Re: [PATCH v9 0/7] Allow to enable multifd and postcopy migration together

[Fabiano Rosas <farosas@suse.de>]

Prasad Pandit <ppandit@redhat.com> writes:

> On Tue, 29 Apr 2025 at 18:34, Peter Xu <peterx@redhat.com> wrote:
>> I think that's what Fabiano mentioned, but ultimately we need to verify it
>> on a reproducer to know.
> ...
>> Looks ok, but please add some comments explain why postcopy needs to do it,
>> and especially do it during precopy phase.
>>
>> I'd use migrate_postcopy_ram() instead.
>
> * Okay. It should be '||' instead of '&&' in the first conditional I
> think, we want to write zeropage when postcopy is enabled.
> ===
> diff --git a/migration/multifd-zero-page.c b/migration/multifd-zero-page.c
> index dbc1184921..4d6677feab 100644
> --- a/migration/multifd-zero-page.c
> +++ b/migration/multifd-zero-page.c
> @@ -85,9 +85,11 @@ void multifd_recv_zero_page_process(MultiFDRecvParams *p)
>  {
>      for (int i = 0; i < p->zero_num; i++) {
>          void *page = p->host + p->zero[i];
> -        if (ramblock_recv_bitmap_test_byte_offset(p->block, p->zero[i])) {
> +        if (migrate_postcopy_ram() ||
> +            ramblock_recv_bitmap_test_byte_offset(p->block, p->zero[i])) {
>              memset(page, 0, multifd_ram_page_size());
> -        } else {
> +        }
> +        if (!ramblock_recv_bitmap_test_byte_offset(p->block, p->zero[i])) {
>              ramblock_recv_bitmap_set_offset(p->block, p->zero[i]);
>          }
>      }
> ===

I applied this diff and I'm not seeing the hang anymore.