Re: [PATCH V3] mm: Allow userland to request that the kernel clear memory on release

[Matthew Garrett]

On Fri, Apr 26, 2019 at 12:45 AM Vlastimil Babka <vbabka@xxxxxxx> wrote:
>
> On 4/26/19 12:58 AM, Matthew Garrett wrote:
> > Updated based on feedback from Jann - for now let's just prevent setting
> > the flag on anything that has already mapped some pages, which avoids
> > child processes being able to interfere with the parent. In addition,
>
> That makes the API quite tricky and different from existing madvise()
> modes that don't care. One would for example have to call
> madvise(MADV_WIPEONRELEASE) before mlock(), otherwise mlock() would
> fault the pages in (unless MLOCK_ONFAULT). As such it really looks like
> a mmap() flag, but that's less flexible.
>
> How bout just doing the CoW on any such pre-existing pages as part of
> the madvise(MADV_WIPEONRELEASE) call?

I'll look into the easiest way to do that.