panix.com designates 166.84.1.89 as permitted sender) smtp.mailfrom=kh@panix.com Received: from rain.cave (c-73-142-21-0.hsd1.ma.comcast.net [73.142.21.0]) by mailbackend.panix.com (Postfix) with ESMTPSA id 4TmlfP5LJrzyv9 for ; Fri, 1 Mar 2024 19:08:13 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=panix.com; s=panix; t=1709338093; bh=lw4HT2FB/t/o86xzBdYwVWp4gCdISSSFbO71C/SHbIg=; h=Date:From:To:Subject:References:In-Reply-To; b=nGdJKY7jaI8FHbH1/ClN4kJ/9TNLQDLaJuiE0fTcKl6Gl7zKqksfD5WpKd3tBHD2p nqsXsWwfHEdW3H6wzd0OG5TxuXccnLguY4bqdRw56gnkfQ3nXeAjSPGVLJeWq2Hu6p mJ+ptlnb/okHhK9OXEw0qufw20WLaVtjLTxm03cc= Date: Fri, 1 Mar 2024 19:08:08 -0500 From: Kurt Hackenberg To: questions@freebsd.org Subject: Re: FreeBSD 13.2R and OpenZFS bug #15933 Message-ID: References: <27dc6dbd-2ca0-4385-8281-e6bde086bd13@holgerdanske.com> <87eb268e-9429-414a-a3e6-d2e93eaa2119@holgerdanske.com> <5f24be71-67d5-4069-953f-2f86baa54d8d@holgerdanske.com> List-Id: User questions List-Archive: https://lists.freebsd.org/archives/freebsd-questions List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <5f24be71-67d5-4069-953f-2f86baa54d8d@holgerdanske.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.10 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-1.000]; DMARC_POLICY_ALLOW(-0.50)[panix.com,none]; R_SPF_ALLOW(-0.20)[+ip4:166.84.1.64/26]; R_DKIM_ALLOW(-0.20)[panix.com:s=panix]; MIME_GOOD(-0.10)[text/plain]; RWL_MAILSPIKE_GOOD(-0.10)[166.84.1.89:from]; RCVD_VIA_SMTP_AUTH(0.00)[]; ASN(0.00)[asn:2033, ipnet:166.84.0.0/16, country:US]; RCVD_COUNT_ONE(0.00)[1]; RCPT_COUNT_ONE(0.00)[1]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; MLMMJ_DEST(0.00)[questions@freebsd.org]; PREVIOUSLY_DELIVERED(0.00)[questions@freebsd.org]; FROM_HAS_DN(0.00)[]; ARC_NA(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TO_DN_NONE(0.00)[]; DKIM_TRACE(0.00)[panix.com:+] X-Rspamd-Queue-Id: 4TmlfY2vd5z4PKr On Fri, Mar 01, 2024 at 02:04:01PM -0800, David Christensen wrote: >>Here is a write-up of the person that fixed the bug containing all the >>gory details: >>https://despairlabs.com/blog/posts/2023-12-25-openzfs-data-corruption-bug/ ... >I am also reminded of an operating systems course -- specifically: >shared resources, critical sections, and thread-safe programming >techniques. Failing to solve the mutual exclusion problem correctly in >the design is going to result in race conditions in the implementation. >The article discusses concurrent operations, but only implies >concurrent design. I suspect this is where the root cause of the >OpenZFS bugs is to be found. That article sounds like there was no mutual exclusion around the dirty lists. It says the bug they found was fixed, but doesn't say how.