[PATCH v5 2/3] mm: init: report memory auto-initialization features at boot time

[Alexander Potapenko]

On Sat, Jun 1, 2019 at 3:18 AM Andrew Morton <akpm at linux-foundation.org> wrote:
>
> On Wed, 29 May 2019 14:38:11 +0200 Alexander Potapenko <glider at google.com> 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?



-- 
Alexander Potapenko
Software Engineer

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