linux-kernel - Re: [PATCH V5 0/9] Fixes for vhost metadata acceleration

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Message-ID: <9325de4b-1d79-eb19-306e-e7a8fa8cc1a5@redhat.com>
Date:   Tue, 20 Aug 2019 10:29:32 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, jgg@...pe.ca
Subject: Re: [PATCH V5 0/9] Fixes for vhost metadata acceleration


On 2019/8/20 上午5:08, Michael S. Tsirkin wrote:
> On Tue, Aug 13, 2019 at 04:12:49PM +0800, Jason Wang wrote:
>> On 2019/8/12 下午5:49, Michael S. Tsirkin wrote:
>>> On Mon, Aug 12, 2019 at 10:44:51AM +0800, Jason Wang wrote:
>>>> On 2019/8/11 上午1:52, Michael S. Tsirkin wrote:
>>>>> On Fri, Aug 09, 2019 at 01:48:42AM -0400, Jason Wang wrote:
>>>>>> Hi all:
>>>>>>
>>>>>> This series try to fix several issues introduced by meta data
>>>>>> accelreation series. Please review.
>>>>>>
>>>>>> Changes from V4:
>>>>>> - switch to use spinlock synchronize MMU notifier with accessors
>>>>>>
>>>>>> Changes from V3:
>>>>>> - remove the unnecessary patch
>>>>>>
>>>>>> Changes from V2:
>>>>>> - use seqlck helper to synchronize MMU notifier with vhost worker
>>>>>>
>>>>>> Changes from V1:
>>>>>> - try not use RCU to syncrhonize MMU notifier with vhost worker
>>>>>> - set dirty pages after no readers
>>>>>> - return -EAGAIN only when we find the range is overlapped with
>>>>>>      metadata
>>>>>>
>>>>>> Jason Wang (9):
>>>>>>      vhost: don't set uaddr for invalid address
>>>>>>      vhost: validate MMU notifier registration
>>>>>>      vhost: fix vhost map leak
>>>>>>      vhost: reset invalidate_count in vhost_set_vring_num_addr()
>>>>>>      vhost: mark dirty pages during map uninit
>>>>>>      vhost: don't do synchronize_rcu() in vhost_uninit_vq_maps()
>>>>>>      vhost: do not use RCU to synchronize MMU notifier with worker
>>>>>>      vhost: correctly set dirty pages in MMU notifiers callback
>>>>>>      vhost: do not return -EAGAIN for non blocking invalidation too early
>>>>>>
>>>>>>     drivers/vhost/vhost.c | 202 +++++++++++++++++++++++++-----------------
>>>>>>     drivers/vhost/vhost.h |   6 +-
>>>>>>     2 files changed, 122 insertions(+), 86 deletions(-)
>>>>> This generally looks more solid.
>>>>>
>>>>> But this amounts to a significant overhaul of the code.
>>>>>
>>>>> At this point how about we revert 7f466032dc9e5a61217f22ea34b2df932786bbfc
>>>>> for this release, and then re-apply a corrected version
>>>>> for the next one?
>>>> If possible, consider we've actually disabled the feature. How about just
>>>> queued those patches for next release?
>>>>
>>>> Thanks
>>> Sorry if I was unclear. My idea is that
>>> 1. I revert the disabled code
>>> 2. You send a patch readding it with all the fixes squashed
>>> 3. Maybe optimizations on top right away?
>>> 4. We queue *that* for next and see what happens.
>>>
>>> And the advantage over the patchy approach is that the current patches
>>> are hard to review. E.g.  it's not reasonable to ask RCU guys to review
>>> the whole of vhost for RCU usage but it's much more reasonable to ask
>>> about a specific patch.
>>
>> Ok. Then I agree to revert.
>>
>> Thanks
> Great, so please send the following:
> - revert
> - squashed and fixed patch


Just to confirm, do you want me to send a single series or two?

Thanks