On 24.01.23 06:42, Alistair Popple wrote:
Kernel drivers that pin pages should account these pages against either user->locked_vm or mm->pinned_vm and fail the pinning if RLIMIT_MEMLOCK is exceeded and CAP_IPC_LOCK isn't held. Currently drivers open-code this accounting and use various methods to update the atomic variables and check against the limits leading to various bugs and inconsistencies. To fix this introduce a standard interface for charging pinned and locked memory. As this involves taking references on kernel objects such as mm_struct or user_struct we introduce a new vm_account struct to hold these references. Several helper functions are then introduced to grab references and check limits. As the way these limits are charged and enforced is visible to userspace we need to be careful not to break existing applications by charging to different counters. As a result the vm_account functions support accounting to different counters as required. A future change will extend this to also account against a cgroup for pinned pages.
The term "vm_account" is misleading, no? VM_ACCOUNT is for accounting towards the commit limit ....
-- Thanks, David / dhildenb
