From a10eadd2d52fc3f4a10563ff13f8f6611b6a6d81 Mon Sep 17 00:00:00 2001
From: Clement Tsang <34804052+ClementTsang@users.noreply.github.com>
Date: Thu, 13 Aug 2026 05:22:40 -0400
Subject: [PATCH] bug: fix cgroups v1 swap collection around sentinel max value
 (#2195)

Problem was that with cgroups v1, if the swap had an unlimited value set, it would be done by just setting a huge integer, which would break things.
---
 CHANGELOG.md                    |  3 ++-
 src/collection.rs               |  6 +++++-
 src/collection/linux/cgroups.rs | 32 ++++++++++++++++++++++++--------
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index dab1e4e9..994cb7fa 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,11 +20,12 @@ That said, these are more guidelines rather than hard rules, though the project
 
 ---
 
-## 0.14.8/0.15.0 - Unreleased
+## 0.14.8 - 2026-08-13
 
 ### Bug Fixes
 
 - [2191](https://github.com/ClementTsang/bottom/pull/2191): Fix close logic when pressing enter in sort menu.
+- [2195](https://github.com/ClementTsang/bottom/pull/2195): Fix cgroups v1 swap collection around sentinel max value.
 
 ## 0.14.7 - 2026-07-27
 
diff --git a/src/collection.rs b/src/collection.rs
index 2711e261..3b158941 100644
--- a/src/collection.rs
+++ b/src/collection.rs
@@ -381,7 +381,11 @@ impl DataCollector {
         self.refresh_sysinfo_data();
 
         #[cfg(target_os = "linux")]
-        self.cgroup_memory_data.refresh();
+        {
+            let total_memory = self.sys.system.total_memory();
+            let total_swap = self.sys.system.total_swap();
+            self.cgroup_memory_data.refresh(total_memory, total_swap);
+        }
 
         #[cfg(target_os = "linux")]
         self.cgroup_cpu_data.refresh();
diff --git a/src/collection/linux/cgroups.rs b/src/collection/linux/cgroups.rs
index 0136f423..7065b0f8 100644
--- a/src/collection/linux/cgroups.rs
+++ b/src/collection/linux/cgroups.rs
@@ -44,19 +44,32 @@ pub(crate) struct CgroupMemCollector {
     pub swap: Option<CgroupMemData>,
 }
 
+/// Computes the cgroup v1 swap limit. Calculated by getting memsw and subtracting the memory limits.
+#[inline]
+fn cgroup_v1_swap_limit(
+    memsw_limit: u64, mem_limit: Option<u64>, total_memory: u64, total_swap: u64,
+) -> u64 {
+    let effective_memsw_limit = memsw_limit.min(total_memory + total_swap);
+    let effective_mem_limit = mem_limit.map_or(0, |mem_limit| mem_limit.min(total_memory));
+
+    effective_memsw_limit.saturating_sub(effective_mem_limit)
+}
+
 impl CgroupMemCollector {
     /// Refresh the cgroup memory data.
     ///
     /// Based on [docker's CLI](https://github.com/docker/cli/blob/master/cli/command/container/stats_helpers.go#L254).
-    pub(crate) fn refresh(&mut self) {
-        if !self.try_update_memory_cgroup_v1() && !self.try_update_memory_cgroup_v2() {
+    pub(crate) fn refresh(&mut self, total_memory: u64, total_swap: u64) {
+        if !self.try_update_memory_cgroup_v1(total_memory, total_swap)
+            && !self.try_update_memory_cgroup_v2()
+        {
             self.ram = None;
             self.swap = None;
         }
     }
 
     /// Try and update the memory using cgroup v1 semantics. If successful, returns `true`.
-    fn try_update_memory_cgroup_v1(&mut self) -> bool {
+    fn try_update_memory_cgroup_v1(&mut self, total_memory: u64, total_swap: u64) -> bool {
         if let Some(mem_usage) = read_u64("/sys/fs/cgroup/memory/memory.usage_in_bytes") {
             // --- Memory ---
             let inactive =
@@ -66,8 +79,8 @@ impl CgroupMemCollector {
                 _ => mem_usage,
             };
 
-            // Technically if it's like, some insanely high value (https://unix.stackexchange.com/a/421182)
-            // then it's "unlimited" but we can just make it so we take the max of the main and this anyway.
+            // Technically if it's some insanely high value (https://unix.stackexchange.com/a/421182),
+            // then it's "unlimited", but we can just make it so we take the max of the main and this anyway.
             let mem_limit_raw = read_u64("/sys/fs/cgroup/memory/memory.limit_in_bytes");
             let mem_limit = mem_limit_raw.map(CgroupMemLimit::Bytes);
 
@@ -78,12 +91,15 @@ impl CgroupMemCollector {
 
             // --- Swap ---
             // Since swap is dependent on the normal memory usage, we couple it together.
-            if let Some(memsw) = read_u64("/sys/fs/cgroup/memory/memory.memsw.usage_in_bytes") {
-                let used_bytes = memsw.saturating_sub(mem_usage);
+            if let Some(memsw_usage) = read_u64("/sys/fs/cgroup/memory/memory.memsw.usage_in_bytes")
+            {
+                let used_bytes = memsw_usage.saturating_sub(mem_usage);
 
                 // Same idea for here.
                 let swap_limit = read_u64("/sys/fs/cgroup/memory/memory.memsw.limit_in_bytes")
-                    .map(|memsw_limit| memsw_limit.saturating_sub(mem_limit_raw.unwrap_or(0)))
+                    .map(|memsw_limit| {
+                        cgroup_v1_swap_limit(memsw_limit, mem_limit_raw, total_memory, total_swap)
+                    })
                     .map(CgroupMemLimit::Bytes);
 
                 self.swap = Some(CgroupMemData {