RDKEMW-15176: set swap memory limit for containers by goruklu · Pull Request #419 · rdkcentral/Dobby

goruklu · 2026-03-09T20:49:25Z

Added "swap" limit in the OCI config templates to enable OOM killing when memory limit is reached when swap memory is enabled.

Description

What does this PR change/fix and why?

If there is a corresponding JIRA ticket, please ensure it is in the title of the PR.

Test Procedure

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Type of Change

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to not work as expected)
Other (doesn't fit into the above categories - e.g. documentation updates)

Requires Bitbake Recipe changes?

The base Bitbake recipe (meta-rdk-ext/recipes-containers/dobby/dobby.bb) must be modified to support the changes in this PR (beyond updating SRC_REV)

Added "swap" limit in the OCI config templates to enable OOM killing when memory limit is reached when swap memory is enabled. Signed-off-by: Gurdal Oruklu <gurdal_oruklu@comcast.com>

Copilot

Pull request overview

This PR updates Dobby’s OCI config generation to include a memory swap limit (and swappiness) alongside the existing memory limit, aiming to ensure containers are OOM-killed when memory constraints are hit even if host swap is enabled.

Changes:

Add "swap" and "swappiness" fields to the OCI JSON templates’ linux.resources.memory section.
Introduce a new template variable (MEM_SWAP_LIMIT) and populate it in DobbySpecConfig::processMemLimit as memLimit + 200MB.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

File	Description
bundle/lib/source/templates/OciConfigJsonVM1.0.2-dobby.template	Adds `swap` and `swappiness` to the VM OCI memory cgroup template section.
bundle/lib/source/templates/OciConfigJson1.0.2-dobby.template	Adds `swap` and `swappiness` to the standard OCI memory cgroup template section.
bundle/lib/source/DobbySpecConfig.cpp	Adds `MEM_SWAP_LIMIT` template key and computes it from `memLimit` plus a fixed extra.

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Copilot · 2026-03-09T20:53:09Z

bundle/lib/source/DobbySpecConfig.cpp

@@ -1274,6 +1278,7 @@ bool DobbySpecConfig::processMemLimit(const Json::Value& value,
    }



MEM_SWAP_LIMIT is computed as memLimit + MEM_SWAP_LIMIT_EXTRA_BYTES with unsigned arithmetic; if a caller supplies a large memLimit this can overflow and silently wrap, producing an invalid/too-small swap limit. Consider validating an upper bound (e.g., reject values where memLimit > UINT_MAX - MEM_SWAP_LIMIT_EXTRA_BYTES) and/or switching to a string/64-bit safe path when writing to the template dictionary.

Suggested change

// Prevent unsigned overflow when computing the swap limit

if (memLimit > (UINT_MAX - MEM_SWAP_LIMIT_EXTRA_BYTES))

{

AI_LOG_ERROR("memory limit too large, would overflow swap limit");

return false;

}

Copilot · 2026-03-09T20:53:10Z

bundle/lib/source/DobbySpecConfig.cpp

+
+static constexpr unsigned MEM_SWAP_LIMIT_EXTRA_BYTES = 200u * 1024u * 1024u;


MEM_SWAP_LIMIT_EXTRA_BYTES introduces a hard-coded 200MB policy with no rationale or configurability; this makes the runtime behavior difficult to tune across devices. Consider documenting why 200MB is required (and what it represents) or making it a configurable setting tied to platform defaults.

Suggested change

static constexpr unsigned MEM_SWAP_LIMIT_EXTRA_BYTES = 200u * 1024u * 1024u;

// Additional swap limit headroom (in bytes) added on top of MEM_LIMIT.

// The default of 200MB has historically been used as a conservative value

// to account for kernel overhead and transient memory spikes on typical

// target devices. If porting to hardware with significantly different

// memory characteristics, this value can be overridden at build time by

// defining MEM_SWAP_LIMIT_EXTRA_BYTES (for example via

// -DMEM_SWAP_LIMIT_EXTRA_BYTES=<bytes> in CXXFLAGS).

#ifndef MEM_SWAP_LIMIT_EXTRA_BYTES

static constexpr unsigned MEM_SWAP_LIMIT_EXTRA_BYTES = 200u * 1024u * 1024u;

#endif

Copilot · 2026-03-09T20:53:10Z

bundle/lib/source/templates/OciConfigJson1.0.2-dobby.template

+                "limit": {{MEM_LIMIT}},
+                "swap": {{MEM_SWAP_LIMIT}},
+                "swappiness": 60


This template sets swap greater than limit (MEM_SWAP_LIMIT is derived from MEM_LIMIT plus extra bytes). That means the container can exceed the memory limit by swapping, so it will not be OOM-killed at the point it reaches the memory limit (which conflicts with the PR title/description). If the goal is to trigger OOM at the configured memory limit when host swap is enabled, consider setting swap equal to the memory limit (cgroup v1 semantics) or otherwise aligning the swap value with the intended kill threshold.

