Re: [Qemu-devel] [PATCH] migration: always initial RAMBlock.bmap to 1 for new migration

[Peter Xu <zhexu@redhat.com>]

On Sun, Jul 14, 2019 at 10:51:19PM +0800, Ivan Ren wrote:
> Reproduce the problem:
> migrate
> migrate_cancel
> migrate
> 
> Error happen for memory migration

Can mention "this mostly revert 0315851938 but with comments kept"
when merge...

> 
> The reason as follows:
> 1. qemu start, ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] all set to
>    1 by a series of cpu_physical_memory_set_dirty_range
> 2. migration start:ram_init_bitmaps
>    - memory_global_dirty_log_start: begin log diry
>    - memory_global_dirty_log_sync: sync dirty bitmap to
>      ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION]
>    - migration_bitmap_sync_range: sync ram_list.
>      dirty_memory[DIRTY_MEMORY_MIGRATION] to RAMBlock.bmap
>      and ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] is set to zero
> 3. migration data...
> 4. migrate_cancel, will stop log dirty
> 5. migration start:ram_init_bitmaps
>    - memory_global_dirty_log_start: begin log diry
>    - memory_global_dirty_log_sync: sync dirty bitmap to
>      ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION]
>    - migration_bitmap_sync_range: sync ram_list.
>      dirty_memory[DIRTY_MEMORY_MIGRATION] to RAMBlock.bmap
>      and ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] is set to zero
> 
>    Here RAMBlock.bmap only have new logged dirty pages, don't contain
>    the whole guest pages.

Fixes: 03158519384f158

> 
> Signed-off-by: Ivan Ren <ivanren@tencent.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

I think this is a bit severe and should be rc2 material.  Dave/Juan?

Thanks,

-- 
Peter Xu