Re: [patch 2/3] mm: memory: remove ->vm_file check on shared writable vmas

From: Johannes Weiner
Date: Tue Dec 02 2014 - 10:18:41 EST

On Tue, Dec 02, 2014 at 09:58:25AM +0100, Jan Kara wrote:
> On Mon 01-12-14 17:58:01, Johannes Weiner wrote:
> > The only way a VMA can have shared and writable semantics is with a
> > backing file.
> OK, one always learns :) After some digging I found that MAP_SHARED |
> MAP_ANONYMOUS mappings are in fact mappings of a temporary file in tmpfs.
> It would be worth to mention this in the changelog I believe. Otherwise
> feel free to add:
> Reviewed-by: Jan Kara <jack@xxxxxxx>

Thanks, Jan. I updated the changelog to read:

Shared anonymous mmaps are implemented with shmem files, so all VMAs
with shared writable semantics also have an underlying backing file.
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