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From: Marco Elver <elver@google.com>
To: Qian Cai <cai@lca.pw>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	"paul E. McKenney" <paulmck@kernel.org>,
	kasan-dev <kasan-dev@googlegroups.com>,
	LKML <linux-kernel@vger.kernel.org>,
	kvm@vger.kernel.org
Subject: Re: KCSAN + KVM = host reset
Date: Fri, 10 Apr 2020 13:35:30 +0200	[thread overview]
Message-ID: <CANpmjNPqQHKUjqAzcFym5G8kHX0mjProOpGu8e4rBmuGRykAUg@mail.gmail.com> (raw)
In-Reply-To: <AC8A5393-B817-4868-AA85-B3019A1086F9@lca.pw>

On Fri, 10 Apr 2020 at 13:25, Qian Cai <cai@lca.pw> wrote:
>
>
>
> > On Apr 10, 2020, at 5:47 AM, Marco Elver <elver@google.com> wrote:
> >
> > That would contradict what you said about it working if KCSAN is
> > "off". What kernel are you attempting to use in the VM?

Ah, sorry this was a typo,
  s/working if KCSAN/not working if KCSAN/

> Well, I said set KCSAN debugfs to “off” did not help, i.e., it will reset the host running kvm.sh. It is the vanilla ubuntu 18.04 kernel in VM.
>
> github.com/cailca/linux-mm/blob/master/kvm.sh

So, if you say that CONFIG_KCSAN_INTERRUPT_WATCHER=n works, that
contradicts it not working when KCSAN is "off". Because if KCSAN is
off, it never sets up any watchpoints, and whether or not
KCSAN_INTERRUPT_WATCHER is selected or not shouldn't matter. Does that
make more sense?

But from what you say, it's not the type of kernel run in VM. I just
thought there may be some strange interaction if you also run a KCSAN
kernel inside the VM.

Since I have no way to help debug right now, if you say that
"KCSAN_SANITIZE_svm.o := n" works, I'd suggest that you just send a
patch for that. If you think that's not adequate, it may be possible
to try and find the offending function(s) in that file and add
__no_kcsan to the  function(s) that cause problems.

Thanks,
-- Marco

  reply	other threads:[~2020-04-10 11:35 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-08 20:59 KCSAN + KVM = host reset Qian Cai
2020-04-08 21:25 ` Paolo Bonzini
2020-04-08 21:29   ` Qian Cai
2020-04-09  7:03     ` Marco Elver
2020-04-09 15:10       ` Qian Cai
2020-04-09 15:22         ` Marco Elver
2020-04-09 15:30           ` Qian Cai
2020-04-09 16:03             ` Marco Elver
2020-04-09 21:28               ` Qian Cai
2020-04-09 23:00                 ` Qian Cai
2020-04-10  9:47                   ` Marco Elver
2020-04-10 11:25                     ` Qian Cai
2020-04-10 11:35                       ` Marco Elver [this message]
2020-04-10 15:50                         ` Qian Cai
2020-04-10 16:04                           ` Paolo Bonzini
2020-04-10 16:06                           ` Sean Christopherson
2020-04-10 19:57                         ` Qian Cai
2020-04-13  8:35                           ` Marco Elver

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