Messages in this thread | | | Subject | Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK | From | Rik van Riel <> | Date | Tue, 08 Aug 2017 11:46:08 -0400 |
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On Tue, 2017-08-08 at 08:19 -0700, Mike Kravetz wrote:
> The other question I was trying to bring up is "What does > MADV_WIPEONFORK > mean for various types of mappings?" For example, if we allow > MADV_WIPEONFORK on a file backed mapping what does that mapping look > like in the child after fork? Does it have any connection at all to > the > file? Or, do we drop all references to the file and essentially > transform > it to a private (or shared?) anonymous mapping after fork. What > about > System V shared memory? What about hugetlb?
My current patch turns any file-backed VMA into an empty anonymous VMA if MADV_WIPEONFORK was used on that VMA.
> If the use case is fairly specific, then perhaps it makes sense to > make MADV_WIPEONFORK not applicable (EINVAL) for mappings where the > result is 'questionable'.
That would be a question for Florian and Colm.
If they are OK with MADV_WIPEONFORK only working on anonymous VMAs (no file mapping), that certainly could be implemented.
On the other hand, I am not sure that introducing cases where MADV_WIPEONFORK does not implement wipe-on-fork semantics would reduce user confusion...
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