On 11/23/2017 10:03 PM, Dave Anderson wrote: >> Hi Dave, >> Â Because I didn't subscribe the list, so please CC me when reply:) My >> colleague help to forward your reply to me, so I decide to reply >> directly in order to keep this mail in the thread other than new a thread. >> >> On 11/23/2017 02:04 PM, Fei, Jie/è´¹ æ° wrote: >>> >>> >>> >>> -------- Forwarded Message -------- >>> Subject: Re: crash: page excluded: kernel virtual >>> address: ffffffff81e3da50 type: "page_offset_base" >>> Date: Wed, 22 Nov 2017 09:35:40 -0500 >>> From: Dave Anderson <anderson@xxxxxxxxxx> >>> Reply-To: Discussion list for crash utility usage, maintenance and >>> development <crash-utility@xxxxxxxxxx> >>> To: Discussion list for crash utility usage, maintenance and >>> development <crash-utility@xxxxxxxxxx> >>> >>> >>> >>> ----- Original Message ----- >>>> Hi, >>>> >>>> I am using the latest crash tool & kernel 4.14 compiled from source, >>>> and >>>> I got the following error message. As I searched, this is fixed in >>>> crash >>>> 7.2.0, but I still have it here. So, is anyone has a clue? >>> >>> It's always going to be a crap-shoot with very recent upstream kernels, >>> but you haven't given enough information to determine what the issue is. >>> >> >> Sorry, I am to new dump/crash area. >> >>> If the vmcore was created by "virsh dump", and the kernel has KASLR >>> enabled, >>> then it's just not supported at this time. Otherwise, perhaps the >>> output of >>> "crash -d8" may yield some clues. >>> >> >> I am using kdump to create the vmcore. Actually, I did solve this issue >> by add "nokaslr" to kernel parameter when I used the built-in crash of >> Fedora. But when turn to the compiled version of my own, that solution >> don't work. here is the output of `crash -d8`: >> [snip] > > OK, so you seem to be describing two issues: > > (1) With KASLR enabled, the vmcore cannot be read by either > Fedora's 7.2.0-1 or upstream 7.2.0++. > (2) With KASLR disabled, the vmcore can be read by Fedora's > 7.2.0-1, but cannot be read by 7.2.0++, > Yes, you give a good summary, but it is Fedora 26's 7.1.9.1(I did the test in Fedora 26-4.13.10-200.fc26.x86_64 a weeks ago, now upgrade to 27, and the fedora crash version now is 7.1.9.3), not 7.2.0-1. Now I have upgraded to Fedora 27, I have 2 kernels: 1. fedora kernel is 4.13.13-300.fc27.x86_64 2. kernel 4.14.0 compiled from source. and 2 crash tool: 1. Fedora's 7.1.9.3 2. 7.2.0++ compiled from source > When you run crash on the live system, what happens when: > > (1) KASLR is enabled, running Fedora's 7.2.0-1 > (2) KASLR is enabled, running upstream 7.2.0++ > (2) KASLR is disabled, running Fedora's 7.2.0-1 > (3) KASLR is disabled, running upstream 7.2.0++ > > I don't see anything unusual in the output above, presuming the > the phys_base of 0 is correct. When you run crash on the live > system, what is the output of "help -m | grep phys_base"> During my test recent days, I find some new interesting things: sometimes the vmcore file is exceptional small, like about 500k, while in normal condition, it is about 2G(machine has 4G memory). I confirmed the following facts with tests: 1. kernel 4.14.0: without nokaslr, vmcore's size looks ok, about 2G 2. kernel 4.14.0: with nokaslr, vmcore's size looks wrong, about 500k So I am not sure some of my previous tests are reliable. I will do a new round test, and capture the -d8 out in both condition(live system & dump file) BTW, I think the fedora version crash tool should works well with fedora kernel? But in my test, crash 7.1.9.3 & 4.13.13-300.fc27.x86_64, crash report: crash: cannot resolve "init_level4_pgt" which is said is solved in crash 7.2.0 > I need to compare the crash -d8 output above with the same > crash -d8 output from the working session using the same > KASLR disabled vmcore, showing at least up until the point that > it does the readmem of "page_offset_base" above? > > Also, if you can make the 2 vmcores available, please send me > the details of how to download them in a private email to > anderson@xxxxxxxxxx or anderson@xxxxxxxxxxxx. If you have > modified/rebuilt the Fedora kernel, I would also need a copy > of the vmlinux file as well. > Thanks very much, Dave, I will give you feedback after I have done the new round test. If you have any suggestion for test, also please tell me:) -- Sincerely, Cao jin -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
