* Ivan Ren (reny...@gmail.com) wrote:
> Reproduce the problem:
> migrate
> migrate_cancel
> migrate
>
> Error happen for memory migration
Can we fix this by just reverting 03158519384 ?
Dave
> 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.
>
> Signed-off-by: Ivan Ren <ivan...@tencent.com>
> ---
> migration/ram.c | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 908517fc2b..bbebaee0c1 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -3173,11 +3173,11 @@ static int ram_state_init(RAMState **rsp)
> QSIMPLEQ_INIT(&(*rsp)->src_page_requests);
>
> /*
> + * Count the total number of pages used by ram blocks not including any
> + * gaps due to alignment or unplugs.
> * This must match with the initial values of dirty bitmap.
> - * Currently we initialize the dirty bitmap to all zeros so
> - * here the total dirty page count is zero.
> */
> - (*rsp)->migration_dirty_pages = 0;
> + (*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
> ram_state_reset(*rsp);
>
> return 0;
> @@ -3196,12 +3196,13 @@ static void ram_list_init_bitmaps(void)
> * The initial dirty bitmap for migration must be set with all
> * ones to make sure we'll migrate every guest RAM page to
> * destination.
> - * Here we didn't set RAMBlock.bmap simply because it is already
> - * set in ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] in
> - * ram_block_add, and that's where we'll sync the dirty bitmaps.
> - * Here setting RAMBlock.bmap would be fine too but not
> necessary.
> + * Here we set RAMBlock.bmap all to 1 because when rebegin a
> + * new migration after a failed migration, ram_list.
> + * dirty_memory[DIRTY_MEMORY_MIGRATION] don't include the whole
> + * guest memory.
> */
> block->bmap = bitmap_new(pages);
> + bitmap_set(block->bmap, 0, pages);
> if (migrate_postcopy_ram()) {
> block->unsentmap = bitmap_new(pages);
> bitmap_set(block->unsentmap, 0, pages);
> --
> 2.17.2 (Apple Git-113)
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
