diff --git a/Documentation/criu.txt b/Documentation/criu.txt index 606935790..40ede84e2 100644 --- a/Documentation/criu.txt +++ b/Documentation/criu.txt @@ -465,6 +465,30 @@ The 'mode' may be one of the following: *skip*::: Don't lock the network. If *--tcp-close* is not used, the network must be locked externally to allow CRIU to dump TCP connections. +*--allow-uprobes*:: + Allow dumping when uprobes vma is present. When used on dump, this option is + required on restore as well. + + A uprobes vma is automatically created by the kernel once a uprobe is + triggered. This mapping is not removed even once the uprobe is deleted. So, + even if a process once had uprobes attached to it, and they're removed by + the time the process is dumped, this option is still required because criu + has no way of knowing whether there are active uprobes or not. + + When using this option on restore, make sure the uprobes (if any) active on + the dumped processes are still active. Otherwise, when execution reaches + a uprobe'd location in any of the restored processes, that process will be + sent a SIGTRAP. + + As an example, say a uprobe is set at function foo in the executable of the + process p_bar. Whenever execution in p_bar reaches function foo, the uprobe + is triggered. If the uprobe has been triggered at least once, then the kernel + will have created the uprobes vma. To dump p_bar, this option is + necessary. After dumping, say the uprobe is deleted. Now, on restoring with + this option, once execution reaches function foo, SIGTRAP will be sent to + the restored p_bar. Unless it has a signal handler installed for SIGTRAP, + it will be terminated and core dumped. + *restore* ~~~~~~~~~ Restores previously checkpointed processes. @@ -692,6 +716,10 @@ The 'mode' may be one of the following: *--skip-file-rwx-check*:: Skip checking file permissions (r/w/x for u/g/o) on restore. +*--allow-uprobes*:: + Required when dumped with this option. Refer to this option in the section + on dumping for more details. + *check* ~~~~~~~ Checks whether the kernel supports the features needed by *criu* to