Re: [libvirt] Syslog "nested job is dangerous" message

On 07/16/2014 07:52 PM, Sam Bobroff wrote: > Hello everyone, [Can you configure your mailer to wrap long lines?]

> After performing a migration, the syslog often contains several > messages like this: > > "This thread seems to be the async job owner; entering monitor > without asking for a nested job is dangerous" The sign of a bug that we need to fix. What version of libvirt are you using? We may have already fixed it.

> The message makes it sound as if the user has done something > dangerous but, after looking at the code that produces the message, > it appears to be more to do with how the libvirt job code is used. Rather, libvirt itself has done something dangerous. > > The commit that added the warning > (6eede368bc8e3df2c94c2ec1a913885ce08e99db) doesn't explain why it > might be dangerous... Jiri can probably explain better, but it means there is a race condition where libvirt can lose track of a long-running job and cause memory corruption in its management of the guest. > Would it be appropriate to re-word the message, or perhaps change > it to a debug message so that it's not normally seen by users? No. > > Is it important to track down the cases that are generating the > warning and fix them? (Could it cause some kind of significant > problem?) Yes.