On Wed, Jan 15, 2020 at 07:50:55AM +0100, Christoph Hellwig wrote:
On Tue, Jan 14, 2020 at 02:03:03PM -0500, Waiman Long wrote:
The commit 91d2a812dfb9 ("locking/rwsem: Make handoff writer optimistically spin on owner") will allow a recently woken up waiting writer to spin on the owner. Unfortunately, if the owner happens to be RWSEM_OWNER_UNKNOWN, the code will incorrectly spin on it leading to a kernel crash. This is fixed by passing the proper non-spinnable bits to rwsem_spin_on_owner() so that RWSEM_OWNER_UNKNOWN will be treated as a non-spinnable target.
Fixes: 91d2a812dfb9 ("locking/rwsem: Make handoff writer optimistically spin on owner")
Reported-by: Christoph Hellwig hch@lst.de Signed-off-by: Waiman Long longman@redhat.com
This survives all the tests that showed the problems with the original code:
Tested-by: Christoph Hellwig hch@lst.de
Thanks!