https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=297335
Mark Johnston <[email protected]> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|New |Open --- Comment #1 from Mark Johnston <[email protected]> --- > An NMI cannot interrupt itself — further NMIs are blocked until IRET This is a problem in itself. dtrace fbt probes install breakpoints in kernel text; once the dtrace probe fires and the handler runs, we return to the original context via iret. If that happens in the context of an NMI handler, then dtrace will silently re-enable NMIs while the NMI handler continues executing. The amd64 NMI handler is not re-entrant, so if a second NMI is raised before the handler finishes, then we will crash. For the original problem, probably it's sufficient to ensure that dtrace_probe() simply returns early if it detects it's in an NMI handler? And it should increment an error counter so that the user can see that it's dropping events. -- You are receiving this mail because: You are the assignee for the bug.
