From owner-svn-src-all@freebsd.org Tue Jul 21 01:41:59 2015 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 4595E9A7410; Tue, 21 Jul 2015 01:41:59 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from bigwig.baldwin.cx (bigwig.baldwin.cx [IPv6:2001:470:1f11:75::1]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 21B209AC; Tue, 21 Jul 2015 01:41:59 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from ralph.baldwin.cx (75-48-78-19.lightspeed.cncrca.sbcglobal.net [75.48.78.19]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 2E376B94F; Mon, 20 Jul 2015 21:41:58 -0400 (EDT) From: John Baldwin To: Alan Cox Cc: Adrian Chadd , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r285387 - in head: lib/libc/sys share/man/man4 sys/conf sys/kern sys/sys sys/vm usr.bin usr.bin/numactl Date: Mon, 20 Jul 2015 10:47:58 -0700 Message-ID: <14982298.P5Y2Xh6Asn@ralph.baldwin.cx> User-Agent: KMail/4.14.3 (FreeBSD/10.1-STABLE; KDE/4.14.3; amd64; ; ) In-Reply-To: <55A1445F.50901@rice.edu> References: <201507111521.t6BFLcrv039934@repo.freebsd.org> <55A1445F.50901@rice.edu> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Mon, 20 Jul 2015 21:41:58 -0400 (EDT) X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Jul 2015 01:41:59 -0000 On Saturday, July 11, 2015 11:29:19 AM Alan Cox wrote: > On 07/11/2015 10:21, Adrian Chadd wrote: > > * The VM doesn't handle unbalanced domains very well, and if you have an overly > > unbalanced memory setup whilst under high memory pressure, VM page allocation > > may fail leading to a kernel panic. This was a problem in the past, but it's > > much more easily triggered now with these tools. > > > > > For the record, no, it doesn't panic. Both the first-touch scheme in > 9.x and the round-robin scheme in 10.x fall back to allocating from a > different domain until some page is found. I got a panic (don't recall exactly which) with the 9.x version once (albeit with that version backported to 8.x) where vm_page_alloc() returned NULL when a caller did not expect it based on the global paging targets. Unfortunately I no longer have access to the core (or any notes I might have had from debugging it). I don't recall why it didn't fall back to using a page from another domain (especially since the 9.x version just prefers local, doesn't require local). Note that I only saw this once across hundreds of machines running the 9.x version in production for 5 years or so. -- John Baldwin