[PATCH v3] vhost: exclude VM hugepages from coredumps

[Maxime Coquelin]

Hi Mike,

On 2/10/23 22:12, Mike Pattrick wrote:
> On Fri, Feb 10, 2023 at 10:53 AM David Marchand
> <david.marchand at redhat.com> wrote:
>>
>> Hello Mike,
>>
>> On Wed, Dec 7, 2022 at 5:54 PM Mike Pattrick <mkp at redhat.com> wrote:
>>>
>>> Currently if an application wants to include shared hugepages in
>>> coredumps in conjunction with the vhost library, the coredump will be
>>> larger than expected and include unneeded virtual machine memory.
>>>
>>> This patch will mark all vhost huge pages as DONTDUMP, except for some
>>> select pages used by DPDK.
>>>
>>> Signed-off-by: Mike Pattrick <mkp at redhat.com>
>>
>> I noticed the following warnings today on my f37 kernel, while running
>> a vhost-user/virtio-user testpmd setup on next-virtio branch.
>> Linux dmarchan 6.1.9-200.fc37.x86_64 #1 SMP PREEMPT_DYNAMIC Thu Feb  2
>> 00:21:48 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
>> My system has 2M hugepages, only.
>>
>>
>> $ rm vhost-net; strace -e trace=madvise -f
>> ./build-clang/app/dpdk-testpmd --in-memory --no-pci
>> --vdev=net_vhost0,iface=./vhost-net,client=1 -- -i
>>
>> $ ./build-clang/app/dpdk-testpmd --in-memory --single-file-segment
>> --no-pci --vdev
>> 'net_virtio_user0,mac=00:01:02:03:04:05,path=./vhost-net,server=1'  --
>> -i
>>
>> Then, on the "vhost side" testpmd:
>> ...
>> VHOST_CONFIG: (./vhost-net) read message VHOST_USER_SET_VRING_NUM
>> VHOST_CONFIG: (./vhost-net) read message VHOST_USER_SET_VRING_BASE
>> VHOST_CONFIG: (./vhost-net) vring base idx:0 last_used_idx:0 last_avail_idx:0.
>> VHOST_CONFIG: (./vhost-net) read message VHOST_USER_SET_VRING_ADDR
>> VHOST_CONFIG: (./vhost-net) read message VHOST_USER_SET_VRING_KICK
>> VHOST_CONFIG: (./vhost-net) vring kick idx:0 file:391
>> [pid 59565] madvise(0x7fa6d8da4000, 2052, MADV_DODUMP) = -1 EINVAL
>> (Invalid argument)
>> VHOST_CONFIG: could not set coredump preference (Invalid argument).
>> [pid 59565] madvise(0x7fa6d8da5000, 2052, MADV_DODUMP) = -1 EINVAL
>> (Invalid argument)
>> VHOST_CONFIG: could not set coredump preference (Invalid argument).
>> [pid 59565] madvise(0x7fa6d8da6000, 2052, MADV_DODUMP) = -1 EINVAL
>> (Invalid argument)
>> VHOST_CONFIG: could not set coredump preference (Invalid argument).
>> VHOST_CONFIG: (./vhost-net) read message VHOST_USER_SET_VRING_NUM
>> VHOST_CONFIG: (./vhost-net) read message VHOST_USER_SET_VRING_BASE
>>
>> Looking at the whole trace, only madvise calls with MADV_DODUMP (with
>> all of them for a 2052 size) fail.
>>
>> I did not investigate further.
>> Could you have a look please?
>>
> 
> I tried it on that exact kernel and also ran into this issue. I'll
> check it out in more depth.

Gentle reminder, have you found the root cause for this issue?

Thanks,
Maxime

> -M
> 
>>
>> --
>> David Marchand
>>
>