Hi Andrew, On Mon, Jun 30, 2014 at 06:57:48PM +0000, Lewycky, Andrew wrote: > As an aside we found another small issue: amd_iommu_bind_pasid calls > get_task_mm. This bumps the mm_struct use count and it will never be > released. This would prevent the buggy code path described above from > ever running in the first place. You are right, the current code is a bit problematic, but to fix this no new notifier chain in mm-code is needed. In fact, using get_task_mm() is a good way to keep a reference to the mm as a user (an external device is in fact another user) and defer the destruction of the mappings to the file-close path (where you can call mmput to destroy it). So this is another way to solve the problem without any new notifier. Joerg -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>