diff options
Diffstat (limited to 'Documentation/livepatch')
| -rw-r--r-- | Documentation/livepatch/livepatch.txt | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/Documentation/livepatch/livepatch.txt b/Documentation/livepatch/livepatch.txt index 9bcdef277a36..896ba8941702 100644 --- a/Documentation/livepatch/livepatch.txt +++ b/Documentation/livepatch/livepatch.txt @@ -183,6 +183,20 @@ tasks. No proper signal is actually delivered (there is no data in signal pending structures). Tasks are interrupted or woken up, and forced to change their patched state. +Administrator can also affect a transition through +/sys/kernel/livepatch/<patch>/force attribute. Writing 1 there clears +TIF_PATCH_PENDING flag of all tasks and thus forces the tasks to the patched +state. Important note! The force attribute is intended for cases when the +transition gets stuck for a long time because of a blocking task. Administrator +is expected to collect all necessary data (namely stack traces of such blocking +tasks) and request a clearance from a patch distributor to force the transition. +Unauthorized usage may cause harm to the system. It depends on the nature of the +patch, which functions are (un)patched, and which functions the blocking tasks +are sleeping in (/proc/<pid>/stack may help here). Removal (rmmod) of patch +modules is permanently disabled when the force feature is used. It cannot be +guaranteed there is no task sleeping in such module. It implies unbounded +reference count if a patch module is disabled and enabled in a loop. + 3.1 Adding consistency model support to new architectures --------------------------------------------------------- @@ -439,8 +453,8 @@ Information about the registered patches can be found under /sys/kernel/livepatch. The patches could be enabled and disabled by writing there. -/sys/kernel/livepatch/<patch>/signal attribute allows administrator to affect a -patching operation. +/sys/kernel/livepatch/<patch>/signal and /sys/kernel/livepatch/<patch>/force +attributes allow administrator to affect a patching operation. See Documentation/ABI/testing/sysfs-kernel-livepatch for more details. |