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

[Dr. David Alan Gilbert]

* Peter Xu (address@hidden) wrote:
> 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 <address@hidden>
> 
> Reviewed-by: Peter Xu <address@hidden>
> 
> I think this is a bit severe and should be rc2 material.  Dave/Juan?

Yes agreed; I've added it to the planning/4.1 page.

> Thanks,
> 
> -- 
> Peter Xu
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK