On Fri, Nov 09, 2018 at 12:36:34PM -0800, Andrew Morton wrote: > On Wed, 7 Nov 2018 20:15:36 -0800 "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx> wrote: > > > Android uses ashmem for sharing memory regions. We are looking forward > > to migrating all usecases of ashmem to memfd so that we can possibly > > remove the ashmem driver in the future from staging while also > > benefiting from using memfd and contributing to it. Note staging drivers > > are also not ABI and generally can be removed at anytime. > > > > One of the main usecases Android has is the ability to create a region > > and mmap it as writeable, then add protection against making any > > "future" writes while keeping the existing already mmap'ed > > writeable-region active. This allows us to implement a usecase where > > receivers of the shared memory buffer can get a read-only view, while > > the sender continues to write to the buffer. > > See CursorWindow documentation in Android for more details: > > https://developer.android.com/reference/android/database/CursorWindow > > It appears that the memfd_create and fcntl manpages will require > updating. Please attend to this at the appropriate time? Yes, I am planning to send those out shortly. I finished working on them. Also just to let you know, I posted a fix for the security issue Jann Horn reported and requested him to test it: https://lore.kernel.org/lkml/20181109234636.GA136491@xxxxxxxxxx/T/#m8d9d185e6480d095f0ab8f84bcb103892181f77d This fix along with the 2 other patches I posted in v3 are all that's needed. thanks! - Joel
