Date: Thu, 23 Apr 2015 23:00:17 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Scott Long <scott4long@yahoo.com> Cc: Chagin Dmitry <dchagin@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r281451 - head/sys/vm Message-ID: <CAJ-VmonQdnkLEhspj120bPMGO9PbVJv7vkNVVt%2B42viSNwL1Ww@mail.gmail.com> In-Reply-To: <FFE5F8D2-A15E-4087-93F5-3640662217DD@yahoo.com> References: <201504120621.t3C6LxAV095209@svn.freebsd.org> <5B48434B-EA97-45B3-BC4E-B039A868186B@yahoo.com> <4E109480-FD27-4C7F-8B5F-B1DB2232CD3D@yahoo.com> <20150423192819.GA13122@dchagin.static.corbina.net> <FFE5F8D2-A15E-4087-93F5-3640662217DD@yahoo.com>
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On 23 April 2015 at 22:26, Scott Long <scott4long@yahoo.com> wrote: > >> On Apr 23, 2015, at 1:28 PM, Chagin Dmitry <dchagin@freebsd.org> wrote: >> >> On Thu, Apr 23, 2015 at 12:49:51PM -0600, Scott Long wrote: >>> >>>> On Apr 23, 2015, at 6:19 AM, Scott Long <scott4long@yahoo.com> wrote: >>>> >>>>> >>>>> On Apr 12, 2015, at 12:21 AM, Dmitry Chagin <dchagin@FreeBSD.org> wro= te: >>>>> >>>>> Author: dchagin >>>>> Date: Sun Apr 12 06:21:58 2015 >>>>> New Revision: 281451 >>>>> URL: https://svnweb.freebsd.org/changeset/base/281451 >>>>> >>>>> Log: >>>>> Rework r281162. Indeed, the flexible array member is preferable here. >>>>> >>>>> Suggested by: Justin T. Gibbs >>>>> >>>>> MFC after: 3 days >>>>> >>>>> Modified: >>>>> head/sys/vm/uma_core.c >>>>> head/sys/vm/uma_int.h >>>> >>>> There???s still something wrong with this. I have a machine with 28 c= ores (56 with hyperthreading) and 256GB of RAM, and ever since you committe= d r281162, it panics early in boot with a failed assertion. It looks like = the first few members of a uma_slab_t are getting overwritten accidentally,= and somehow the padding of the extra member in the uma_zone_t was previous= ly protecting it. I don???t know the exact cause yet, but I must ask that = you revert to r281161 in HEAD and stable/10 until the problem is resolved. >>>> >>> >>> I think the problem is that the masterzone_k and masterzone_z objects t= hat are statically allocated in uma_core.c no longer have space for the uz_= cpu field, but uma_zalloc_arg() always assumes that it???s there. Early in= boot when the ???kegs' and ???zones??? zones are being initialized, there?= ??s only 1 CPU so pre-allocating 1 uz_cpu element in the uma_zone is enough= . I can???t see any way around this without significantly changing how uma= _zalloc_arg() treats per-cpu caches. I think it???s best to revert this ch= ange. >>> >> Hi, >> they initialized in uma_startup() and not used before. >> I have a private converstion with a man which stable/10 hangs in vm_mem_= init().\ >> with my commit. weird. >> >> I do not object to revert, but give me a chance to figure out what's goi= ng on. > > With INVARIANTS enabled, the system will panic. Without it, it will spin= in vm_mem_init(), as you noted. Even if it=E2=80=99s not happening to eve= ryone, it=E2=80=99s a serious problem for such a minor anticipated benefit.= I must insist that it be reverted. Hi, +1 - please revert the patch for now and figure it out locally. Having -HEAD broken is very annoying. -a
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