Re: [PATCH v2] migration: Fix blocking in POSTCOPY_DEVICE during package load

[Juraj Marcin <jmarcin@redhat.com>]

Hi Peter,

On 2026-04-23 15:12, Peter Xu wrote:
> On Thu, Apr 23, 2026 at 03:14:38PM +0530, Pranav Tyagi wrote:
> > The package_loaded event is not set in case MIG_RP_MSG_PONG does not
> > arrive on the source from the destination in the return path thread. The
> > migration thread would then be blocked waiting for package_loaded event
> > indefinitely in POSTCOPY_DEVICE state. Where as, in such a condition the
> > source VM can safely resume as the destination has not yet started. The
> > pong message can get lost in case of a network failure or destination
> > crash before sending the pong.
> > 
> > This patch removes the package_loaded event and uses rp_sem, instead of
> > kicking multiple events. The error is detected in case of network
> > failure or destination crash and rp_sem is set in the out path of the
> > return path thread. This will kick the migration thread out from a
> > condition of indefinitely waiting for rp_sem. The migration thread then
> > fails early and breaks from the migration loop to resume the vm on the
> > source side.
> > 
> > Fixes: 7b842fe354c6 ("migration: Introduce POSTCOPY_DEVICE state")
> > Signed-off-by: Pranav Tyagi <prtyagi@redhat.com>
> 
> Reviewed-by: Peter Xu <peterx@redhat.com>
> 
> I assume Juraj has looked at this already internally, in that case you can
> always attach his R-b directly when post / repost.

I did indeed check it, you can include by R-b!

> 
> If not, then it becomes a sincere request.. :-D
> 
> Thanks!
> 
> -- 
> Peter Xu
>