Messages in this thread | | | From | Andrew Lutomirski <> | Date | Wed, 5 Oct 2011 15:46:41 -0700 | Subject | Re: [3.1 patch] x86: default to vsyscall=native |
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On Wed, Oct 5, 2011 at 3:30 PM, Adrian Bunk <bunk@stusta.de> wrote: > On Thu, Oct 06, 2011 at 12:22:34AM +0200, richard -rw- weinberger wrote: >> On Thu, Oct 6, 2011 at 12:13 AM, Andrew Lutomirski <luto@mit.edu> wrote: >> > On Mon, Oct 3, 2011 at 10:33 AM, Adrian Bunk <bunk@stusta.de> wrote: >> >> On Mon, Oct 03, 2011 at 06:04:53AM -0700, Andrew Lutomirski wrote: >> >>> On Mon, Oct 3, 2011 at 2:08 AM, Adrian Bunk <bunk@stusta.de> wrote: >> >>> > After upgrading a kernel the existing userspace should just work >> >>> > (assuming it did work before ;-) ), but when I upgraded my kernel >> >>> > from 3.0.4 to 3.1.0-rc8 a UML instance didn't come up properly. >> >>> > >> >>> > dmesg said: >> >>> > linux-2.6.30.1[3800] vsyscall fault (exploit attempt?) ip:ffffffffff600000 cs:33 sp:7fbfb9c498 ax:ffffffffff600000 si:0 di:606790 >> >>> > linux-2.6.30.1[3856] vsyscall fault (exploit attempt?) ip:ffffffffff600000 cs:33 sp:7fbfb13168 ax:ffffffffff600000 si:0 di:606790 >> >>> > >> >>> > Looking throught the changelog I ended up at commit 3ae36655 >> >>> > ("x86-64: Rework vsyscall emulation and add vsyscall= parameter"). >> >>> > >> >>> > Linus suggested in https://lkml.org/lkml/2011/8/9/376 to default to >> >>> > vsyscall=native. >> >>> > >> >>> > That sounds reasonable to me, and fixes the problem for me. >> >>> >> >>> At this point in the -rc cycle, this sounds fine. >> >>> >> >>> That being said, I'd like to fix it for real for 3.2. This particular >> >>> failure is suspicious -- the "vsyscall fault" message means that >> >>> sys_gettimeofday returned EFAULT, which means that the old (3.0 and >> >>> before) vgettimeofday should *also* have segfaulted. >> >> >> >> This 2.6.30.1 UML kernel binary from 2009 worked for me for all host >> >> kernels from 2.6.30 to 3.0, and with 3.1.0-rc8 and vsyscall=native >> >> it also seems to run nicely. >> >> >> >> Looking deeper into "a UML instance didn't come up properly", >> >> the problem is that it comes up in a strange (readonly) state. >> >> >> >> There are "Using makefile-style concurrent boot in runlevel S." >> >> and "Using makefile-style concurrent boot in runlevel 2." in the >> >> logs with a Debian userspace, but no output from the init scripts >> >> in these broken bootups (normal messages are in non-broken bootups). >> >> >> >> Perhaps the two the messages I see in dmesg on the host are from the >> >> processes running rcS and rc2 failing early? >> >> >> >> In a working startup with a Debian userspace, I'm getting during rcS >> >> Setting the system clock. >> >> Cannot access the Hardware Clock via any known method. >> >> Use the --debug option to see the details of our search for an access method. >> >> Unable to set System Clock to: Mon Oct 3 17:01:35 UTC 2011 ... (warning). >> >> >> >>> We do have a bit >> >>> of a bug in that the new code doesn't report si_addr properly, but >> >>> that sounds unlikely as a culprit. Did you try with the offending >> >>> commit reverted (i.e. fce8dc0)? I bet that it also fails there. >> >> >> >> fce8dc0 is "x86-64: Wire up getcpu syscall", is that really the one you >> >> want me to revert? >> >> >> >>> What's the .config for your UML binary? I'd like to see if I can >> >>> reproduce this. >> >> >> >> It's attached. >> >> >> > >> > I can't reproduce it. What distro is running inside the UML instance? >> >> Same here. >> Adrian, is the UML kernel crashing before executing init? > > As I wrote: > Looking deeper into "a UML instance didn't come up properly", > the problem is that it comes up in a strange (readonly) state. > > The UML kernel is running happily without crashing, and as I wrote my > guess about my problems is: > Perhaps the two the messages I see in dmesg on the host are from the > processes running rcS and rc2 failing early? > >> We definitely need more information... > > I gave the information that was requested. plus my observations. > > What more information exactly do you need from me?
None :) I just reproduced the problem with Debian Squeeze. Lenny works fine.
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