Messages in this thread | | | Subject | Re: kmemcheck in linux-next causes NULL pointer dereference at task_rq_lock | From | Eric Paris <> | Date | Fri, 21 Aug 2009 14:04:35 -0400 |
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On Fri, 2009-08-21 at 19:20 +0200, Vegard Nossum wrote: > 2009/8/10 Eric Paris <eparis@redhat.com>: > > On Mon, 2009-08-10 at 20:56 +0200, Vegard Nossum wrote: > >> 2009/8/10 Eric Paris <eparis@redhat.com>: > >> > I'm using 2.6.31-rc5-next-20090810 on a vmware server. Originally I saw > >> > messages about setting to one cpu, so I booted with maxcpu=1. I get > >> > this same panic with and without maxpu. Booting with kmemcheck=0 boots > >> > just fine. > >> > > >> > I have not tested kmemcheck in linus' tree but will start looking for a > >> > working version now. Any suggestions or things I should try? > >> > >> Hi, thanks for the report, and for trying it out. > >> > >> Does it crash with "kmemcheck=0 maxcpus=1" (it should be maxcpus, not > >> maxcpu). This should be a simple way of determining whether it was > >> kmemcheck or the existing maxcpus code, which we use, that broke. > > > > I boots fine with kmemcheck=0 > > > > I did get the command line right. maxcpus=1 kmemcheck=1 was the panic I > > showed in the last message. > > > >> If you can send config (off-list, probably), I will try to reproduce > >> and investigate more tomorrow. > > > > Will send it now. > > Thanks. I've tried your config with next-20090810, next-20090820, and > current mainline, and wasn't able to reproduce it anywhere :-/ > > Does it still occur for you with the most recent linux-next or current mainline? > > In any case, I think the kmemcheck SMP-handling code has to be fixed. > It seems that we currently allow CPU hotplug while kmemcheck is > enabled, which could lead to, erm, interesting crashes. Maybe we could > do something like what mmiotrace does.
I just tried it again with 0821. The machine doesn't boot with kmemcheck=1 but it doesn't look like it's directly kmemcheck's fault. I poked others about their problems. I'm going to be giving it a shot on a different box.
-Eric
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