Re: [Qemu-devel] [PATCH 1/3] migration: fix migrate_cancel leads live_migration thread endless loop

[Juan Quintela <quintela@redhat.com>]

Ivan Ren <renyime@gmail.com> wrote:
> When we 'migrate_cancel' a multifd migration, live_migration thread may
> go into endless loop in multifd_send_pages functions.
>
> Reproduce steps:
>
> (qemu) migrate_set_capability multifd on
> (qemu) migrate -d url
> (qemu) [wait a while]
> (qemu) migrate_cancel
>
> Then may get live_migration 100% cpu usage in following stack:
>
> pthread_mutex_lock
> qemu_mutex_lock_impl
> multifd_send_pages
> multifd_queue_page
> ram_save_multifd_page
> ram_save_target_page
> ram_save_host_page
> ram_find_and_save_block
> ram_find_and_save_block
> ram_save_iterate
> qemu_savevm_state_iterate
> migration_iteration_run
> migration_thread
> qemu_thread_start
> start_thread
> clone
>
> Signed-off-by: Ivan Ren <ivanren@tencent.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

Will sent for rc3.