a4e63bce14
Registration of a mmu_notifier requires the caller to hold a mmget() on the mm as registration is not permitted to race with exit_mmap(). There is a BUG_ON inside the mmu_notifier to guard against this. Normally creating a umem is done against current which implicitly holds the mmget(), however an implicit ODP child is created from a pagefault work queue and is not guaranteed to have a mmget(). Call mmget() around this registration and abort faulting if the MM has gone to exit_mmap(). Before the patch below the notifier was registered when the implicit ODP parent was created, so there was no chance to register a notifier outside of current. Fixes: c571feca2dc9 ("RDMA/odp: use mmu_notifier_get/put for 'struct ib_ucontext_per_mm'") Link: https://lore.kernel.org/r/20200227114118.94736-1-leon@kernel.org 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.
Description
Languages
C
97.6%
Assembly
1%
Shell
0.5%
Python
0.3%
Makefile
0.3%