Commit 40c4d4a8 authored by Ivan Ren's avatar Ivan Ren Committed by Juan Quintela
Browse files

migration: always initial RAMBlock.bmap to 1 for new migration 



Reproduce the problem:
migrate
migrate_cancel
migrate

Error happen for memory migration

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: default avatarIvan Ren <ivanren@tencent.com>
Reviewed-by: default avatarJuan Quintela <quintela@redhat.com>
Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Message-Id: <1563115879-2715-1-git-send-email-ivanren@tencent.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent 40277ca8

migration/ram.c

+8 −7
Original line number Diff line number Diff line
@@ -3213,11 +3213,11 @@ 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;
@@ -3249,12 +3249,13 @@ 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);

            block->clear_bmap_shift = shift;

            block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift));

            if (migrate_postcopy_ram()) {