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Merged
JamesC1305 merged 2 commits into from
Dec 15, 2025
+28 −26
Merged

feat(balloon): add logging for malformed balloon-stats tag #5572

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8ab6410
feat(balloon): add logging for malformed balloon-stats tag
22aronl Dec 8, 2025
3786231
Merge branch 'main' into balloon-stat-warn
JamesC1305 Dec 15, 2025
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48 changes: 22 additions & 26 deletions src/vmm/src/devices/virtio/balloon/device.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ use std::ops::Deref;
use std::sync::Arc;
use std::time::Duration;

use log::{error, info, warn};
use log::{debug, error, info, warn};
use serde::{Deserialize, Serialize};
use utils::time::TimerFd;
use vmm_sys_util::eventfd::EventFd;
Expand Down Expand Up @@ -207,7 +207,7 @@ pub struct BalloonStats {
}

impl BalloonStats {
fn update_with_stat(&mut self, stat: &BalloonStat) -> Result<(), BalloonError> {
fn update_with_stat(&mut self, stat: &BalloonStat) {
let val = Some(stat.val);
match stat.tag {
VIRTIO_BALLOON_S_SWAP_IN => self.swap_in = val,
Expand All @@ -226,12 +226,11 @@ impl BalloonStats {
VIRTIO_BALLOON_S_DIRECT_SCAN => self.direct_scan = val,
VIRTIO_BALLOON_S_ASYNC_RECLAIM => self.async_reclaim = val,
VIRTIO_BALLOON_S_DIRECT_RECLAIM => self.direct_reclaim = val,
_ => {
return Err(BalloonError::MalformedPayload);
tag => {
METRICS.stats_update_fails.inc();
debug!("balloon: unknown stats update tag: {tag}");
}
}

Ok(())
}
}

Expand Down Expand Up @@ -503,10 +502,7 @@ impl Balloon {
let stat = mem
.read_obj::<BalloonStat>(addr)
.map_err(|_| BalloonError::MalformedDescriptor)?;
self.latest_stats.update_with_stat(&stat).map_err(|_| {
METRICS.stats_update_fails.inc();
BalloonError::MalformedPayload
})?;
self.latest_stats.update_with_stat(&stat);
}

self.stats_desc_index = Some(head.index);
Expand Down Expand Up @@ -1067,52 +1063,52 @@ pub(crate) mod tests {
val: 1,
};

stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.swap_in, Some(1));
stat.tag = VIRTIO_BALLOON_S_SWAP_OUT;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.swap_out, Some(1));
stat.tag = VIRTIO_BALLOON_S_MAJFLT;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.major_faults, Some(1));
stat.tag = VIRTIO_BALLOON_S_MINFLT;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.minor_faults, Some(1));
stat.tag = VIRTIO_BALLOON_S_MEMFREE;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.free_memory, Some(1));
stat.tag = VIRTIO_BALLOON_S_MEMTOT;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.total_memory, Some(1));
stat.tag = VIRTIO_BALLOON_S_AVAIL;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.available_memory, Some(1));
stat.tag = VIRTIO_BALLOON_S_CACHES;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.disk_caches, Some(1));
stat.tag = VIRTIO_BALLOON_S_HTLB_PGALLOC;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.hugetlb_allocations, Some(1));
stat.tag = VIRTIO_BALLOON_S_HTLB_PGFAIL;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.hugetlb_failures, Some(1));
stat.tag = VIRTIO_BALLOON_S_OOM_KILL;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.oom_kill, Some(1));
stat.tag = VIRTIO_BALLOON_S_ALLOC_STALL;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.alloc_stall, Some(1));
stat.tag = VIRTIO_BALLOON_S_ASYNC_SCAN;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.async_scan, Some(1));
stat.tag = VIRTIO_BALLOON_S_DIRECT_SCAN;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.direct_scan, Some(1));
stat.tag = VIRTIO_BALLOON_S_ASYNC_RECLAIM;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.async_reclaim, Some(1));
stat.tag = VIRTIO_BALLOON_S_DIRECT_RECLAIM;
stats.update_with_stat(&stat).unwrap();
stats.update_with_stat(&stat);
assert_eq!(stats.direct_reclaim, Some(1));
}

Expand Down
6 changes: 6 additions & 0 deletions tests/integration_tests/functional/test_balloon.py
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Original file line number Diff line number Diff line change
Expand Up @@ -320,6 +320,9 @@ def test_stats(uvm_plain_any):
# Get another reading of the stats after the polling interval has passed.
deflated_stats = test_microvm.api.balloon_stats.get().json()

# Ensure that stats don't have unknown balloon stats fields
assert "balloon: unknown stats update tag:" not in test_microvm.log_data

# Ensure the stats reflect deflating the balloon.
assert inflated_stats["free_memory"] < deflated_stats["free_memory"]
assert inflated_stats["available_memory"] < deflated_stats["available_memory"]
Expand Down Expand Up @@ -372,6 +375,9 @@ def test_stats_update(uvm_plain_any):
final_stats = test_microvm.api.balloon_stats.get().json()
assert next_stats["available_memory"] != final_stats["available_memory"]

# Ensure that stats don't have unknown balloon stats fields
assert "balloon: unknown stats update tag:" not in test_microvm.log_data


def test_balloon_snapshot(uvm_plain_any, microvm_factory):
"""
Expand Down