On Thu, Mar 21, 2024 at 05:12:42PM -0300, Fabiano Rosas wrote:
> When the zero page detection is done in the multifd threads, we need
> to iterate the second part of the pages->offset array and clear the
> file bitmap for each zero page. The piece of code we merged to do that
> is wrong.
>
> The reason this has passed all the tests is because the bitmap is
> initialized with zeroes already, so clearing the bits only really has
> an effect during live migration and when a data page goes from having
> data to no data.
>
> Fixes: 303e6f54f9 ("migration/multifd: Implement zero page transmission on
> the multifd thread.")
> Signed-off-by: Fabiano Rosas <faro...@suse.de>
> ---
> CI run: https://gitlab.com/farosas/qemu/-/pipelines/1222882269
> ---
> migration/multifd.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/migration/multifd.c b/migration/multifd.c
> index d2f0238f70..2802afe79d 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -111,7 +111,6 @@ void multifd_send_channel_created(void)
> static void multifd_set_file_bitmap(MultiFDSendParams *p)
> {
> MultiFDPages_t *pages = p->pages;
> - uint32_t zero_num = p->pages->num - p->pages->normal_num;
>
> assert(pages->block);
>
> @@ -119,7 +118,7 @@ static void multifd_set_file_bitmap(MultiFDSendParams *p)
> ramblock_set_file_bmap_atomic(pages->block, pages->offset[i], true);
> }
>
> - for (int i = p->pages->num; i < zero_num; i++) {
> + for (int i = p->pages->normal_num; i < p->pages->num; i++) {
> ramblock_set_file_bmap_atomic(pages->block, pages->offset[i], false);
> }
> }
Hmm, a challenging one even if it reads obvious.. :)
queued for 9.0-rc1, thanks.
--
Peter Xu
