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Subject[PATCH v0 3/3] livepatch: update documentation for shadow variables
Update livepatch shadow variable documentation with respect to new
atomic replace / cumulative patch functionality.

Signed-off-by: Joe Lawrence <>
Documentation/livepatch/shadow-vars.txt | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/Documentation/livepatch/shadow-vars.txt b/Documentation/livepatch/shadow-vars.txt
index 89c66634d600..9a2754cf551c 100644
--- a/Documentation/livepatch/shadow-vars.txt
+++ b/Documentation/livepatch/shadow-vars.txt
@@ -179,6 +179,30 @@ doesn't matter what data value the shadow variable holds, its existence
suggests how to handle the parent object.

+Use in cumulative patches
+Cumulative livepatches provide a "one-stop" module containing all active
+livepatch code. A cumulative patch disables and replaces any previously
+loaded livepatch. Shadow variable lifetimes should be carefully
+considered when loading cumulative livepatches:
+- If shadow variables lifetimes are specific to livepatch module
+ versions, it may make sense to free them when the corresponding
+ livepatch module is unloaded.
+- If shadow variable instances may be safely handled across cumulative
+ livepatch module versions, then it may make sense to free them from
+ unpatch callbacks. When a cumulative patch replaces an existing
+ livepatch, only the cumulative patch's callbacks will be executed.
+ This means that new cumulative livepatches may be loaded while
+ deprecated / disabled livepatches may be unloaded without clearing
+ existing shadow variables.
+See Documentation/livepatch/callbacks.txt and cumulative.txt for more
+information on these subjects.
3. References

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