On Mon, Jun 03, 2019 at 11:24:49AM +0200, Alexander Potapenko wrote: > On Sat, Jun 1, 2019 at 3:18 AM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > On Wed, 29 May 2019 14:38:11 +0200 Alexander Potapenko <glider@xxxxxxxxxx> wrote: > > > > > Print the currently enabled stack and heap initialization modes. > > > > > > The possible options for stack are: > > > - "all" for CONFIG_INIT_STACK_ALL; > > > - "byref_all" for CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL; > > > - "byref" for CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF; > > > - "__user" for CONFIG_GCC_PLUGIN_STRUCTLEAK_USER; > > > - "off" otherwise. > > > > > > Depending on the values of init_on_alloc and init_on_free boottime > > > options we also report "heap alloc" and "heap free" as "on"/"off". > > > > Why? > > > > Please fully describe the benefit to users so that others can judge the > > desirability of the patch. And so they can review it effectively, etc. > I'm going to update the description with the following passage: > > Print the currently enabled stack and heap initialization modes. > > Stack initialization is enabled by a config flag, while heap > initialization is configured at boot time with defaults being set > in the config. It's more convenient for the user to have all information > about these hardening measures in one place. > > Does this make sense? > > Always! > > > > > In the init_on_free mode initializing pages at boot time may take some > > > time, so print a notice about that as well. > > > > How much time? > I've seen pauses up to 1 second, not actually sure they're worth a > separate line in the log. > Kees, how long were the delays in your case? I didn't measure it, but I think it was something like 0.5 second per GB. I noticed because normally boot flashes by. With init_on_free it pauses for no apparent reason, which is why I suggested the note. (I mean *I* knew why it was pausing, but it might surprise someone who sets init_on_free=1 without really thinking about what's about to happen at boot.) -- Kees Cook
