From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: xenstored crashes with SIGSEGV Date: Tue, 16 Dec 2014 11:06:10 +0000 Message-ID: <1418727970.16425.217.camel@citrix.com> References: <546461A2.2070908@univention.de> <1415869951.31613.26.camel@citrix.com> <548B1472.5080302@univention.de> <1418401932.16425.34.camel@citrix.com> <548B1BA8.3090504@univention.de> <1418403387.16425.38.camel@citrix.com> <548B23FA.6070108@univention.de> <1418407116.16425.53.camel@citrix.com> <1418649458.16425.108.camel@citrix.com> <548EEDF5.20808@univention.de> <1418655014.16425.138.camel@citrix.com> <1418665524.16425.171.camel@citrix.com> <548F60BF.4020901@univention.de> <1418726712.16425.213.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1418726712.16425.213.camel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Philipp Hahn Cc: Ian Jackson , Xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On Tue, 2014-12-16 at 10:45 +0000, Ian Campbell wrote: > On Mon, 2014-12-15 at 23:29 +0100, Philipp Hahn wrote: > > > I notice in your bugzilla (for a different occurrence, I think): > > >> [2090451.721705] univention-conf[2512]: segfault at ff00000000 ip 000000000045e238 sp 00007ffff68dfa30 error 6 in python2.6[400000+21e000] > > > > > > Which appears to have faulted access 0xff000000000 too. It looks like > > > this process is a python thing, it's nothing to do with xenstored I > > > assume? > > > > Yes, that's one univention-config, which is completely independent of > > xen(stored). > > > > > It seems rather coincidental that it should be accessing the > > > same sort of address and be faulting. > > > > Yes, good catch. I'll have another look at those core dumps. > > With this in mind, please can you confirm what model of machines you've > seen this on, and in particular whether they are all the same class of > machine or whether they are significantly different. > > The reason being that randomly placed 0xff values in a field of 0x00 > could possibly indicate hardware (e.g. a GPU) DMAing over the wrong > memory pages. Thanks for giving me access to the core files. This is very suspicious: (gdb) frame 2 #2 0x000000000040a348 in tdb_open_ex (name=0x1941fb0 "/var/lib/xenstored/tdb.0x1935bb0", hash_size=, tdb_flags=0, open_flags=, mode=, log_fn=0x4093b0 , hash_fn=) at tdb.c:1958 1958 SAFE_FREE(tdb->locked); (gdb) x/96x tdb 0x1921270: 0x00000000 0x00000000 0x00000000 0x00000000 0x1921280: 0x0000001f 0x000000ff 0x0000ff00 0x000000ff 0x1921290: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x19212a0: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x19212b0: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x19212c0: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x19212d0: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x19212e0: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x19212f0: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x1921300: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x1921310: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x1921320: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x1921330: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x1921340: 0x00000000 0x00000000 0x0000ff00 0x000000ff 0x1921350: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x1921360: 0x00000000 0x000000ff 0x0000ff00 0x000000ff 0x1921370: 0x004093b0 0x00000000 0x004092f0 0x00000000 0x1921380: 0x00000002 0x00000000 0x00000091 0x00000000 0x1921390: 0x0193de70 0x00000000 0x01963600 0x00000000 0x19213a0: 0x00000000 0x00000000 0x0193fbb0 0x00000000 0x19213b0: 0x00000000 0x00000000 0x00000000 0x00000000 0x19213c0: 0x00405870 0x00000000 0x0040e3e0 0x00000000 0x19213d0: 0x00000038 0x00000000 0xe814ec70 0x6f2f6567 0x19213e0: 0x01963650 0x00000000 0x0193dec0 0x00000000 Something has clearly done a number on the ram of this process. 0x1921270 through 0x192136f is 256 bytes... Since it appears to be happening to other processes too I would hazard that this is not a xenstored issue. Ian.