On 28/03/2024 17:21, Cédric Le Goater wrote:
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Hello Avihai,
On 3/28/24 15:02, Avihai Horon wrote:
After commit 9425ef3f990a ("migration: Use migrate_has_error() in
close_return_path_on_source()"), close_return_path_on_source() assumes
that migration error is set if an error occurs during migration.
This may not be true if migration errors in migration_completion(). For
example, if qemu_savevm_state_complete_precopy() errors, migration error
will not be set
Out of curiosity, could you describe a bit more the context ? Did
vfio_save_complete_precopy() fail ? why ?
Yep, vfio_save_complete_precopy() failed (but it failed while I was
experimenting with an unofficial debug FW).
We should propagate errors of .save_live_complete_precopy() handlers as
it was done .save_setup handlers(). For 9.1.
Agreed.
This in turn, will cause a migration hang bug, similar to the bug that
was fixed by commit 22b04245f0d5 ("migration: Join the return path
thread before releasing to_dst_file"), as shutdown() will not be issued
for the return-path channel.
yes, but this test :
if (ret < 0) {
goto fail;
}
will skip the close_return_path_on_source() call. Won't it ? So I don't
understand how it can be an issue. Am I missing something ?
It will skip the close_return_path_on_source() call in
migration_completion(), but there is another
close_return_path_on_source() call in migrate_fd_cleanup().
Fix it by ensuring migration error is set in case of error in
migration_completion().
Why didn't you add a reference to commit 9425ef3f990a ?
I thought this commit didn't introduce this bug, but looking again in
the mailing list [1], it kinda did:
The hang bug was fully fixed by commit 22b04245f0d ("migration: Join the
return path thread before releasing to_dst_file") and then 9425ef3f990a
re-introduced the bug, but only for migration_completion() case.
So, you are right, a fixes line with 9425ef3f990a should be added.
Thanks.
[1] https://lore.kernel.org/all/20240226203122.22894-1-faro...@suse.de/
Signed-off-by: Avihai Horon <avih...@nvidia.com>
---
migration/migration.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/migration/migration.c b/migration/migration.c
index 9fe8fd2afd7..b73ae3a72c4 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2799,6 +2799,7 @@ static void migration_completion(MigrationState
*s)
{
int ret = 0;
int current_active_state = s->state;
+ Error *local_err = NULL;
if (s->state == MIGRATION_STATUS_ACTIVE) {
ret = migration_completion_precopy(s, ¤t_active_state);
@@ -2832,6 +2833,15 @@ static void
migration_completion(MigrationState *s)
return;
fail:
+ if (qemu_file_get_error_obj(s->to_dst_file, &local_err)) {
+ migrate_set_error(s, local_err);
+ error_free(local_err);
+ } else if (ret) {
+ error_setg_errno(&local_err, -ret, "Error in migration
completion");
The 'ret = -1' case could be improved with error_setg(). As a followup.
Thanks,
C.
+ migrate_set_error(s, local_err);
+ error_free(local_err);
+ }
+
migration_completion_failed(s, current_active_state);
}
