Messages in this thread Patches in this message | | | Date | Mon, 26 Sep 2022 14:32:24 +0200 | Subject | Re: [PATCH v3 6/6] freezer,sched: Rewrite core freezer logic | From | Christian Borntraeger <> |
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Am 26.09.22 um 12:55 schrieb Christian Borntraeger: > > > Am 26.09.22 um 10:06 schrieb Christian Borntraeger: >> >> >> Am 23.09.22 um 09:53 schrieb Christian Borntraeger: >>> Am 23.09.22 um 09:21 schrieb Christian Borntraeger: >>>> Peter, >>>> >>>> as a heads-up. This commit (bisected and verified) triggers a >>>> regression in our KVM on s390x CI. The symptom is that a specific >>>> testcase (start a guest with next kernel and a poky ramdisk, >>>> then ssh via vsock into the guest and run the reboot command) now >>>> takes much longer (300 instead of 20 seconds). From a first look >>>> it seems that the sshd takes very long to end during shutdown >>>> but I have not looked into that yet. >>>> Any quick idea? >>>> >>>> Christian >>> >>> the sshd seems to hang in virtio-serial (not vsock). >> >> FWIW, sshd does not seem to hang, instead it seems to busy loop in >> wait_port_writable calling into the scheduler over and over again. > > -#define TASK_FREEZABLE 0x00002000 > +#define TASK_FREEZABLE 0x00000000 > > "Fixes" the issue. Just have to find out which of users is responsible.
So it seems that my initial test was not good enough.
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 9fa3c76a267f..e93df4f735fe 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -790,7 +790,7 @@ static int wait_port_writable(struct port *port, bool nonblock) if (nonblock) return -EAGAIN; - ret = wait_event_freezable(port->waitqueue, + ret = wait_event_interruptible(port->waitqueue, !will_write_block(port)); if (ret < 0) return ret; Does fix the problem. My initial test was the following
--- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -790,10 +790,8 @@ static int wait_port_writable(struct port *port, bool nonblock) if (nonblock) return -EAGAIN; - ret = wait_event_freezable(port->waitqueue, + wait_event(port->waitqueue, !will_write_block(port)); - if (ret < 0) - return ret; } /* Port got hot-unplugged. */ if (!port->guest_connected) and obviously it did not provide an exit path.
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