From 97ca211c6216ccfcb64c46f739a0ce36042d9ea8 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Mon, 23 Jul 2018 20:33:03 +0800 Subject: [PATCH] migration: disallow recovery for release-ram Postcopy recovery won't work well with release-ram capability since release-ram will drop the page buffer as long as the page is put into the send buffer. So if there is a network failure happened, any page buffers that have not yet reached the destination VM but have already been sent from the source VM will be lost forever. Let's refuse the client from resuming such a postcopy migration. Luckily release-ram was designed to only be used when src and destination VMs are on the same host, so it should be fine. Signed-off-by: Peter Xu Message-Id: <20180723123305.24792-3-peterx@redhat.com> Reviewed-by: Juan Quintela Signed-off-by: Dr. David Alan Gilbert --- migration/migration.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/migration/migration.c b/migration/migration.c index db6bde7453..bfc4d09aae 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1629,6 +1629,25 @@ static bool migrate_prepare(MigrationState *s, bool blk, bool blk_inc, "paused migration"); return false; } + + /* + * Postcopy recovery won't work well with release-ram + * capability since release-ram will drop the page buffer as + * long as the page is put into the send buffer. So if there + * is a network failure happened, any page buffers that have + * not yet reached the destination VM but have already been + * sent from the source VM will be lost forever. Let's refuse + * the client from resuming such a postcopy migration. + * Luckily release-ram was designed to only be used when src + * and destination VMs are on the same host, so it should be + * fine. + */ + if (migrate_release_ram()) { + error_setg(errp, "Postcopy recovery cannot work " + "when release-ram capability is set"); + return false; + } + /* This is a resume, skip init status */ return true; }