diff options
author | Peter Xu <peterx@redhat.com> | 2022-10-04 14:24:26 -0400 |
---|---|---|
committer | Juan Quintela <quintela@redhat.com> | 2022-11-21 11:58:10 +0100 |
commit | 4934a5dd7c68f5ab15f17498db4fc20ed6db9578 (patch) | |
tree | 6c7a43e0acaf1706ae878c1caecf2ca0d5f4940f /migration | |
parent | 4cc47b439594327b213f9b6a67803f1a503c2cb7 (diff) | |
download | qemu-4934a5dd7c68f5ab15f17498db4fc20ed6db9578.zip qemu-4934a5dd7c68f5ab15f17498db4fc20ed6db9578.tar.gz qemu-4934a5dd7c68f5ab15f17498db4fc20ed6db9578.tar.bz2 |
migration: Fix possible infinite loop of ram save process
When starting ram saving procedure (especially at the completion phase),
always set last_seen_block to non-NULL to make sure we can always correctly
detect the case where "we've migrated all the dirty pages".
Then we'll guarantee both last_seen_block and pss.block will be valid
always before the loop starts.
See the comment in the code for some details.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Diffstat (limited to 'migration')
-rw-r--r-- | migration/ram.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/migration/ram.c b/migration/ram.c index dc1de9d..1d42414 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2546,14 +2546,22 @@ static int ram_find_and_save_block(RAMState *rs) return pages; } + /* + * Always keep last_seen_block/last_page valid during this procedure, + * because find_dirty_block() relies on these values (e.g., we compare + * last_seen_block with pss.block to see whether we searched all the + * ramblocks) to detect the completion of migration. Having NULL value + * of last_seen_block can conditionally cause below loop to run forever. + */ + if (!rs->last_seen_block) { + rs->last_seen_block = QLIST_FIRST_RCU(&ram_list.blocks); + rs->last_page = 0; + } + pss.block = rs->last_seen_block; pss.page = rs->last_page; pss.complete_round = false; - if (!pss.block) { - pss.block = QLIST_FIRST_RCU(&ram_list.blocks); - } - do { again = true; found = get_queued_page(rs, &pss); |