Re: [patch 6/7] process filtering for fault-injection capabilities

[Don Mullis <dwm@meer.net>]

On Thu, 2006-10-12 at 16:43 +0900, Akinobu Mita wrote:
> This patch provides process filtering feature.
> The process filter allows failing only permitted processes
> by /proc/<pid>/make-it-fail

Akinobu: Toward the end of the previous round of review, we had 
the following exchange:
        
        On Tue, 2006-09-19 at 17:05 +0800, Akinobu Mita wrote:
        On Mon, Sep 18, 2006 at 10:54:51PM -0700, Don Mullis wrote:
        > > Add functionality to the process_filter variable: A negative argument
        > > injects failures for only for pid==-process_filter, thereby permitting
        > > per-process failures from boot time.
        > > 
        > 
        > Is it better to add new filter for this purpose?
        > Because someone may want to filter by tgid instead of pid.
        > 
        > - positive value is for task->pid
        > - nevative value is for task->tgid
        
        Your idea sounds good to me.


So naturally I'm wondering why the functionality was dropped.
An application I had in mind was to identify which of the boot-time
calls to the slab allocator must not fail but are not yet marked
__GFP_NOFAIL (some experimentation showed that for pid 1 there are
lots of these).

Andrew: Would such an exercise would be worth the effort?