From: Denys Vlasenko <dvlasenk@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>,
Stefan Seyfried <stefan.seyfried@googlemail.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Takashi Iwai <tiwai@suse.de>, X86 ML <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>, Tejun Heo <tj@kernel.org>
Subject: Re: PANIC: double fault, error_code: 0x0 in 4.0.0-rc3-2, kvm related?
Date: Wed, 18 Mar 2015 21:06:20 +0100 [thread overview]
Message-ID: <5509DABC.7040401@redhat.com> (raw)
In-Reply-To: <CALCETrU2R020HVniX2sczxexPO2qhEPbS++9DXzcxeycgxoGQg@mail.gmail.com>
On 03/18/2015 08:26 PM, Andy Lutomirski wrote:
> Hi Linus-
>
> You seem to enjoy debugging these things. Want to give this a shot?
> My guess is a vmalloc fault accessing either old_rsp or kernel_stack
> right after swapgs in syscall entry.
The code is:
ENTRY(system_call)
SWAPGS_UNSAFE_STACK
GLOBAL(system_call_after_swapgs)
movq %rsp,PER_CPU_VAR(rsp_scratch)
movq PER_CPU_VAR(kernel_stack),%rsp
If PER_CPU_VAR(var) memory access can page fault
(I was thinking this is ensured to never fault),
then on these two instructions such page fault
will be fatal: we will still have userspace %rsp.
I thought we can only get a NMI or debug interrupt here,
and they are both set up to use IST stacks
to prevent this scenario (among other reasons).
--
vda
next prev parent reply other threads:[~2015-03-18 20:06 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-15 8:17 PANIC: double fault, error_code: 0x0 in 4.0.0-rc3-2, kvm related? Stefan Seyfried
2015-03-18 14:16 ` Takashi Iwai
2015-03-18 15:05 ` Takashi Iwai
2015-03-18 17:43 ` Takashi Iwai
2015-03-18 17:46 ` Takashi Iwai
2015-03-18 18:03 ` Andy Lutomirski
2015-03-18 19:03 ` Stefan Seyfried
2015-03-18 19:26 ` Andy Lutomirski
2015-03-18 20:05 ` Stefan Seyfried
2015-03-18 20:51 ` Andy Lutomirski
2015-03-18 21:12 ` Stefan Seyfried
2015-03-18 21:21 ` Andy Lutomirski
2015-03-18 21:41 ` Stefan Seyfried
2015-03-18 21:49 ` Denys Vlasenko
2015-03-18 21:53 ` Stefan Seyfried
2015-03-18 20:06 ` Denys Vlasenko [this message]
2015-03-18 20:49 ` Andy Lutomirski
2015-03-18 21:06 ` Denys Vlasenko
2015-03-18 21:17 ` Andy Lutomirski
2015-03-18 21:32 ` Linus Torvalds
2015-03-18 21:42 ` Denys Vlasenko
2015-03-18 21:55 ` Andy Lutomirski
2015-03-18 22:17 ` Denys Vlasenko
2015-03-18 22:20 ` Andy Lutomirski
2015-03-18 22:27 ` Denys Vlasenko
2015-03-18 22:18 ` Linus Torvalds
2015-03-18 22:24 ` Andy Lutomirski
2015-03-18 22:22 ` Jiri Kosina
2015-03-18 22:28 ` Linus Torvalds
2015-03-18 22:29 ` Andy Lutomirski
2015-03-18 22:29 ` Andy Lutomirski
2015-03-18 22:38 ` Stefan Seyfried
2015-03-18 22:40 ` Andy Lutomirski
2015-03-18 23:22 ` Andy Lutomirski
2015-03-19 0:23 ` Stefan Seyfried
2015-03-19 0:57 ` Andy Lutomirski
2015-03-19 2:15 ` Linus Torvalds
2015-03-19 6:24 ` Stefan Seyfried
2015-03-19 10:16 ` Takashi Iwai
2015-03-19 10:58 ` Denys Vlasenko
2015-03-19 11:21 ` Takashi Iwai
2015-03-19 12:48 ` Denys Vlasenko
2015-03-19 13:47 ` Takashi Iwai
2015-03-19 14:55 ` Takashi Iwai
2015-03-19 15:22 ` Takashi Iwai
2015-03-19 15:41 ` Andy Lutomirski
2015-03-19 15:51 ` Takashi Iwai
2015-03-19 16:01 ` Andy Lutomirski
2015-03-20 18:16 ` Denys Vlasenko
2015-03-20 18:50 ` Takashi Iwai
2015-03-23 9:02 ` Takashi Iwai
2015-03-23 9:35 ` Takashi Iwai
2015-03-23 13:22 ` Takashi Iwai
2015-03-23 16:07 ` Denys Vlasenko
2015-03-23 17:18 ` Takashi Iwai
2015-03-23 17:46 ` Denys Vlasenko
2015-03-23 18:43 ` Takashi Iwai
2015-03-23 18:38 ` Andy Lutomirski
2015-03-23 18:48 ` Andy Lutomirski
2015-03-23 18:59 ` Takashi Iwai
2015-03-23 19:10 ` [PATCH] x86, entry: Check for syscall exit work with IRQs disabled Andy Lutomirski
2015-03-23 19:21 ` Denys Vlasenko
2015-03-23 19:27 ` Andy Lutomirski
2015-03-23 19:32 ` Andy Lutomirski
2015-03-24 11:17 ` Takashi Iwai
2015-03-24 20:08 ` Ingo Molnar
2015-03-25 0:35 ` Andy Lutomirski
2015-03-25 12:21 ` Ingo Molnar
2015-03-25 15:07 ` Andy Lutomirski
2015-03-25 9:13 ` [tip:x86/asm] x86/asm/entry: " tip-bot for Andy Lutomirski
2015-03-23 18:54 ` PANIC: double fault, error_code: 0x0 in 4.0.0-rc3-2, kvm related? Stefan Seyfried
2015-03-23 18:56 ` Takashi Iwai
2015-03-23 19:07 ` Denys Vlasenko
2015-03-23 19:10 ` Andy Lutomirski
2015-03-19 13:21 ` Denys Vlasenko
2015-03-18 21:49 ` Stefan Seyfried
2015-03-28 23:57 ` Maciej W. Rozycki
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