From owner-freebsd-current@freebsd.org Sun Jul 12 21:46:37 2020 Return-Path: Delivered-To: freebsd-current@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 18D3836FAAE for ; Sun, 12 Jul 2020 21:46:37 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "gate2.funkthat.com", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4B4gMv72mLz45gw for ; Sun, 12 Jul 2020 21:46:35 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (localhost [127.0.0.1]) by gold.funkthat.com (8.15.2/8.15.2) with ESMTPS id 06CLkXOH064306 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Sun, 12 Jul 2020 14:46:33 -0700 (PDT) (envelope-from jmg@gold.funkthat.com) Received: (from jmg@localhost) by gold.funkthat.com (8.15.2/8.15.2/Submit) id 06CLkWFK064305; Sun, 12 Jul 2020 14:46:32 -0700 (PDT) (envelope-from jmg) Date: Sun, 12 Jul 2020 14:46:32 -0700 From: John-Mark Gurney To: bob prohaska Cc: freebsd-current@freebsd.org Subject: Re: Is there any error checking on swap? Message-ID: <20200712214632.GH4213@funkthat.com> Mail-Followup-To: bob prohaska , freebsd-current@freebsd.org References: <20200712033332.GA63411@www.zefox.net> <20200712072911.GG4213@funkthat.com> <20200712153751.GA64898@www.zefox.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200712153751.GA64898@www.zefox.net> X-Operating-System: FreeBSD 11.3-STABLE amd64 X-PGP-Fingerprint: D87A 235F FB71 1F3F 55B7 ED9B D5FF 5A51 C0AC 3D65 X-Files: The truth is out there X-URL: https://www.funkthat.com/ X-Resume: https://www.funkthat.com/~jmg/resume.html X-TipJar: bitcoin:13Qmb6AeTgQecazTWph4XasEsP7nGRbAPE X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? User-Agent: Mutt/1.6.1 (2016-04-27) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (gold.funkthat.com [127.0.0.1]); Sun, 12 Jul 2020 14:46:33 -0700 (PDT) X-Rspamd-Queue-Id: 4B4gMv72mLz45gw X-Spamd-Bar: ++++ Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of jmg@gold.funkthat.com has no SPF policy when checking 208.87.223.18) smtp.mailfrom=jmg@gold.funkthat.com X-Spamd-Result: default: False [4.34 / 15.00]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; NEURAL_SPAM_SHORT(0.62)[0.624]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[funkthat.com]; AUTH_NA(1.00)[]; NEURAL_SPAM_MEDIUM(0.77)[0.769]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; NEURAL_SPAM_LONG(0.75)[0.746]; R_SPF_NA(0.00)[no SPF record]; FORGED_SENDER(0.30)[jmg@funkthat.com,jmg@gold.funkthat.com]; SUBJECT_ENDS_QUESTION(1.00)[]; R_DKIM_NA(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; MIME_TRACE(0.00)[0:+]; FROM_NEQ_ENVFROM(0.00)[jmg@funkthat.com,jmg@gold.funkthat.com]; ASN(0.00)[asn:32354, ipnet:208.87.216.0/21, country:US] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 Jul 2020 21:46:37 -0000 bob prohaska wrote this message on Sun, Jul 12, 2020 at 08:37 -0700: > On Sun, Jul 12, 2020 at 12:29:12AM -0700, John-Mark Gurney wrote: > > bob prohaska wrote this message on Sat, Jul 11, 2020 at 20:33 -0700: > > > Is there any error checking on swap traffic, along the lines of > > > a checksum or parity test? > > > > > > Just curious what happens if a page written out is corrupted when > > > it comes back. > > > > Looks like it doesn't: > > https://svnweb.freebsd.org/base/head/sys/vm/swap_pager.c?annotate=361965#l1389 > > > > Certainly nothing about parity or checksums in the comments. > All faith in the hardware, I guess.... > > Thanks for writing! It probably wouldn't be too hard to add the feature... Just expand the page entry to store a fletcher checksum or the like... Another option would be to try to use swap on ZFS, and use ZFS's builtin checksum feature: https://wiki.freebsd.org/RootOnZFS#ZFS_Swap_Volume -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."