Messages in this thread | | | Date | Mon, 11 Sep 2017 13:10:30 +0200 | From | Christoph Hellwig <> | Subject | Re: [RFC PATCH v8 2/2] mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags |
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On Mon, Sep 11, 2017 at 11:47:14AM +0200, Jan Kara wrote: > On Fri 08-09-17 12:35:13, Dan Williams wrote: > > The mmap(2) syscall suffers from the ABI anti-pattern of not validating > > unknown flags. However, proposals like MAP_SYNC and MAP_DIRECT need a > > mechanism to define new behavior that is known to fail on older kernels > > without the support. Define a new MAP_SHARED_VALIDATE flag pattern that > > is guaranteed to fail on all legacy mmap implementations. > > > > With this in place new flags can be defined as: > > > > #define MAP_new (MAP_SHARED_VALIDATE | val) > > Is this changelog stale? Given MAP_SHARED_VALIDATE will be new mapping > type, I'd expect we define new flags just as any other mapping flags... > I see no reason why MAP_SHARED_VALIDATE should be or'ed to that.
Btw, I still think it should be a new hidden flag and not a new mapping type. I brought this up last time, so maybe I missed the answer to my concern.
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