Copilot · 2026-03-09T20:53:10Z

bundle/lib/source/templates/OciConfigJson1.0.2-dobby.template

+                "swap": {{MEM_SWAP_LIMIT}},
+                "swappiness": 60


"swappiness": 60 is a new, hard-coded behavioral change that will affect memory reclamation/swap behavior for all containers using this template. If this value is required for the OOM-kill fix, consider making it configurable (template placeholder) or omitting it to keep existing default behavior, and document the intended impact.

Suggested change

"swap": {{MEM_SWAP_LIMIT}},

"swappiness": 60

"swap": {{MEM_SWAP_LIMIT}}{{#MEM_SWAPPINESS_SECTION}},

"swappiness": {{MEM_SWAPPINESS}}{{/MEM_SWAPPINESS_SECTION}}

Copilot · 2026-03-09T20:53:11Z

bundle/lib/source/templates/OciConfigJsonVM1.0.2-dobby.template

+                "limit": {{MEM_LIMIT}},
+                "swap": {{MEM_SWAP_LIMIT}},
+                "swappiness": 60


This template sets swap greater than limit (MEM_SWAP_LIMIT is derived from MEM_LIMIT plus extra bytes). That means the container can exceed the memory limit by swapping, so it will not be OOM-killed at the point it reaches the memory limit (which conflicts with the PR title/description). If the goal is to trigger OOM at the configured memory limit when host swap is enabled, consider setting swap equal to the memory limit (cgroup v1 semantics) or otherwise aligning the swap value with the intended kill threshold.

Copilot · 2026-03-09T20:53:11Z

bundle/lib/source/templates/OciConfigJsonVM1.0.2-dobby.template

+                "swap": {{MEM_SWAP_LIMIT}},
+                "swappiness": 60


"swappiness": 60 is a new, hard-coded behavioral change that will affect memory reclamation/swap behavior for all containers using this template. If this value is required for the OOM-kill fix, consider making it configurable (template placeholder) or omitting it to keep existing default behavior, and document the intended impact.

Suggested change

"swap": {{MEM_SWAP_LIMIT}},

"swappiness": 60

"swap": {{MEM_SWAP_LIMIT}}{{#MEM_SWAPPINESS_ENABLED}},

"swappiness": {{MEM_SWAPPINESS}}{{/MEM_SWAPPINESS_ENABLED}}

RDKEMW-8825: App not killed when container reaches memory limit

db14302

Added "swap" limit in the OCI config templates to enable OOM killing when memory limit is reached when swap memory is enabled. Signed-off-by: Gurdal Oruklu <gurdal_oruklu@comcast.com>

Copilot AI review requested due to automatic review settings March 9, 2026 20:49

Copilot started reviewing on behalf of goruklu March 9, 2026 20:49 View session

Copilot AI reviewed Mar 9, 2026

View reviewed changes

goruklu changed the title ~~RDKEMW-8825: App not killed when container reaches memory limit~~ RDKEMW-15176: set swap memory limit for containers Mar 9, 2026

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RDKEMW-15176: set swap memory limit for containers#419

RDKEMW-15176: set swap memory limit for containers#419
goruklu wants to merge 1 commit intordkcentral:release/v3.14from
goruklu:RDKEMW-15176-8.3.4-swap-limit

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		@@ -1274,6 +1278,7 @@ bool DobbySpecConfig::processMemLimit(const Json::Value& value,
		}

+    // Prevent unsigned overflow when computing the swap limit
+    if (memLimit > (UINT_MAX - MEM_SWAP_LIMIT_EXTRA_BYTES))
+    {
+        AI_LOG_ERROR("memory limit too large, would overflow swap limit");
+        return false;
+    }


		static constexpr unsigned MEM_SWAP_LIMIT_EXTRA_BYTES = 200u * 1024u * 1024u;

-static constexpr unsigned MEM_SWAP_LIMIT_EXTRA_BYTES = 200u * 1024u * 1024u;
+// Additional swap limit headroom (in bytes) added on top of MEM_LIMIT.
+// The default of 200MB has historically been used as a conservative value
+// to account for kernel overhead and transient memory spikes on typical
+// target devices. If porting to hardware with significantly different
+// memory characteristics, this value can be overridden at build time by
+// defining MEM_SWAP_LIMIT_EXTRA_BYTES (for example via
+// -DMEM_SWAP_LIMIT_EXTRA_BYTES=<bytes> in CXXFLAGS).
+#ifndef MEM_SWAP_LIMIT_EXTRA_BYTES
+static constexpr unsigned MEM_SWAP_LIMIT_EXTRA_BYTES = 200u * 1024u * 1024u;
+#endif

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goruklu commented Mar 9, 2026

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