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[174.88.78.8]) by smtp.gmail.com with ESMTPSA id o21-v6sm36072151pfa.54.2018.09.19.14.20.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Sep 2018 14:20:37 -0700 (PDT) Sender: Mark Johnston Date: Wed, 19 Sep 2018 17:20:34 -0400 From: Mark Johnston To: Steve Kargl Cc: freebsd-current@freebsd.org Subject: Re: ALPHA4 panic in VM Message-ID: <20180919212034.GD99168@raichu> References: <20180919200152.GA1164@troutmask.apl.washington.edu> <20180919210211.GC99168@raichu> <20180919211156.GA1677@troutmask.apl.washington.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180919211156.GA1677@troutmask.apl.washington.edu> User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.27 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: Wed, 19 Sep 2018 21:20:40 -0000 On Wed, Sep 19, 2018 at 02:11:56PM -0700, Steve Kargl wrote: > On Wed, Sep 19, 2018 at 05:02:11PM -0400, Mark Johnston wrote: > > On Wed, Sep 19, 2018 at 01:01:52PM -0700, Steve Kargl wrote: > > > I have the kernel and core file if more information is needed. > > > > > > % cat info.2 > > > Dump header from device: /dev/ada0p3 > > Architecture: amd64 > > > Architecture Version: 2 > > > Dump Length: 2348281856 > > > Blocksize: 512 > > > Compression: none > > > Dumptime: Wed Sep 19 12:29:59 2018 > > > Hostname: troutmask.apl.washington.edu > > > Magic: FreeBSD Kernel Dump > > > Version String: FreeBSD 12.0-ALPHA4 #0 r338505: Thu Sep 6 13:45:34 PDT 2018 > > > kargl@troutmask.apl.washington.edu:/usr/obj/usr/src/amd64.amd64/sys/SPEW > > > Panic String: page fault > > > Dump Parity: 2676008548 > > > Bounds: 2 > > > Dump Status: good > > > > > > % more core.txt.2 > > > Fatal trap 12: page fault while in kernel mode > > > cpuid = 1; apic id = 11 > > > fault virtual address = 0xffffb8000719a428 > > > > This seems to be the result of a bit-flip. cred is 0xffffb8000719a400, > > which is almost but not quite in the direct map. In particular we have: > > > > (kgdb) frame 10 > > #10 0xffffffff8083e07d in vm_object_destroy (object=) at /usr/src/sys/vm/vm_object.c:703 > > 703 swap_release_by_cred(object->charge, object->cred); > > (kgdb) p object > > $8 = > > (kgdb) p *(vm_object_t)$r13 > > $9 = { > > ... > > cred = 0xffffb8000719a400, > > charge = 28672, > > umtx_data = 0x0 > > } > > (kgdb) p *(struct ucred *)0xfffff8000719a400 > > $10 = { > > cr_ref = 5737, > > cr_uid = 1001, > > cr_ruid = 1001, > > cr_svuid = 1001, > > cr_ngroups = 7, > > cr_rgid = 1001, > > cr_svgid = 1001, > > cr_uidinfo = 0xfffff80007285500, > > cr_ruidinfo = 0xfffff80007285500, > > cr_prison = 0xffffffff80a9de10 , > > ... > > > > That is, flipping one of the bits in the fault address leads me to a > > valid ucred. This could in principle be the result of a software bug, > > but I'd be more inclined to suspect the hardware. > > Mark, > > Thanks for looking into the problem. This system has > been running for probably 2 years or so without issues. > I guess it's time to pull out memtest86+ (or similar) > to see if hardware is starting to fail. I'm not sure whether you're using ECC RAM, but if not, the system is susceptible to silent random bit flips.