Re: [Qemu-devel] [RFC v3 0/8] Fix QEMU crash during memory hotplug with vhost=on

[Andrey Korolyov]

On Wed, Jul 15, 2015 at 7:08 PM, Michael S. Tsirkin <address@hidden> wrote:
> On Wed, Jul 15, 2015 at 06:26:03PM +0300, Andrey Korolyov wrote:
>> On Wed, Jul 15, 2015 at 6:18 PM, Igor Mammedov <address@hidden> wrote:
>> > On Thu, 9 Jul 2015 20:04:35 +0300
>> > Andrey Korolyov <address@hidden> wrote:
>> >
>> >> On Wed, Jul 8, 2015 at 6:46 PM, Igor Mammedov <address@hidden> wrote:
>> >> > On Wed, 8 Jul 2015 13:01:05 +0300
>> >> > "Michael S. Tsirkin" <address@hidden> wrote:
>> >> >
>> >> > [...]
>> >> >> - this fixes qemu on current kernels, so it's a bugfix
>> >> >>
>> >> >> - this changes the semantics of memory hot unplug slightly
>> >> >>   so I think it's important to merge in 2.4 before we
>> >> >>   release qemu with memory hot unplug, this way we
>> >> >>   won't have to maintain old semantics forever
>> >> > concerning semantic change, I've just chatted with Peter
>> >> > who implemented libvirt side of the memory hotplug stack.
>> >> > And it's not a problem for libvirt since it always does
>> >> > unplug dimm -> remove backend sequence.
>> >> >
>> >> >
>> >>
>> >>
>> >> Just for the record - top of the series somehow fixed mysterious guest
>> >> memory corruption issue described in
>> >> https://lists.gnu.org/archive/html/qemu-devel/2015-06/msg03117.html
>> >> which existed right from a moment of a memory hotplug introduction, I
>> >> checked series for its disappearance only with vhost for now.  Thanks
>> >> Igor!
>> > just to be sure which patch exactly fixed issue for you?
>> >
>>
>> Had not bisected this yet, 2.3 is fairly distant from mine production
>> yet... will post a result today or tomorrow. Until then, I`ll be
>> absolutely out of clues of what was behind mentioned corruption.
>
> Igor merely asked which of his 8 patches fixed it.

I mentioned exactly the same thing - right now I`m bisecting over his
series from abovementioned branch to find out what commit fixes the
issue, it should take about a hour for completion of the test series.
The expression is about nature of the bug, as it should be ultimately
weird or well-hidded, given conditions of its exposure.