Re: [PATCH 2/3 v3] x86: entry_64.S: always allocate complete "struct pt_regs"

From: Stephen Rothwell <sfr@canb.auug.org.au>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>,
	Sabrina Dubroca <sd@queasysnail.net>,
	Andy Lutomirski <luto@amacapital.net>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	Andrey Wagin <avagin@gmail.com>, Ingo Molnar <mingo@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Frederic Weisbecker <fweisbec@gmail.com>, X86 ML <x86@kernel.org>,
	Alexei Starovoitov <ast@plumgrid.com>,
	Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/3 v3] x86: entry_64.S: always allocate complete "struct pt_regs"
Date: Thu, 26 Feb 2015 17:25:47 +1100	[thread overview]
Message-ID: <20150226172547.565a6729@canb.auug.org.au> (raw)
In-Reply-To: <20150225211852.428143fb78e921fd6e4d4e9e@linux-foundation.org>

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Hi all,

On Wed, 25 Feb 2015 21:18:52 -0800 Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Thu, 26 Feb 2015 02:12:57 +0100 Denys Vlasenko <vda.linux@googlemail.com> wrote:
> 
> > On Thu, Feb 26, 2015 at 12:34 AM, Sabrina Dubroca <sd@queasysnail.net> wrote:
> > > 2015-02-25, 23:40:55 +0100, Sabrina Dubroca wrote:
> > >> I can run some userspace programs, but I have no idea what would be
> > >> helpful.
> > >> I can also try booting a real machine with archlinux/systemd tomorrow.
> > >
> > > I got a good boot out of kernels that normally fail.  I booted
> > > systemd's emergency shell and enabled a few services, in the same
> > > order they normally start.  journald started cleanly, but after that,
> > > every single command produced a "traps:" output and an "audit:" line.
> > >
> > > I disabled systemd-journald (chmod -x, because `systemctl disable`
> > > didn't really disable it), and now it boots, no "traps:" in the log.
> > > If I run it, everything fails again (zsh has traps for simply pressing
> > > enter on an empty cmd).
> > 
> > That's some progress!
> > 
> > It's strange how one process manages to affect everything else.
> > 
> > "If I run it, everything fails again". How do you run it? Directly,
> > or via systemd services mechanism?
> > If you just run it directly, can you try running it under
> > "strace -f -tt -oLOG"? Does it have the same effect? What's in the LOG?
> 
> I'm hitting this bug as well, bisected to this commit.  On an old
> x64_64 box, no vms, paravirt, etc.  Running FC6 userspace (heh).
> 
> Quite late in initscripts, binaries start getting segmentation faults
> and init gives up.  Seems to only affect /usr/bin/rhgb-client.  There's
> one instance where /bin/rm is said to segfault, but I suspect that's
> init lying to me.

I note that that commit has been removed from today's version of the
luto-misc tree and thus linux-next.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au

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