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Date: Wed, 25 Feb 2015 14:55:34 +0100
From: Denys Vlasenko <dvlasenk@redhat.com>
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To: Andrey Wagin <avagin@gmail.com>
CC: Andy Lutomirski <luto@amacapital.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>, Borislav Petkov <bp@alien8.de>,
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        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"
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On 02/25/2015 01:37 PM, Andrey Wagin wrote:
> 2015-02-13 0:54 GMT+03:00 Denys Vlasenko <dvlasenk@redhat.com>:
> My test vm doesn't boot with this patch. Could you help to investigate
> this issue?

Hi Andrey, thanks for testing!

> I have attached a kernel config and console log.

Looking at the logs, it seems that regular syscalls do work:
systemd managed to function for some time, even spawned
a few children.

It might be that the bug is somewhere in signal delivery code.
This would explain why oops got delayed.


I am trying to reproduce it. My gcc seems to be a bit old -
it can't digest CONFIG_CC_STACKPROTECTOR_STRONG=y in your .config.

I switched to using "only" CONFIG_CC_STACKPROTECTOR_REGULAR=y:

CONFIG_CC_STACKPROTECTOR=y
# CONFIG_CC_STACKPROTECTOR_NONE is not set
CONFIG_CC_STACKPROTECTOR_REGULAR=y
# CONFIG_CC_STACKPROTECTOR_STRONG is not set

and resulting kernel works for me.

Can you send me your bzImage (off-list, of course)?

I'll send you my qemu test setup, can you check whether crash
is happening for you when you run your kernel in it?

-- 
vda