67f269b37f
When this code was consolidated the intention was that the VMA would become backed by anonymous zero pages after the zap_vma_pte - however this very subtly relied on setting the vm_ops = NULL and clearing the VM_SHARED bits to transform the VMA into an anonymous VMA. Since the vm_ops was removed this broke. Now userspace gets a SIGBUS if it touches the vma after disassociation. Instead of converting the VMA to anonymous provide a fault handler that puts a zero'd page into the VMA when user-space touches it after disassociation. Cc: stable@vger.kernel.org Suggested-by: Andrea Arcangeli <aarcange@redhat.com> Fixes: 5f9794dc94f5 ("RDMA/ucontext: Add a core API for mmaping driver IO memory") Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.