From: Paolo Bonzini <pbonzini@redhat.com>
To: speck@linutronix.de
Subject: [MODERATED] Re: [PATCH v5 8/8] NX 8
Date: Thu, 10 Oct 2019 19:37:26 +0200 [thread overview]
Message-ID: <b64a39a1-3842-467f-2fb1-7879b23451f7@redhat.com> (raw)
In-Reply-To: <35501bba-c087-8e86-363b-e21ec6a6ced1@redhat.com>
[-- Attachment #1: Type: text/plain, Size: 1559 bytes --]
On 10/10/19 18:50, Paolo Bonzini wrote:
> On 10/10/19 18:14, Paolo Bonzini wrote:
>> On 10/10/19 07:53, speck for Pawan Gupta wrote:
>>> We can help debug the crash. Can you please share the series,
>>> reproduction steps and the crash signature.
>
> The bug is a race condition between kvm_mmu_zap_all and, well,
> everything else. It is triggered when nx_huge_pages is clear/set while
> the recovery thread runs.
Gah, figured it out. It's specific to v6. I'll post the fixed patches
tomorrow, dinnertime now.
Paolo
> Paolo
>
>> The reproduction steps for v5 are as follows:
>>
>> - grab the next branch of kvm-unit-tests.git[1] and build it
>>
>> - create a lot of hugepages, on my machine I use 40 GiB worth of them:
>>
>> echo 20480 > /proc/sys/vm/nr_hugepages
>>
>> - load KVM with kvm.nx_huge_pages_recovery_period_secs=3
>>
>> - run the following script
>>
>> while true; do
>> echo N > /sys/module/kvm/parameters/nx_huge_pages; sleep 1
>> echo Y > /sys/module/kvm/parameters/nx_huge_pages; sleep 5
>> done
>>
>> - run the testcase with
>>
>> MEM=40960 # in megabytes
>> qemu-kvm -nodefaults -vnc none -serial stdio -kernel x86/hugetext.flat
>> -m $MEM -mem-path /dev/hugepages
>>
>> You can also add a WARN_ON_ONCE(!sp->lpage_disallowed) to
>> kvm_recover_nx_lpages before the call to kvm_mmu_prepare_zap_page. As
>> soon as it triggers, of course everything will go downhill.
>>
>> Paolo
>>
>> [1] git://git.kernel.org/pub/scm/virt/kvm/kvm-unit-tests.git
>>
>
>
next prev parent reply other threads:[~2019-10-10 17:37 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1561989149-17323-1-git-send-email-pbonzini@redhat.com>
[not found] ` <1561989149-17323-9-git-send-email-pbonzini@redhat.com>
[not found] ` <8eab605b-df0e-74d0-e448-986149edf33e@redhat.com>
2019-10-02 20:38 ` [MODERATED] Re: [PATCH v5 8/8] NX 8 Pawan Gupta
2019-10-02 20:59 ` Paolo Bonzini
2019-10-07 19:45 ` Pawan Gupta
2019-10-09 6:13 ` Paolo Bonzini
2019-10-09 14:41 ` Pawan Gupta
2019-10-09 15:10 ` Paolo Bonzini
2019-10-10 5:53 ` Pawan Gupta
2019-10-10 16:14 ` Paolo Bonzini
2019-10-10 16:50 ` Paolo Bonzini
2019-10-10 17:37 ` Paolo Bonzini [this message]
[not found] ` <1561989149-17323-7-git-send-email-pbonzini@redhat.com>
[not found] ` <alpine.DEB.2.21.1907022244530.1802@nanos.tec.linutronix.de>
[not found] ` <4c4447ba-838d-cd85-f35b-468508437b61@intel.com>
[not found] ` <alpine.DEB.2.21.1907022303250.1802@nanos.tec.linutronix.de>
2019-10-09 0:14 ` [MODERATED] Re: [PATCH v5 6/8] NX 6 Pawan Gupta
2019-10-09 22:42 ` Ben Hutchings
2019-10-09 22:52 ` Junaid Shahid
2019-10-09 23:05 ` Ben Hutchings
2019-10-09 23:03 ` Kanth Ghatraju
2019-10-09 23:08 ` Paolo Bonzini
2019-10-09 23:20 ` Kanth Ghatraju
2019-10-31 22:54 ` [MODERATED] NX backports (was Re: [PATCH v5 6/8] NX 6) Paolo Bonzini
2019-10-13 22:11 ` [MODERATED] Re: [PATCH v5 6/8] NX 6 Ben Hutchings
2019-10-14 6:57 ` Paolo Bonzini
2019-11-04 19:43 ` mark gross
2019-11-05 12:28 ` [MODERATED] Re: ***UNCHECKED*** " Michal Hocko
2019-11-05 14:53 ` mark gross
2019-11-05 17:03 ` mark gross
2019-10-14 20:46 ` [MODERATED] " Pawan Gupta
2019-10-15 6:24 ` Greg KH
2019-10-15 10:46 ` Jiri Kosina
2019-10-15 21:19 ` Pawan Gupta
2019-10-17 23:50 ` Ben Hutchings
[not found] ` <1561989149-17323-2-git-send-email-pbonzini@redhat.com>
2019-10-09 23:01 ` [MODERATED] Re: [PATCH v5 1/8] NX 1 Ben Hutchings
2019-10-10 1:33 ` Pawan Gupta
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