Re: [PATCH] Gerd Hoffman's move-vsyscall-into-user-address-range patch

[Andrew Morton <akpm@osdl.org>]

Ingo Molnar <mingo@elte.hu> wrote:
>
> 
> * Andrew Morton <akpm@osdl.org> wrote:
> 
> > Rusty Russell <rusty@rustcorp.com.au> wrote:
> > >
> > > Name: Move vsyscall page out of fixmap into normal vma as per mmap
> > 
> > This causes mysterious hangs when starting init.
> > 
> > Distro is RH FC1, running SysVinit-2.85-5.
> > 
> > dmesg, sysrq-T and .config are at
> > http://www.zip.com.au/~akpm/linux/patches/stuff/log-vmm - nothing leaps
> > out.
> > 
> > This is the second time recently when a patch has caused this machine 
> > to oddly hang in init.  It's possible that there's a bug of some form 
> > in that version of init that we'll need to know about and take care of 
> > in some fashion.
> 
> FC1 is like really ancient. I think there was a glibc bug that caused 
> vsyscall related init hangs like that. To nevertheless let people run 
> their old stuff there's a vdso=0 boot option in exec-shield.
> 

Well that patch took a machine from working to non-working.  Pretty serious
stuff.  We should get to the bottom of the problem so we can assess the
risk and impact, no?